STAR

, Stella, in Astronomy, a general name for all the heavenly bodies.

The Stars are distinguished, from the phenomena, &c, into sived and erratic or wandering.

Erratic or Wandering Stars, are those which are continually changing their places and distances, with regard to each other. These are what are properly called planets. Though to the same class may likewise be referred comets or blazing Stars.

Fixed Stars, called also barely Stars, by way of eminence, are those which have usually been observed to keep the same distance, with regard to each other.

The chief circumstances observable in the fixed Stars, are their distance, magnitude, number, nature, and motion. Of each of which in their order.

Distance of the Fixed Stars. The fixed Stars are so extremely remote from us, that we have no distances in the planetary system to compare to them. Their immense distance appears from hence, that they have no sensible parallax; that is, that the diameter of the earth's annual orbit, which is nearly 190 millions of miles, bears no sensible proportion to their distance.

Mr. Huygens (Cosmotheor. lib. 4) attempts to determine the distance of the Stars, by making the aperture of a telescope so small, as that the sun through it appears no larger than Sirius; which he found to be only as 1 to 27664 of his diameter, when seen with the naked eye. So that, were the sun's distance 27664 times as much as it is, it would then be seen of the same diameter with Sirius. And hence, supposing Sirius to be a sun of the same magnitude with our sun, the distance of Sirius will be found to be 27664 times the distance of the sun, or 345 million times the earth's diameter.

Dr. David Gregory investigated the distance of Sirius, by supposing it of the same magnitude with the sun, and of the same apparent diameter with Jupiter in opposition: as may be seen at large in his Astronomy, lib. 3, prop. 47.

Cassini (Mem. Acad. 1717), by comparing Jupiter and Sirius, when viewed through the same telescope, inferred, that the diameter of that planet was 10 times as great as that of the Star; and the diameter of Jupiter being 50″, he concluded that the diameter of Sirius was about 5″; supposing then that the real magnitude of Sirius is equal to that of the sun, and the distance of the sun from us 12000 diameters of the earth, and the apparent diameter of Sirius being to that of the sun as 1 to 384, the distance of Sirius becomes equal to 4608000 diameters of the earth.

These methods of Huygens, Gregory, and Cassini, are conjectural and precarious; both because the sun and Sirius are supposed of equal magnitude, and also because it is supposed the diameter of Sirius is determined with sufficient exactness.

Mr. Michell has proposed an enquiry into the probable parallax and magnitude of the fixed Stars, from the quantity of light which they afford us, and the peculiar circumstances of their situation. With this view he supposes, that they are, on a medium, equal in magnitude and natural brightness to the sun; and then proceeds to inquire, what would be the parallax of the sun, if he were to be removed so far from us, as to make the quantity of the light, which we should then receive from him, no more than equal to that of the sixed Stars. Accordingly, he assumes Saturn in opposition, as equal, or nearly equal in light to the brightest fixed Star. As the mean distance of Saturn from the sun is equal to about 2082 of the sun's semidiameters, the density of the sun's light at Saturn will consequently be less than at his own surface, in the ratio of the square of 2082 or 4334724 to 1: If Saturn therefore reflected all the light that falls upon him, he would be less luminous in that same proportion. And besides, his apparent diameter, in the opposition, being but about the 105th part of that of the sun, the quantity of light which we receive from him must be again diminished in the ratio of the square of 105 or 11025 to 1. Consequently, by multiplying these two numbers together, we shall have the whole of the light of the sun to that of Saturn, as the square nearly of 220,000 or 48,400,000,000 to 1. Hence, removing the sun to 220,000 times his present distance, he would still appear at least as bright as Saturn, and his whole parallax upon the diameter of the earth's orbit would be less than 2 seconds: and this must be assumed for the parallax of the brightest of the fixed Stars, upon the supposition that their light does not exceed that of Saturn.

By a like computation it may be found, that the distance, at which the sun would afford us as much light as we receive from Jupiter, is not less than 46,000 times his present distance, and his whole parallax in that case, upon the diameter of the earth's orbit, would not be more than 9 seconds; the light of Jupiter and Saturn, as seen from the earth, being in the ratio of about 22 to 1, when they are both in opposition, and supposing them to reflect equally in proportion to the whole of the light that falls upon them. But if Jupiter and Saturn, instead of reflecting the whole of the light that falls upon them, should really reflect only a part of it, as a 4th, or a 6th, which may be the case, the above distances must be increased in the ratio of 2 or 2 1/2 to 1, to make the sun's light no more than equal to theirs; and his parallax would be less in the same proportion. Supposing then that the fixed Stars are of the same magnitude and brightness with the sun, it is no wonder that their parallax should hitherto have escaped observation; since in this case it could hardly amount to 2 seconds, and probably not more than one in Sirius himself, though he had been placed in the pole of the ecliptic; and in those that appear much less luminous, as g Draconis, which is only of the 3d magnitude, it could hardly be expected to be sensible with such instruments as have hitherto been used. However, Mr. Mi- | chell suggests, that it is not impracticable to construct instruments capable of distinguishing even to the 20th part of a second, provided the air will admit of that degree of exactness. This ingenious writer apprehends that the quantity of light which we receive from Sirius, does not exceed the light we receive from the least fixed Star of the 6th magnitude, in a greater ratio than that of 1000 to 1, nor less than that of 400 to 1; and the smaller Stars of the 2d magnitude seem to be about a mean proportional between the other two. Hence the whole parallax of the least sixed Stars of the 6th magnitude, supposing them of the same size and native brightness with the sun, should be from about 2‴ to 3‴, and their distance from about 8 to 12 million times that of the sun: and the parallax of the smaller Stars of the 2d magnitude, upon the same supposition, should be about 12‴, and their distance about 2 million times that of the sun.

This author farther suggests, that, from the apparent situation of the Stars in the heavens, there is the greatest probability that the Stars are collected together in clusters in some places, where they form a kind of systems, whilst in others there are either few or none of them; whether this disposition be owing to their mutual gravitation, or to some other law or appointment of the Creator. Hence it may be inferred, that such double Stars, &c. as appear to consist of two or more Stars placed very near together, do really consist of Stars placed near together, and under the influence of some general law: and he proceeds to inquire whether, if the Stars be collected into systems, the sun does not likewise make one of some system, and which fixed Stars those are that belong to the same system with him.

Those Stars, he apprehends, which are found in clusters, and surrounded by many others at a small distance from them, belong probably to other systems, and not to ours. And those Stars, which are surrounded with nebulæ, are probably only very large Stars which, on account of their superior magnitude, are singly visible, while the others, which compose the remaining parts of the same system, are so small as to escape our sight. And those nebulæ in which we can discover either none or only a few Stars, even with the assistance of the best telescopes, are probably systems that are still more distant than the rest. For other particulars of this inquiry, see Philos. Trans. vol. 57, pa. 234 &c.

As the distance of the fixed Stars is best determined by their parallax, various methods have been pursued, though hitherto without success, for investigating it; the result of the most accurate observations having given us little more than a distant approximation; from which however we may conclude, that the nearest of the fixed Stars cannot be less than 40 thousand diameters of the whole annual orbit of the earth distant from us.

The method pointed out by Galileo, and attempted by Hook, Flamsteed, Molyneux, and Bradley, of taking the distances of such Stars from the zenith as pass very near it, has given us a much juster idea of the immense distance of the Stars, and furnished an approximation to their parallax, much nearer the truth, than any we had before.

Dr. Bradley assures us (Philos. Trans. num. 406, or Abr. vol. 6, pa. 162), that had the parallax amounted to a single second, or two at most, he should have perceived it in the great number of observations which he made, especially upon g Draconis; and that it seemed to him very probable, that the annual parallax of this Star does not amount to a single second, and consequently that it is above 400 thousand times farther from us than the sun.

But Dr. Herschel, to whose industry and ingenuity, in exploring the heavens, astronomy is already much indebted, remarks, that the instrument used on this occasion, being the same with the present zenith sectors, can hardly be allowed capable of shewing an angle of one or even two seconds, with accuracy: and besides, the Star on which the observations were made, is only a bright Star of the 3d magnitude, or a small Star of the 2d; and that therefore its parallax is probably much less than that of a Star of the first magnitude. So that we are not warrauted in inferring, that the parallax of the Stars in general does not exceed 1″, whereas those of the first magnitude may have, notwithstanding the result of Dr. Bradley's observations, a parallax of several seconds.

As to the method of zenith distances, it is liable to considerable errors, on account of refraction, the change of position of the earth's axis, arising from nutation, precession of the equinoxes, or other causes, and the aberration of light.

Dr. Herschel has proposed another method, by means of double Stars, which is free from these errors, and of such a nature, that the annual parallax, even if it should not exceed the 10th part of a second, may still become visible, and be ascertained at least much nearer than heretofore. This method, which was first proposed in an imperfect manner by Galileo, and has been also mentioned by other authors, is capable of every improvement which the telescope and mechanism of micrometers can furnish. To give a general idea of it, let O and E be two opposite points of the annual orbit, taken in the same plane with two stars A, B, of unequal magnitudes. Let the angle AOB be observed when the earth is at O, and AEB be observed when the earth is at E. From the difference of these angles, when there is any, the parallax of the Stars may be computed, according to the theory subjoined. These two Stars ought to be as near as possible to each other, and also to differ as much in magnitude as we can find them.

This theory of the annual parallax of double Stars, with the method of computing from thence what is usually called the parallax of the fixed Stars, or of single Stars of the first magnitude, such as are nearest to us, supposes 1st, that the Stars are all about the size of the sun; and 2dly, that the difference in their apparent magnitudes, is owing to their different distances, so as that a Star of the 2d, 3d, or 4th magnitude, is 2, 3, or 4 times as far off as one of the first. These principles, which Dr. Herschel premises as po<*>lata, have so great a probability in their favour, that they will | scarcely be objected to by those who are in the least acquainted with the doctrine of chances. See Mr. Michell's Inquiry, &c. already cited. And Philos. Trans. vol. 57, pa. 234 . . . . 240. Also Dr. Halley, on the Number, Order, and Light of the fixed Stars, in the Philos. Trans. vol. 31, or Abr. vol. 6, pa. 148.

Therefore, let EO be the whole diameter of the earth's annual orbit; and let A, B, C be three Stars situated in the ecliptic, in such a manner, that they may appear all in one line OABC when the earth is at O. Now if OA, AB, BC be equal to each other, A will be a Star of the first magnitude, B of the second, and C of the third. Let us next suppose the angle OAE, or parallax of the whole orbit of the earth, to be 1″ of a degree; then, because very small angles, having the same subtense EO, may be taken to be in the inverse ratio of the lines OA, OB, OC, &c, we shall have EBO = 1/2″, and ECO = 1/3″, &c, also because EA = AB nearly, the angle AEB = ABE = 1/2″; and because BC = 1/2 BO = 1/2 BE nearly, the angle BEC = 1/2 BCE = 1/6″, and hence AEC = 1/2 + 1/6 = 2/3″; from all which it follows that, when the earth is at E, the Stars A and B appear at 1/2″ distant from one another, the Stars A and C at 2/3″ distant, and the Stars B and C only 1/6″ distant. In like man<*> may be deduced a general expression for the parallax that will become visible in the change of distance between the two Stars, by the removal of the earth from one extreme of her orbit to the other. Let P denote the total parallax of a fixed Star of the magnitude of the M order, and m the number of the order of a smaller Star, p denoting the partial parallax to be observed by the change in the distance of a double Star; then is , which gives P, when p is found by observation.

For Ex. Suppose a Star of the 1st magnitude should have a small Star of the 12th magnitude near it; then will the partial parallax we are to expect to see be , or 11/12 of the total parallax of the larger Star; and if we should, by observation, find the partial parallax between two such Stars to amount to 1″, then will the total parallax . Again, if the Stars be of the 3d and 24th magnitude, the total parallax will be ; so that if by observation p be found to be 1/10 of a second, the whole parallax P will come out .

Farther, the Stars being still in the ecliptic, suppose they should appear in one line, when the earth is in some other part of her orbit between E and O; then will the parallax be still expressed by the same algebraic formula, and one of the maxima will still lie at E, the other at O; but the whole effect will be divided into two parts, which will be in proportion to each other, as radius — sine to radius + sine of the Star's distance from the nearest conjunction or opposition.

When the Stars are any where out of the ecliptic, situated so as to appear in one line OABC perpendicular to EO, the maximum of parallax will still be expressed by ((m - M)/(mM))P; but there will arise another additional parallax in the conjunction and opposition, which will be to that which is found 90° before or after the sun, as the sine (s) of the latitude of the Stars seen at O, is to radius (1); and the effect of this parallax will be divided into two parts; half of it lying on one side of the large Star, the other half on the other side of it. This latter parallax will also be compounded with the former, so that the distance of the Stars in the conjunction and opposition will then be represented by the diagonal of a parallelogram, whose sides are the two semiparallaxes; a general expression for which will be .

When the Stars are in the pole of the ecliptic, s will be = 1, and the last formula becomes .

Again, let the Stars be at some distance, as 5″, from each other, and let them be both in the ecliptic. This case is resolvable into the first; for imagine the Star A to stand at I; then the angle AEI may be accounted equal to AOI; and as the foregoing formula, , gives us the angles AEB, AEC, we are to add AEI or 5″ to AEB, which will give IEB. In general, let the distance of the Stars be d, and let the observed distance at E be D; then will , and therefore the whole parallax of the annual orbit will be expressed by .

Suppose now the Stars to differ only in latitude, one being in the ecliptic, the other at some distance as 5″ north, when seen at O. This case may also be resolved by the former; for imagine the Stars B and C to be elevated at right angles above the plane of the figure, so that AOB, or AOC, may make an angle of 5″ at O; then instead of the lines OABC, EA, EB, EC, imagine them all to be planes at right angles to the figure; and it will appear that the parallax of the Stars in longitude, must be the same as if the small Star had been without latitude. And since the Stars B, C, by the motion of the earth from O to E, will not change their latitude, we shall have the following construction for finding the distance of the Stars AB and AC at E, and from thence the parallax P. | Let the triangle abb represent the situation of the Stars; ab is the subtense of 5″, the angle under which they are supposed to be seen at O. The quantity bb by the former theorem is found = ((m-M)/(mM))P, which is the partial parallax, that would have been seen by the earth's moving from O to E, if both Stars had been in the ecliptic; but, on account of the difference in latitude, it will now be represented by ab, the hypotenuse of the triangle abb: therefore in general, putting ab = d, ab = D, we have . Hence, D being found by observation, and the three d, m, M given, the total parallax is obtained.

When the Stars differ in longitude as well as latitude, this case may be resolved in the following manner. Let the triangle abb represent the situation of the Stars, ab = d being their distance seen at O, ab = D their distance seen at E. That the change bb, which is produced by the earth's motion, will be truly expressed by ((m - M)/(mM))P, may be proved as before, by supposing the Star a to have been placed at a. Now let the angle of position baa be taken by a micrometer, or by any other method sufficiently exact; then, by resolving the triangle aba, we obtain the longitudinal and latitudinal differences aa and ba of the two stars. Put aa = x, ba = y, and it will be x + bb = aq, whence .

If neither of the Stars should be in the ecliptic, nor have the same longitude or latitude, the last theorem will still serve to calculate the total parallax, whose maximum will lie in E. There will also arise another parallax, whose maximum will be in the conjunction and opposition, which will be divided, and lie on different sides of the large Star; but as the whole parallax is extremely small, it is not necessary to investigate every particular case of this kind; for by reason of the division of the parallax, which renders observations taken at any other time, except where it is greatest, very unfavourable, the formulæ would be of little use.

Dr. Herschel closes his account of this theory, with a general observation on the time and place where the maxima of parallax will happen. Thus, when two unequal Stars are both in the ecliptic, or, not being in the ecliptic, have equal latitudes, north or fouth, and the larger Star has most longitude, the maximum of the apparent distance will be when the sun's longitude is 90° more than the Star's, or when observed in the morning: and the minimum, when the longitude of the sun is 90° less than that of the Star, or when observed in the evening. But when the small Star has most longitude, the maximum and minimum, as well as the time of observation, will be the reverse of the former. And when the Stars differ in latitude, this makes no alteration in the place of the maximum or minimum, nor in the time of observation; that is, it is immaterial which of the two Stars has the greater latitude. Philos. Trans. vol. 72, art. 11.

The distance of the Star g Draconis appears, by Bradley's observations, already recited, to be at least 400,000 times that of the sun, and the distance of the nearest fixed Star, not less than 40,000 diameters of the earth's annual orbit: that is, the distance from the earth, of the former at least 38,000,000,000,000 miles, and the latter not less than 7,600,000,000,000 miles. As these distances are immensely great, it may both be amusing, and help to a clearer and more familiar idea, to compare them with the velocity of some moving body, by which they may be measured.

The swiftest motion we know of, is that of light, which passes from the sun to the earth in about 8 minutes; and yet this would be above 6 years traversing the first space, and near a year and a quarter in passing from the nearest fixed Star to the earth. But a cannon ball, moving on a medium at the rate of about 20 miles in a minute, would be 3 million 8 hundred thousand years in passing from g Draconis to the earth, and 760 thousand years passing from the nearest fixed Star. Sound, which moves at the rate of about 13 miles in a minute, would be 5 million 600 thousand years traversing the former distance, and 1 million 128 thousand, in passing through the latter.

The celebrated Huygens pursued speculations of this kind so far, as to believe it not impossible, that there may be Stars at such inconceivable distances, that their light has not yet reached the earth since its creation.

Dr. Halley has also advanced, what he says seems to be a metaphysical paradox (Philos. Trans. number 364, or Abr. vol. 6, pa. 148), viz, that the number of fixed Stars must be more than finite, and some of them more than at a finite distance from others: and Addison has justly observed, that this thought is far from being extravagant, when we consider that the universe is the work of infinite power, prompted by infinite goodness, and having an infinite space to exert itself in; so that our imagination can set no bounds to it.

Magnitude of the fixed Stars. The magnitudes of the Stars appear to be very different from one another; which difference may probably arise, partly from a diversity in their real magnitude, but principally from their distances, which are different.

To the bare eye, the Stars appear of some sensible magnitude, owing to the glare of light arising from the numberless reflections from the aërial particles &c about the eye: this makes us imagine the Stars to be much larger than they would appear, if we saw them only by the few rays which come directly from them, so as to enter our eyes without being intermixed with others.

Any person may be sensible of this, by looking at a Star of the first magnitude through a long narrow tube; which, though it takes in as much of the sky as would hold a thousand such stars, scarce renders that one visible. |

The Stars, on account of their apparently various sizes, have been distributed into several classes, called magnitudes. The 1st class, or Stars of the first magnitude, are those that appear largest, and may probably be nearest to us. Next to these, are those of the 2d magnitude; and so on to the 6th, which comprehends the smallest Stars visible to the naked eye. All beyond these, that can be perceived by the help of telescopes, are called telescopic stars. Not that all the Stars of each class appear justly of the same magnitude; there being great latitude in this respect; and those of the first magnitude appearing almost all different in lustre and size. There are also other Stars, of intermediate magnitudes, which astronomers cannot refer to one class rather than another, and therefore they place them between the two. Procyon, for instance, which Ptolomy makes of the first magnitude, and Tycho of the 2d, Flamsteed lays down as between the 1st and 2d. So that, instead of 6 magnitudes, we may say there are almost as many orders of Stars, as there are Stars; so great variations being observable in the magnitude, colour, and brightness of them.

There seems to be little chance of discovering with certainty the real size of any of the fixed Stars; we must therefore be content with an approximation, deduced from their parallax, if this should ever be found; and the quantity of light they afford us, compared with that of the sun. And to this purpose, Dr. Herschel informs us, that with a magnifying power of 6450, and by means of his new micrometer, he found the apparent diameter of a Lyræ to be 0″.355.

The Stars are also distinguished, with regard to their situation, into asterisms, or constellations; which are nothing but assemblages of several neighbouring Stars, considered as constituting some determinate figure, as os an animal, &c, from which it is therefore denominated: a division as ancient as the book of Job, in which mention is made of Orion, the Pleiades, &c.

Besides the Stars thus distinguished into magnitudes and constellations, there are others not reduced to either. Those not reduced into constellations, are called informes, or unformed Stars; of which kind several, so left at large by the ancients, have since been formed into new constellations by the modern astronomers, and especially by Hevelius.

Those not reduced to classes or magnitudes, are called nebulous Stars; but such as only appear faintly in clusters, in form of little lucid spots, nebulæ, or clouds.

Ptolomy sets down five of such nebulæ, viz, one at the extremity of the right hand of Perseus, which appears through the telescope, thick set with Stars; one in the middle of the crab, called Præsepe, or the Manger, in which Galileo counted above 40 Stars; one unformed near the sting of the Scorpion; another in the eye of Sagittarius, in which two Stars may be seen in a clear sky with the naked eye, and several more with the telescope; and the fisth in the head of Orion, in which Galileo counted 21 Stars.

Flamsteed observed a cloudy Star before the bow of Sagittarius, which consists of a great number of small Stars; and the Star d above the right shoulder of this constellation is encompassed with several more. Flamsteed and Cassini also discovered one between the great and little dog, which is very full of Stars, that are visible only by the telescope.

But the most remarkable of all the cloudy Stars, is that in the middle of Orion's sword, in which Huygens and Dr. Long observed 12 Stars, 7 of which (3 of them, now known to be 4, being very close together) seem to shine through a cloud, very lucid near the middle, but faint and ill defined about the edges. But the greatest discoveries of nebulæ and clusters of Stars, we owe to the powerful telescopes of Dr. Herschel, who has given accounts of some thousands of such nebulæ, in many of which the Stars seem to be innumerable, like grains of sand. See Philos. Trans. 1784, 1785, 1786, 1789. See Galaxy, and Magellanic clouds, and lucid Spots.

Cassini is of opinion, that the brightness of these proceeds from Stars so minute, as not to be distinguished by the best glasses: and this opinion is fully confirmed by the observations of Dr. Herschel, whose powerful telescopes shew those lucid specks to be composed entirely of masses of small Stars, like heaps of sand.

There are also many Stars which, though they appear single to the naked eye, are yet discovered by the telescope to be double, triple, &c. Of these, several have been observed by Cassini, Hooke, Long, Maskelyne, Hornsby, Pigott, Mayer, &c; but Dr. Herschel has been much the most successful in observations of this kind; and his success has been chiefly owing to the very extraordinary magnifying powers of the Newtonian 7 feet reflector which he has used, and the advantage of an excellent micrometer of his own construction. The powers which he has used, have been 146, 227, 278, 460, 754, 932, 1159, 1536, 2010, 3168, and even 6450. He has already formed a catalogue, containing 269 double Stars, 227 of which, as far as he knows, have not been noticed by any other person. Among these there are also some Stars that are treble, double-double, quadruple, double-treble, and multiple. His catalogue comprehends the names of the Stars, and the number in Flamsteed's catalogue, or such a description of those that are not contained in it, as will be found sufficient to distinguish them; also the comparative size of the Stars; their colours as they appeared to his view; their distances determined in several different ways; their angle of position with regard to the parallel of declination; and the dates when he first perceived the Stars to be double, treble, &c. His observations appear to commence with the year 1776, but almost all of them were made in the years 1779, 1780, 1781.

Dr. Herschel has distributed the double Stars contained in his catalogue, into 6 different classes. In the first he has placed all those which require a very superior telescope, with the utmost clearness of air, and every other favourable circumstance, to be seen at all, or well enough to judge of them; and there are 24 of these. To the 2d class belong all those double Stars that are proper for estimations by the eye, and very delicate measures by the micrometer; the number being 38. The 3d class comprehends all those double Stars, that are between 5″ and 15″ asunder; the number of them being 46. The 4th, 5th, and 6th classes contain | double Stars that are from 15″ to 30″, and from 30″ to 1′, and from 1′ to 2′ or more asunder; of which there are 44 in the 4th class, 51 in the 5th class, and 66 in the 6th class: the last of this class is a Tauri, number 87 of Flamsteed, whose apparent diameter, upon the meridian measured with a power of 460 at a mean of two observations 1″ 46‴, and with a power of 932 at a mean of two observations 1″ 12‴. See the list at large, Philosoph. Trans. vol. 72, art. 12.

The Stars are also distinguished, in each constellation, by numbers, or by the letters of the alphabet. This sort of distinction was introduced by John Bayer, in his Uranometria, 1654; where he denotes the Stars, in each constellation, by the letters of the Greek alphabet, a, b, g, d, e, &c, viz, the most remarkable Star of each by a, the 2d by b, the 3d by g, &c; and when there are more Stars in a constellation than the characters in the Greek alphabet, he denotes the rest, in their order, by the Roman letters A, b, c, d, &c. But as the number of the Stars, that have been observed and registered in catalogues, since Bayer's time, is greatly increased, as by Flamsteed and others, the additional ones have been marked by the ordinal numbers 1, 2, 3, 4, 5, &c.

The Number of Stars. The number of the Stars appears to be immensely great, almost infinite; yet have astronomers long since ascertained the number of such as are visible to the eye, which are much fewer than at first sight could be imagined. See Catalogue of the Stars.

Of the 3000 contained in Flamsteed's catalogue, there are many that are only visible through a telescope; and a good eye scarce ever sees more than a thousand at the same time in the clearest heaven; the appearance of innumerable more, that are frequent in clear winter nights, arising from our sight's being deceived by their twinkling, and from our viewing them confusedly, and not reducing them to any order. But nevertheless we cannot but think the Stars are almost, if not altogether, infinite. See Halley, on the number, order, and light of the fixed Stars, Philos. Trans. number 364, or Abr. vol. 6, pa. 148.

Riccioli, in his New Almagest, affirms, that a man who shall say there are above 20 thousand times 20 thousand, would say nothing improbable. For a good telescope, directed indifferently to almost any point of the heavens, discovers multitudes that are lost to the naked eye; particularly in the milky way, which some take to be an assemblage of Stars, too remote to be seen singly, but so closely disposed as to give a luminous appearance to that part of the heavens where they are. And this fact has been confirmed by Herschel's observations: though it is disputed by others, who contend that the milky way must be owing to some other cause.

In the single constellation of the Pleiades, instead of 6, 7, or 8 Stars seen by the best eye; Dr. Hook, with a telescope 12 feet long, told 78, and with larger glasses many more, of different magnitudes. And F. de Rheita affirms, that he has observed above 2000 Stars in the single constellation of Orion. The same author found above 188 in the Pleiades. And Huygens, looking at the Star in the middle of Orion's sword, instead of one, found it to be 12. Galileo found 80 in the space of the belt of Orion's sword, 21 in the nebulous Star of his head, and above 500 in another part of him, within the compass of one or two degrees space, and more than 40 in the nebulous Star Præsepe.

The Changes that have happened in the Stars are very considerable. The first change that is upon record, was about 120 years before Christ; when Hipparchus, discovering a new Star to appear, was first induced to make a catalogue of the Stars, that posterity might perceive any future changes of the like nature.

In the year 1572, Cornelius Gemma and Tycho Brahe observed another new Star in the constellation Cassiopeia, which was likewise the occasion of Tycho's making a new catalogue. At first its magnitude and brightness exceeded the largest of the Stars, Sirius and Lyra; and even equalled the planet Venus when nearest the earth, and was seen in fair day-light. It continued 16 months; towards the latter end of which it began to dwindle, and at length, in March 1574, it totally disappeared, without any change of place in all that time.

Leovicius tells us of another Star appearing in the same constellation, about the year 945, which resembled that of 1572; and he quotes another ancient observation, by which it appears that a new Star was seen about the same place in 1264. Dr. Keil thinks these were all the same Star; and indeed the periodical intervals, or distance of time between these appearances, were nearly equal, being from 318 to 319 years; and if so, its next appearance may be expected about 1890.

Fabricius, in 1596, discovered another new Star, called the stella mira, or wonderful Star, in the neck of the whale, which has since been found to appear and disappear periodically, 7 times in 6 years, continuing in its greatest lustre for 15 days together; and is never quite extinguished. Its course and motion are described by Bulliald, in a treatise printed at Paris in 1667. Dr. Herschel has lately, viz, in the years 1777, 1778, 1779, and 1780, made several observations on this Star, an account of which may be seen in the Philos. Trans. vol. 70, art. 21.

In the year 1600, William Jansen discovered a changeable Star in the neck of the Swan, which gradually decreased till it became so small as to be thought to disappear entirely, till the years 1657, 1658, and 1659, when it regained its former lustre and magnitude; but soon decayed again, and is now of the smallest size.

In the year 1604, a new Star was seen by Kepler, and several of his friends, near the heel of the right foot of Serpentarius, which was particularly bright and sparkling; and it was observed to be every moment changing into some of the colours of the rainbow, except when it is near the horizon, at which time it was generally white. It surpassed Jupiter in magnitude, but was easily distinguished from him, by the steady light of the planet. It disappeared about the end of the year 1605, and has not been seen since that time.

Simon Marius discovered another in Andromeda's | girdle, in 1612 and 1613: though Bulliald says it had been seen before, in the 15th century.

In July 1670, Hevelius discovered a second changeable Star in the Swan, which was so diminished in October as to be scarce perceptible. In April following it regained its former lustre, but wholly disappeared in August. In March 1672 it was seen again, but appeared very small, and has not been visible since.

In 1686 a third changeable Star was discovered by Kirchius in the Swan, viz, the Star X of that constellation, which returned periodically in about 405 days.

In 1672 Cassini saw a Star in the neck of the Bull, which he thought was not visible in Tycho's time, nor when Bayer made his figures.

It is certain, from the old catalogues, that many of the ancient Stars are not now visible. This has been particularly remarked with regard to the Pleiades.

M. Montanari, in his letter to the Royal Society in 1670, observes that there are now wanting in the heavens two Stars of the 2d magnitude, in the stern of the ship Argo, and its yard, which had been seen till the year 1664. When they first disappeared is not known; but he assures us there was not the least glimpse of them in 1668. He adds, he has observed many more changes in the fixed Stars, even to the number of a hundred. And many other changes of the Stars have been noticed by Cassini, Maraldi, and other observers. See Gregory's Astron. lib. 2, prop. 30.

But the greatest numbers of variable Stars have been observed of late years, and the most accurate observations made on their periods, &c, by Herschel, Goodricke, Pigott, &c, in the late volumes of the Philos. Trans. particularly in the vol. for 1786, where the last of these gentlemen has given a catalogue of all that have been hitherto observed, with accounts of the observations that have been made upon them.

Various hypotheses have been devised to aocount for such changes and appearances in the Stars. It is not probable they could be comets, as they had no parallax, even when largest and brightest. It has been supposed that the periodical Stars have vast dark spots, or dark sides, and very slow rotations on their axes, by which means they must disappear when the darker side is turned towards us. And as for those which break out suddenly with such lustre, these may perhaps be suns whose fuel is almost spent, and again supplied by some of their comets falling upon them, and occasioning an uncommon blaze and splendor for some time; which it is conjectured may be one use of the cometary part of our system.

Maupertuis, in his Dissertation on the figures of the Celestial Bodies (pa. 61—63), is of opinion that some Stars, by their prodigious swift rotation on their axes, may not only assume the figures of oblate spheroids, but that by the great centrifugal force arising from such rotations, they may become of the figures of mill-stones, or be reduced to flat circular planes, so thin as to be quite invisible when their edges are turned towards us, as Saturn's ring is in such position. But when very eccentric planets or comets go round any flat Star in orbits much inclined to its equator, the attraction of the planets or comets in their perihelions must alter the inclination of the axis of that Star; on which account it will appear more or less large and luminous, as its broad side is more or less turned towards us. And thus he imagines we may account for the apparent changes of magnitude and lustre of those Stars, and also for their appearing and disappearing.

Hevelius apprehends (Cometograph. pa. 380), that the Sun and Stars are surrounded with atmospheres, and that by whirling round their axes with great rapidity, they throw off great quantities of matter into those atmospheres, and so cause great changes in them; and that thus it may come to pass that a Star, which, when its atmosphere is clear, shines out with great lustre, may at another time, when it is full of clouds and thick vapours, appear greatly diminished in brightness and magnitude, or even become quite invisible.

Nature of the fixed Stars. The immense distance of the Stars leaves us greatly at a loss about the nature of them. What we can gather for certain from their phenomena, is as follows:

1st, That the fixed Stars are greater than our earth: because if that was not the case, they could not be visible at such an immense distance.

2nd, The fixed Stars are farther distant from the earth than the farthest of the planets. For we frequently find the fixed Stars hid behind the body of the planets: and besides, they have no parallax, which the planets have.

3rd, The fixed Stars shine with their own light; for they are much farther from the Sun than Saturn, and appear much smaller than Saturn; but since, notwithstanding this, they are found to shine much brighter than that planet, it is evident they cannot borrow their light from the same source as Saturn does, viz, the Sun; but since we know of no other luminous body beside the Sun, whence they might derive their light, it follows that they shine with their own native light.

Besides, it is known, that the more a telescope magnifies, the less is the aperture through which the Star is seen; and consequently, the fewer rays it admits into the eye. Now since the Stars appear less in a telescope which magnifies two hundred times, than they do to the naked eye, insomuch that they seem to be only indivisible points, it proves at once that the Stars are at immense distances from us, and that they shine by their own proper light. If they shone by borrowed light, they would be as invisible without telescopes as the satellites of Jupiter are; for the satellites appear larger when viewed with a good telescope than the largest fixed Stars do.

Hence,

1. We deduce, that the fixed Stars are so many suns; for they have all the characters of suns.

2. That in all probability the Stars are not smaller than our sun.

3. That it is highly probable each Star is the centre of a system, and has planets or earths revolving round it, in the same manner as round our sun, i. e. it has opake bodies illuminated, warmed, and cherished by its light and heat. As we have incomparably more light from the moon than from all the Stars together, it is absurd to imagine that the Stars were made for no other purpose than to cast a faint light upon the earth; | especially since many more require the assistance of a good telescope to find them out, than are visible without that instrument. Our sun is surrounded by a system of planets and comets, all which would be invisible from the nearest fixed Star; and from what we already know of the immense distance of the Stars, it is easy to prove, that the sun, seen from such a distance, would appear no larger than a Star of the first magnitude.

From all this it is highly probable, that each Star is a sun to a system of worlds moving round it, though unseen by us; especially as the doctrine of a plurality of worlds is rational, and greatly manifests the power, the wisdom, and the goodness of the great creator.

How immense, then, does the universe appear! Indeed, it must either be infinite, or infinitely near it.

Kepler, it is true, denies that each Star can have its system of planets as ours has; and takes them all to be fixed in the same surface or sphere; urging, that were one twice or thrice as remote as another, it would be twice or thrice as small, supposing their real magnitudes equal; whereas there is no difference in their apparent magnitudes, justly observed, at all. But to this it is opposed, that Huygens has not only shewn, that fires and flames are visible at distances where other bodies, comprehended under equal angles, disappear; but it should likewise seem, that the optic theorem about the apparent diameters of objects, being reciprocally proportional to their distances from the eye, does only hold while the object has some sensible ratio to its distance.

As for periodical Stars, &c. see Changes, &c of Stars, supra.

Motion of the Stars. The fixed Stars have two kinds of apparent motion; one called the first, common, or diurnal motion, arising from the earth's motion round its axis: by this they seem to be carried along with the sphere or firmament, in which they appear fixed, round the earth, from east to west, in the space of 24 hours.

The other, called the second, or proper motion, is that by which they appear to go backwards from west to east, round the poles of the ecliptic, with an exceeding slow motion, as describing a degree of their circle only in the space of 71 1/2 years, or 50 1/3 seconds in a year. This apparent motion is owing to the recession of the equinoctial points, which is 50 1/3 seconds of a degree in a year backward, or contrary to the order of the signs of the zodiac.

In consequence of this second motion, the longitude of the Stars will be always increasing. Thus, for example, the longitude of Cor Leonis was found at different periods, to be as follows: viz,

Year.Long.
By Ptolomy, in 138to be 2°30′
By the Persians, in1115"1730
By Alphonsus, in1364"2040
By Prince of Hesse, in1586"2411
By Tycho, in1601"2417
By Flamsteed, in1690"2531 1/3
Whence the proper motion of the Stars, according to the order of the signs, in circles parallel to the ecliptic, is easily inferred.

It was Hipparchus who first suspected this motion, upon comparing his own observations with those of Timocharis and Aristyllus. Ptolomy, who lived three centuries after Hipparchus, demonstrated the same by undeniable arguments.

The increase of longitude in a century, as stated b<*> different astronomers, is as follows:

ByTycho Brahe25′ 0″
Copernicus12340 1/5
Flamsteed and Riccioli12320
Bulliald12454
Hevelius12446 5/<*>
Dr. Bradley, &c.12355
which is at the rate of 50 1/3 seconds per year.

From these data, the increase in the longitude of a Star for any given time, is easily had, and thence its longitude at any time: ex. gr. the longitude of Sirius, in Flamsteed's tables, for the year 1690, being 9° 49′ 1″, its longitude for the year 1800, is found by multiplying the interval of time, viz, 110 years, by 50 1/3,

the product 5537″, or  1° 32′ 17″, added to the
given longitude  9   49      1
gives the longitude11   21    18 for the year 1800.

The chief phenomena of the fixed Stars, arising from their common and proper motion, besides their longitude, are their altitudes, right ascensions, declinations, occultations, culminations, risings, and settings.

Some have supposed that the latitudes of the Stars are invariable. But this supposition is founded on two assumptions, which are both controverted among astronomers. The one of these is, that the orbit of the earth continues unalterably in the same plane, and consequently that the ecliptic is invariable; the contrary of which is now very generally allowed.

The other assumption is, that the Stars are so fixed as to keep their places immoveably. Ptolomy, Tycho, and others, comparing their observations with those of the ancient astronomers, have adopted this opinion. But from the result of the comparison of our best modern observations, with such as were formerly made with any tolerable degree of exactness, there appears to have been a real change in the position of some of the fixed Stars, with respect to each other; and several Stars of the first magnitude have already been observed, and others suspected to have a proper motion of their own.

Dr. Halley (Philos. Trans. number 355, or Abr. vol. 4, p. 225) has observed, that the three following Stars, the Ball's eye, Sirius, and Arcturus, are now found to be above half a degree more southerly than the ancients reckoned them: that this difference cannot arise from the errors of the transcribers, because the declinations of the Stars, set down by Ptolomy, as observed by Timocharis, Hipparchus, and himself, shew their latitudes given by him are such as those authors intended: and it is scarce to be believed that those three observers could be deceived in so plain a matter. To this he adds, that the bright Star in the shoulder of Orion has, in Ptolomy, almost a whole degree more southerly latitude than at present: that an ancient observation, made at Athens in the year 509, as Bulliald supposes, of an appulse of the moon to the Bull's eye, shews that Star to have had less latitude at that time than it now has: that as to Sirius, it appears by Tycho's observations, that he found him 4 1/2 more northerly | than he is at this time. All these observations, compared together, seem to favour an opinion, that some of the Stars have a proper motion of their own, which changes their places in the sphere of heaven: this change of place, as Dr. Halley observes, may shew itself in so long a time as 1800 years, though it be entirely imperceptible in the space of one single century; and it is likely to be soonest discovered in such Stars as those just now mentioned; because they are all of the first magnitude, and may, therefore, probably be some of the nearest to our solar System. Arcturus, in particular, affords a strong proof of this: for if its present declination be compared with its place, as determined either by Tycho or Flamsteed, the difference will be found to be much greater than what can be suspected to arise from the uncertainty of their observations. See Arcturus, and Mr. Hornsby's enquiry into the quantity and direction of the proper motion of Arcturus, Phil. Trans. vol. 63, part 1, pa. 93, &c.

For an account of Dr. Bradley's observations, see the sequel of this article.

Dr. Herschel has also lately observed, that the diftance of the two Stars forming the double Star g Draconis, is 54″ 48‴, and their position 44° 19′ N. preceding. Whereas, from the right ascension and declination of these Stars in Flamsteed's catalogue, their distance, in his time, appears to have been 1′ 11″ .418, and their position 44° 23′ N. preceding. Hence he infers, that as the difference in the distance of these two Stars is so considerable, we can hardly account for it, otherwise than by admitting a proper motion in one or the other of the Stars, or in our solar system: most probably he says, neither of the three is at rest. He also suspects a proper motion in one of the double Stars, in Cauda Lyncis Media, and in <*> Ceti. Phil. Trans. vol. 72, part 1, p. 117, 143, 150.

It is reasonable to expect, that other instances of the like kind must also occur among the great number of visible Stars, because their relative positions may be altered by various means. For if our own solar system be conceived to change its place with respect to absolute space, this might, in process of time, occasion an apparent change in the angular distances of the fixed Stars; and in such a case, the places of the nearest Stars being more affected than of those that are very remote, their relative position might seem to alter, though the Stars themselves were really immoveable; and vice versa, we may surmise, from the observed motion of the Stars, that our sun, with all its planets and comets, may have a motion towards some particular part of the heavens, on account of a greater quantity of matter collected in a number of Stars and their surrounding planets there situated, which may perhaps occasion a gravitation of our whole solar system towards it. If this surmise should have any foundation, as Dr. Herschel observes, ubi supra, p. 103, it will shew itself in a series of some years; since from that motion there will arise another kind of hitherto unknown parallax (suggested by Mr. Michell, Philos. Trans. vol. 57, p. 252), the investigation of which may account for some part of the motions already observed in some of the principal Stars; and for the purpose of determining the direction and quantity of such a motion, accurate observations of the distance of Stars, that are near enough to be measured with a micrometer, and a very high power of telescopes, may be of considerable use, as they will undoubtedly give us the relative places of those Stars to a much greater degree of accuracy than they can be had by instruments or sectors, and thereby much sooner enable us to discover any apparent change in their situation, occasioned by this new kind of secular or systematical parallax, if we may so express the change arising from the motion of the whole solar system.

And, on the other hand, if our system be at rest, and any of the Stars really in motion, this might likewise vary their apparent positions; and the more so, the nearer they are to us, or the swifter their motions are; or the more proper the direction of the motion is to be rendered perceptible by us. Since then the relative places of the Stars may be changed from such a variety of causes, considering the amazing distance at which it is certain some of them are placed, it may require the observations of many ages to determine the laws of the apparent changes, even of a single Star; much more difficult, therefore, must it be to settle the laws relating to all the most remarkable Stars.

When the causes which affect the places of all the Stars in general are known; such as the precession, aberration, and nutation, it may be of singular use to examine nicely the relative situations of particular Stars, and especially of those of the greatest lustre, which, it may be presumed, lie nearest to us, and may therefore be subject to more sensible changes, either from their own motion, or from that of our system. And if, at the same time the brighter Stars are compared with each other, we likewise determine the relative positions of some of the smallest that appear near them, whose places can be ascertained with sufficient exactness, we may perhaps be able to judge to what cause the change, if any be observable, is owing. The uncertainty that we are at present under, with respect to the degree of accuracy with which former astronomers could observe, makes us unable to determine several things relating to this subject; but the improvements, which have of late years been made in the methods of taking the places of the heavenly bodies, are so great, that a few years may hereafter be sufficient to settle some points, which cannot now be settled; by comparing even the earliest observations with those of the present age.

Dr. Hook communicated several observations on the apparent motions of the fixed Stars; and as this was a matter of great importance in astronomy, several of the learned were desirous of verifying and confirming his observations. An instrument was accordingly contrived by Mr. George Graham, and executed with surprising exactness.

With this instrument the Star g, in the constellation Draco, was frequently observed by Messrs. Molyneux, Bradley, and Graham, in the years 1725, 1726; and the observations were afterwards repeated by Dr. Bradley with an instrument contrived by the same ingenious person, Mr. Graham, and so exact, that it might be depended on to half a second. The result of these observations was, that the Star did not always appear in the same place, but that its distance from the zenith varied, and that the difference of the apparent places amounted to 21 or 22 seconds. Similar observations were made on other Stars, and a like apparent motion | was found in them, proportional to the latitude of the Star. This motion was by no means such as was to have been expected, as the effect of a parallax, and it was some time before any way could be found of accounting for this new phenomenon. At length Dr. Bradley resolved all its variety, in a satisfactory manner, by the motion of light and the motion of the earth compounded together. See Light, and Phil. Trans. No. 406, p. 364, or Abr. vol. vi, p. 149, &c.

Our excellent astronomer, Dr. Bradley, had no sooner discovered the cause, and settled the laws of aberration of the fixed Stars, than his attention was again excited by another new phenomenon, viz, an annual change of declination in some of the fixed Stars, which appeared to be sensibly greater than a precession of the equinoctial points of 50″ in a year, the mean quantity now usually allowed by astronomers, would have occasioned.

This apparent change of declination was observed in the Stars near the equinoctial colure, and there appearing at the same time an effect of a quite contrary nature, in some Stars near the solstitial colure, which seemed to alter their declination less than a precession of 50″ required, Dr. Bradley was thereby convinced, that all the phenomena in the different Stars could not be accounted for merely by supposing that he had assumed a wrong quantity for the precession of the equinoctial points. He had also, after many trials, sufficient reason to conclude, that these second unexpected deviations of the Stars were not owing to any imperfection of his instruments. At length, from repeated observations he began to guess at the real cause of these phenomena.

It appeared from the Doctor's observations, during his residence at Wansted, from the year 1727 to 1732, that some of the Stars near the solstitial colure had changed their declinations 9″ or 10″ less than a precession of 50″ would have produced; and, at the same time, that others near the equinoctial colure had altered theirs about the same quantity more than a like precession would have occasioned: the north pole of the equator seeming to have approached the Stars, which come to the meridian with the sun about the vernal equinox, and the winter solstice; and to have receded from those, which come to the meridian with the sun about the autumnal equinox and the summer solstice.

From the consideration of these circumstances, and the situation of the ascending node of the moon's orbit when he first began to make his observations, he suspected that the moon's action upon the equatorial parts of the earth might produce these effects.

For if the precession of the equinox be, according to Sir Isaac Newton's principles, caused by the actions of the sun and moon upon those parts; the plane of the moon's orbit being, at one time, above 10 degrees more inclined to the plane of the equator than at another, it was reasonable to conclude, that the part of the whole annual precession, which arises from her action, would, in different years, be varied in its quantity; whereas the plane of the ecliptic, in which the sun appears, keeping always nearly the same inclination to the equator, that part of the precession, which is owing to the sun's action, may be the same every year; and from hence it would follow, that although the mean annual precession, proceeding from the joint actions of the sun and moon, were 50″; yet the apparent annual precession might sometimes exceed, and sometimes fall short of that mean quantity, according to the various situations of the nodes of the moon's orbit.

In the year 1727, the moon's ascending node was near the beginning of Aries, and consequently her orbit was as much inclined to the equator as it can at any time be; and then the apparent annual precession was found, by the Doctor's first year's observations, to be greater than the mean; which proved, that the Stars near the equinoctial colure, whose declinations are most of all affected by the precession, had changed theirs, above a tenth part more than a precession of 50″ would have caused. The succeeding year's observations proved the same thing; and, in three or four years' time, the difference became so considerable as to leave no room to suspect it was owing to any imperfection either of the instrument or observation.

But some of the Stars, that were near the solstitial colure, having appeared to move, during the same time, in a manner contrary to what they ought to have done, by an increase of the precession; and the deviations in them being as remarkable as in the others, it was evident that something more than a mere change in the quantity of the precession would be requisite to solve this part of the phenomenon. Upon comparing the observations of Stars near the solstitial colure, that were almost opposite to each other in right ascension, they were found to be equally affected by this cause. For whilst g Draconis appeared to have moved northward, the small Star, which is the 35th Camelopardali Hevelii, in the British catalogue, seemed to have gone as much towards the south; which shewed, that this apparent motion in both those Stars might proceed from a nutation of the earth's axis; whereas the comparison of the Doctor's observations of the same Stars formerly enabled him to draw a different conclusion, with respect to the cause of the annual aberrations arising from the motion of light. For the apparent alteration in g Draconis, from that cause, being as large again as in the other small Star, proved, that that did not proceed from a nutation of the earth's axis; as, on the contrary, this may.

Upon making the like comparison between the observations of other Stars, that lie nearly opposite in right ascension, whatever their situations were with respect to the cardinal points of the equator, it appeared, that their change of declination was nearly equal, but contrary; and such as a nutation or motion of the earth's axis would effect.

The moon's ascending node being got back towards the beginning of Capricorn in the year 1732, the Stars near the equinoctial colure appeared about that time to change their declinations no more than a precession of 50″ required; whilst some of those near the solstitial colure altered theirs above 2″ in a year less than they ought. Soon after the annual change of declination of the former was perceived to be diminished, so as to become less than 50″ of precession would cause, and it continued to diminish till the year 1736, when the moon's ascending node was about the beginning of Libra, and her orbit had the least inclination to the equator. But by this time, some of the Stars near the solstitial colure had altered their declinations 18″ | less since the year 1727, than they ought to have done from a precession of 50″. For g Draconis, which in those 9 years would have gone about 8″ more southerly, was observed, in 1736, to appear 10″ more northerly than it did in the year 1727.

As this appearance in g Draconis indicated a diminution of the inclination of the earth's axis to the plane of the ecliptic, and as several astronomers have supposed that inclination to diminish regularly; if this phenomenon depend upon such a cause and amounted to 18″ in 9 years, the obliquity of the ecliptic would, at that rate, alter a whole minute in 30 years; which is much faster than any observations before made would allow. The Doctor had therefore reason to think, that some part of this motion at least, if not the whole, was owing to the moon's action on the equatorial parts of the earth, which he conceived might cause a libratory motion of the earth's axis. But as he was unable to judge, from only 9 years observation, whether the axis would entirely recover the same position that it had in the year 1727, he found it necessary to continue his observations through a whole period of the moon's nodes; at the end of which he had the satisfaction to see, that the Stars returned into the same positions again, as if there had been no alteration at all in the inclination of the earth's axis; which fully convinced him, that he had guessed rightly as to the cause of the phenomenon. This circumstance proves likewise, that if there be a gradual diminution of the obliquity of the ecliptic, it does not arise only from an alteration in the position of the earth's axis, but rather from some change in the plane of the ecliptic itself; because the Stars, at the end of the period of the moon's nodes, appeared in the same places, with respect to the equator, as they ought to have done if the earth's axis had retained the same inclination to an invariable plane.

The Doctor having communicated these observations, and his suspicion of their cause, to the late Mr. Machin, that excellent geometrician soon after sent him a table, containing the quantity of the annual precession in the various positions of the moon's nodes, as also the corresponding nutations of the earth's axis; which was computed upon the supposition that the mean annual precession is 50″, and that the whole is governed by the pole of the moon's orbit only; and therefore Mr. Machin imagined, that the numbers in the table would be too large, as, in fact, they were found to be. But it appeared that the changes which Dr. Bradley had observed, both in the annual precession and nutation, kept the same law, as to increasing and decreasing, with the numbers of Mr. Machin's table. Those were calculated on the supposition, that the pole of the equator, during a period of the moon's nodes, moved round in the periphery of a little circle, whose centre was 23° 29′ distant from the pole of the ecliptic; having itself also an angular motion of 50″ in a year about the same pole. The north pole of the equator was conceived to be in that part of the small circle which is farthest from the north pole of the ecliptic at the same time when the moon's ascending node is in the beginning of Aries; and in the opposite point of it, when the same node is in Libra.

If the diameter of the little circle, in which the pole of the equator moves, be supposed equal to 18″, which is the whole quantity of the nutation, as collected from Dr. Bradley's observations of the Star g Draconis, then all the phenomena of the several Stars which he observed will be very nearly solved by this hypothesis. But for the particulars of his solution, and the application of his theory to the practice of astronomy, we must refer to the excellent author himself; our intention being only to give the history of the invention.

The corrections arising from the aberration of light, and from the nutation of the earth's axis, must not be neglected in astronomical observations; since such neglects might produce errors of near a minute in the polar distance of some Stars.

As to the allowance to be made for the aberration of light, Dr. Bradley assures us, that having again examined those of his own observations, which were most proper to determine the transverse axis of the ellipsis, which each Star seems to describe, he found it to be nearest to 40″; and this is the number he makes use of in his computations relating to the nutation.

Dr. Bradley says, in general, that experience has taught him, that the observations of such Stars as lie nearest the zenith, generally agree best with one another, and are therefore fittest to prove the truth of any hypothesis. Phil. Trans. N°. 485, vol. 45, p. 1, &c.

Monsieur d'Alembert has published a treatise, entitled, Recherches sur la Precession des Equinoxes, et sur la Nutation de la Terre dans le Systeme Newtonien, 4to. Paris, 1749. The calculations of this learned gentleman agree in general with Dr. Bradley's observations. But Monsieur d'Alembert finds, that the pole of the equator describes an ellipsis in the heavens, the ratio of whose axes is that of 4 to 3; whereas, according to Dr. Bradley, the curve described is either a circle or an ellipsis, the ratio of whose axes is as 9 to 8.

The several Stars in each constellation, as in Taurus, Bootes, Hercules, &c, see under the proper article of each constellation, Taurus, Bootes, Hercules, &c.

To learn to know the several fixed Stars by the globe, see Globe.

The parallax and distance of the fixed Stars, see under Parallax and Distance.

Circumpolar Stars. See Circumpolar.

Morning Star. See Morning.

Place of a Star. See Place.

Pole Star. See Pole.

Twinkling of the Stars. See Twinkling.

Unformed Stars. See Informes.

The following two catalogues of Stars are taken from Dr. Zach's Tabulæ Motuum Solis &c, and are adapted to the beginning of the year 1800. The former contains 381 Stars, shewing their names and Bayer's mark, their magnitude, declination, and right ascension, both in time and in arcs or degrees of a great circle, with the annual variations of the same. And the latter contains 162 principal Stars, shewing their declinations to seconds of a degree, with their annual variations. The explanations are sufficiently clear from the titles of the columns. |

A Catalogueof the most remarkableFixed Stars, with their Magnitudes, Right Ascensions, Declinations and Annual Variations, for the Beginning of the Year 1800.
No. of Stars.Names and Characters of the Stars.Magni- tude.Right Ascens. in time.Annual Variat. in ditto.Right Ascension in degrees &c.Annual Variat. in ditto.Declination North and South.Annual Variat. in ditto.
    h.m.s. 1/100s 1/1000°″ 1/100″ 1/100°  
       +   +     
1gPegasi20256.793.06304411.8545.95144N
2<*>Ceti30513.513.05921822.6645.89957S
3kCassiopeæ402145.123.30152616.7549.516150N
4zCassiopeæ402553.933.26262829.0148.935249N
5dAndromedæ302839.023.1617945.3147.422945N
6aCassiopeæ302914.403.31171835.9549.665526N
7bCeti2 303331.833.00182257.4045.01195S
8hCassiopeæ40371.443.38991521.6450.835646N
9dPiscium403819.083.09393446.1546.39630N
10gCassiopeæ304444.753.505111111.2952.585938N
11ePiscium405233.953.10313829.2046.55649N
12bAndromedæ205834.233.297143833.3849.463433N
13<*>Cassiopeæ40590.223.53114453.3352.965335N
14zPiscium41316.993.109154914.8046.63631N
15dCassiopeæ311250.583.761181238.7056.425911N
16mPiscium511942.073.108195531.0746.6257N
17pPiscium513030.703.164223740.5647.46117N
18nPiscium4 51311.773.107224526.6246.61428N
19oPiscium4 513450.723.144234240.8447.1689N
20eCassiopeæ314010.014.15525230.1362.336241N
21zCeti314136.692.953252410.3344.301120S
22aTriang. Bor.3 414142.743.379252541.1550.682836N
23g′Arietis414234.523.258253837.7348.871819N
24bArietis314336.773.277255411.4849.151950N
25lArietis514648.863.315264212.8349.732237N
26gAndromedæ215141.053.615275515.7654.234122N
27*preced. a *y.15026.15.....273632.25. . .....
28aArietis215555.273.335285849.0550.022231N
29*seq. a *y.15938.13. . .295431.95. . .....
30<*>1Arietis5 6271.643.308314524.5549.621858N
31oCeti (Variab.)22914.703.019321840.5045.29354S
32Arietis62389.293.321393219.3249.811638N
33sArietis624028.093.2854071.3949.281415N
34dCeti322914.173.060371832.5445.90033S
35eCeti322953.422.884372821.3743.271244S
36gCeti323257.183.102381417.7646.53223N
37pCeti323436.022.84938390.2942.741443S
38*yYLilii Bor.423557.703.521385925.4952.812825N
39*yLilii Aust.423814.433.489393336.4952.342626N
40r2Arietis624435.653.34441854.7250.161731N
41r3Arietis5 62459.353.340411720.1950.101713N
42hEridani324639.722.917413955.7843.75942S
43eArietis524748.013.40141571.8051.012032N
44gPersei325024.424.25042366.2563.755243N
45aCeti225150.073.119425731.0646.66318N
|
Catalogue of the principal Fixed Stars for the Beginning of the Year 1800.
No. of Stars.Names and Characters of the Stars.Magni- tude.Right Ascens. in time.Annual Variat. in ditto.Right Ascens. in degrees. &c.Annual Variat. in ditto.Declination North and South.Annual Variat. in ditto.
    h.m.s. 1/100s 1/1000°″ 1/100″ 1/100°  
       +   +     
46*seq. a Ceti.25154.61. . .425839.15. . .. . . .
47bPersei2 325512.073.84643481.0457.694011N
48dArietis43012.713.39345310.5950.891858N
49zArietis53325.983.422455129.7751.332018N
50zEridani3367.482.904463152.2043.56934S
51t1Arietis73942.363.433472535.3951.492025N
52aPersei23106.854.203473142.7763.05498N
53t2Arietis631116.373.42847495.4851.42201N
5465Arietis731255.523.430481352.7451.45205N
55fTauri531954.653.289495739.7849.331215N
56eEridani3 432331.522.883505252.8443.24109S
57dPersei332844.934.203521113.9163.05478N
58hLucida Plei.333537.173.535535417.5653.032329N
59zPersei334135.203.734552348.0056.013117N
60ePersei334429.193.97756717.8759.663925N
61gEridani2 334842.252.786571033.7741.79145S
62ATauri535253.463.515581321.8352.722132N
63gTauri34825.233.38762618.4850.80158N
64d1Tauri3 441124.683.432625110.2651.48174N
65d2Tauri441234.933.43163843.8951.461658N
66k1Tauri541327.663.545632154.9353.172150N
67k2Tauri4 541331.133.543632247.0253.142144N
68eTauri3 441656.983.475641414.7652.121844N
69<*>1Tauri54179.303.401641719.5351.021531N
70<*>2Tauri541719.533.399641952.9150.991525N
71*præced. a <*>.42212.56. . .65338.40. . .. . . .
72Aldebaran142427.293.42166649.3851.31166N
73*sequ. a <*>.42643.44. . .664051.60. . .. . . .
74s2Tauri642744.783.406665611.7751.091524N
75u2Eridani3 442747.262.329665648.8334.943059S
76s2Tauri642750.673.409665740.8751.131531N
77Eridani3 443143.152.615675547.2139.23204S
78<*>Tauri44519.383.565724720.7553.472118N
79bEridani34582.382.948743035.7444.22521S
80lEridani445934.732.863745340.9542.9591S
81*præc. a Aurig..5139.44. . .752451.60. . .. . . .
82Capella15156.164.41475292.4066.214547N
83*seq. a Aurig..5314.28. . .754834.20. . .. . . .
84*præc. b Orio..5356.39. . .75595.85. . .. . . .
85Rigel15455.542.867761353.1043.01827S
86*seq. b Orionis.5824.57. . .7768.55. . .. . . .
87bTauri251339.383.778782450.7056.672826N
88gOrionis251424.543.20978368.1648.1369N
89bLeponis3 451941.092.565795516.4038.472056S
90dOrionis252147.383.057802653.6945.86028S
|
Catalogue of the principal Fixed Stars for the Beginning of the Year 1800.
No. of Stars.Names and Characters of the Stars.Mag. nitude.Right Ascens. in time.Annual Variat. in ditto.Right Ascension in degrees, &c.Annual Variat. in ditto.Declination North and South.Annual Variat. in ditto.
    h.m.s. 1/100s. 1/1000°″ 1/100″ 1/100°  
       +   +     
91aLeporis352354.942.639805844.1339.591759S
92zTauri352542.413.575812536.1453.62210N
93eOrionis25264.153.03781312.1945.55120S
94z*>Orionis253040.573.02082408.5745.3024S
95aColumbæ253225.032.16783615.4532.503411S
96gLeporis3 45369.022.51784215.3437.752231S
97kOrionis453816.282.83984344.2142.59945S
98*præc. a Orio..54127.74. . .852156.10. . ....
99aOrionis154420.573.2398658.5548.59721N
100*seq. a Orionis.54735.59. . .865823.85. . ....
101bAurigæ2 354451.684.398861255.2265.974455N
102HGemin. (prop.)4 555157.723.642875925.7754.632316N
103hGeminorum3 46248.293.62390424.3454.342233N
104mGeminorum361051.443.624924251.6454.362236N
105zCanis majoris361239.082.29893946.2434.472959S
106bCanis majoris2 361353.762.638932826.3339.571752S
107nGeminorum46175.483.562941622.2253.432020N
108gGeminorum2 36269.353.463963220.3251.951634N
109eGeminorum363137.343.695975420.0555.422519N
110*præc. a Can. maj..62941.80. . .972527.00. . ....
111Sirius163619.912.64799458.6539.711626S
112*seq. a Can. maj..64126.68. . .1002140.20. . ....
113eCanis majoris2 365046.212.3541024133.2035.312843S
114zGeminorum3 465214.553.567103338.2453.472051N
115dCanis majoris2 37015.392.436105353.8536.54265S
116dGeminorum37810.063.594107230.9452.912220N
117bCanis minoris371618.013.261109430.2148.92841N
118*præc. a Gemin..71613.66. . .109324.90. . ....
119Castor1 272148.813.8551102712.1557.833219N
120*seq. a Gemin..7274.84. . .1114612.60. . ....
121uGeminorum4 572334.543.7151105338.0455.722721N
122*præc. aCan. min..72640.27. . .111404.05. . ....
123Procyon1 272849.103.1371121216.5047.06544N
124*seq. a Can. min..73027.12. . .1123646.80. . ....
125Pollux27333.183.6871131547.7055.312830N
126*seq. b Gemin..73528.78. . .1135211.70. . ....
127m2Cancri575557.643.5451185924.5553.18229N
128y2Cancri475823.253.6391193548.7354.58267N
129bCancri3 48539.373.2661212450.6148.99948N
130<*>Cancri5 6′82010.353.441125235.3151.611846N
131hCancri6 78217.793.4911251656.8752.36216N
132dHydræ48273.043.1891264545.5347.83623N
133gCancri483141.863.4991275527.8552.492210N
134dCancri483318.113.4281281931.7051.421853N
135eHydræ483610.143.199129232.0347.9878N
|
Catalogue of the principal Fixed Stars for the Beginning of the Year 1800.
No. of Stars.Names and Characters of the Stars.Magni- tude.Right Ascens. in time.Annual Variat. in ditto.Right Ascension in degrees, &c.Annual Variat. in ditto.Declination North and South.Annual Variat. in ditto.
    h.m.s. 1/100s. 1/1000°″ 1/100″ 1/100°  
       +   +     
136zHydræ4 584448.863.1871311212.8447.81642N
137a1Cancri4 584459.393.2901311450.8149.351224N
138a2Cancri3 484731.823.2921315257.2649.381237N
139kCancri4 585654.333.2631341334.9248.951128N
140c1Cancri5 685830.373.4721342735.4852.082251N
141<*>Hydræ49354.803.1201355842.0346.80310N
142kLeonis491258.323.5241381434.7752.86272N
143Alphard291744.972.9351392614.5544.03748S
144*seq. a Hydræ.9239.19. . .1404717.85. . ....
145cLeonis49219.263.2531401718.9748.801211N
146oLeonis493027.653.2241423654.8248.361048N
147eLeonis393428.293.434143374.3151.512441N
148mLeonis394121.843.4571452027.5451.852657N
149nLeonis494726.923.2431465143.7648.651324N
150pLeonis494937.993.1831472429.8947.7590N
151hLeonis3 495224.603.28914969.0449.331744N
152Regulus195742.023.2041492530.3048.061256N
153*seq. a Leonis.10428.58. . .15178.70. . ....
154zLeonis310532.343.361151235.1650.422425N
155g2Leonis2 310855.223.3061521348.2349.602051N
156mUrsæ majoris3101021.353.6351523523.3254.524230N
157rLeonis4102215.773.1701553356.4947.551020N
158bUrsæ majoris2104939.533.7091622454.9355.635727N
159aCrateris410504.552.943162318.2544.141714S
160aUrsæ majoris1 2105115.843.8471624857.6157.706250N
161bCrateris3 411150.062.9331652730.9744.023144S
162dLeonis2 311326.393.1991655135.9147.982137N
163<*>Leonis311344.233.165165563.4947.481631N
164lCrateris5 6111328.152.981168222.2144.721717S
165iLeonis4111328.323.125168224.8546.871138N
166tLeonis4111739.493.0851692452.3446.28357N
167uLeonis4112642.823.0691714042.2946.04017N
168nVirginis5113534.113.0871735351.7046.31739N
169*præc. b Leonis.113819.46. . .1743451.90. . ....
170Denebola1 2113850.493.0621744237.3545.931541N
171bVirginis3114016.383.12217545.7046.83254N
172gUrsæ majoris2114314.223.2121754833.3348.185448N
173aCorvi411586.943.0621793144.1045.932337S
174eCorvi4115951.633.0671795754.4746.002130S
175dUrsæ majoris312527.233.0211812148.4245.32589N
176gCorvi312532.313.077181234.5846.161626S
177hVirginis312940.743.0671822511.1346.01027N
178bCorvi3122354.393.1241855835.9246.862217S
179kDraconis3122447.652.6611861154.7239.917053N
180g1Virginis3123133.853.0691875327.7246.03021S
|
Catalogue of the principal Fixed Stars for the Beginning of the Year 1800.
No. of Stars.Names and Characters of the Stars.Mag. nitude.Right Ascens. in time.Annual Variat. in ditto.Right Ascens. in degrees. &c.Annual Variat. in ditto.Declination North and South.Annual Variat. in ditto.
    h.m.s. 1/100s. 1/1000°″ 1/100″ 1/100°  
       +   +     
181eUrsæ majoris2 3124512.582.746191188.6741.19573N
182dVirginis3124533.663.0471912324.9345.71429N
183eVirginis3125213.333.004193320.0145.06122N
184<*>Virginis3 4125936.463.095194546.9746.42428S
185gHydræ31384.313.22519714.6448.38227S
186*præc. a Virg.13913.00. . .1971815.00. . ....
187Spica1131440.113.137198401.6647.06107S
188zUrsæ majoris3131549.622.4251985724.2636.375559N
189iVirginis4131610.793.129199241.8346.931140S
190zVirginis3132430.653.064201739.6845.96025N
191tBootis4133746.362.8842042635.3543.261827N
192hUrsæ majoris2 3133938.852.3552045442.8035.885019N
193hBootis313459.212.8602061718.1242.901925N
194aDraconis2 3135858.881.6282094443.2424.426520N
195kVirginis414214.873.1792103343.0447.68920S
196Arcturus114632.212.722211383.1640.832015N
197*seq. a Bootis.14636.46. . .211396.90. . ....
198lVirginis414819.143.223212447.1648.351227S
199gBootis314241.502.428216022.5436.423911N
200zBootis3143135.562.8542175353.4242.811436N
201eBootis3143614.992.612219344.8039.332756N
202mLibræ5143822.953.2682193544.2249.021318S
203a1Libræ6143938.743.2992195441.1049.49159S
204*præc. a2 .143938.77. . .2195441.55. . ....
205a2Libræ2 3143949.973.2892195729.5549.341512S
206bUrsæ minoris3145127.55-0.3292225153.19-4.947459N
207gScorpii3145224.353.48222365.2252.232429S
208bBootis3145424.992.2622233614.8533.934111N
209yBootis5145552.502.580223587.5738.702744N
210bLibræ2 315615.613.2152263354.2148.22838S
211dBootis315726.622.4092265139.2836.13344N
212oCoron. bor.6151151.972.4872275759.5537.303021N
213hCoron. bor.5151456.052.465228440.7836.97311N
214bCoron. bor.4151934.882.4832295343.1337.242948N
215g2Ursæ minoris2 3152111.76-0.2092301756.39-3.147233N
216z4Libræ3 4152138.423.3652302436.2650.481610S
217gLibræ4152421.223.328231518.3449.92147S
218dSerpentis3152515.842.8612311857.6142.911113N
219Gemma2152613.292.5432313319.3538.152724N
220kLibræ4153027.123.4332323646.7751.49191S
221aSerpentis2153425.212.9362233618.0044.0474N
222*seq. a Serpentis.153623.53. . .234553.05. . ....
223bSerpentis3153657.702.7562341425.4741.34164N
224mSerpentis4153910.303.0232344734.5545.35248S
225eSerpentis3 4154050.972.9692351244.5144.5456N
|
Catalogue of the principal Fixed Stars for the Beginning of the Year 1800.
No. of Stars.Names and Characters of the Stars.Magni- tude.Right Ascens. in time.Annual Variat. in ditto.Right Ascension in degrees, &c.Annual Variat. in ditto.Declination North and South.Annual Variat. in ditto.
    h.m.s. 1/100s. 1/1000°″ 1/100″ 1/100°  
       +   +     
226dCoron. bor.4154112.452.515235186.7137.732642N
227lLibræ4154144.863.4572352612.9351.861933S
228<*>Scorpii3 4154433.343.671236820.0655.062837S
229pScorpii3154646.433.6002364136.4854.002531S
230yLibræ415470.913.3392364513.6350.091341S
231gSerpentis3154712.932.7402364813.9841.101621N
232dScorpii3154831.893.521237758.3852.82222S
233eCoron. bor.4 5154918.542.4832371938.0437.242728N
234pSerpentis4155341.182.5762382517.7238.642321N
235bScorpii2155349.713.4652382725.6551.971915S
236<*>Draconis3 415588.281.142239324.2717.13596N
237nScorpii416023.313.465240549.6051.961856S
238dOphiuchi316352.803.1322405811.9546.98310S
239eOphiuchi3 416745.093.1542415616.3147.30412S
240gHerculis316135.832.6422431627.4139.631938N
241Antares116179.693.6452441725.3554.682558S
242* aScorpii.16196.66. . .2444639.90. . ....
243fOphiuchi4 5161943.033.4182445545.4251.271610S
244hDraconis3 4162118.330.7852451934.9211.786158N
245bHerculis3162137.872.5792452428.0838.682156N
246tScorpii4162326.963.7092455144.3655.642747S
247zOphiuchi2 316269.553.2872463223.2449.30109S
248zHerculis3 4163345.642.2922482624.6734.38321N
249hHerculis3 416363.142.046249047.1530.693919N
250eHerculis3165238.682.292253940.1634.383116N
251hOphiuchi2 3165855.153.4242544347.2651.361528S
252*præc. a Herc..17512.70. . .2561810.50. . ....
253aHerculis2 317531.762.7262562256.4040.891438N
254dHerculis3 417649.412.4592564221.1736.88255N
255<*>Ophiuchi317944.253.669257263.6855.042447S
256lScorpii317202.644.057260039.5860.853657S
257*præc. a Ophi..172445.90. . .2611128.50. . ....
258aOphiuchi2172538.972.7682612444.5541.521743N
259*seq. a Ophi..172911.02. . .2621745.32. . ....
260bDraconis3172555.991.3482612859.8220.225227N
261bOphiuchi3173335.772.9592632356.5444.39440N
262gOphiuchi3173752.043.003264280.5645.05248N
263zSerpentis3 4174954.593.1532672838.874<*>.30340S
264oOphiuchi4175037.472.9992673921.9944.99257N
265gDraconis2 3175157.791.3892675926.8520.835131N
266gSagittarii3 4175258.053.8512681430.7657.773025S
267bTaur. Poniat..18041.102.9932701016.5044.90319N
268m1Sagittarii418148.373.584270275.6353.76216S
269m2Sagittarii4 618316.903.5752704913.5753.622046S
270eSagittarii2 3181053.673.9842724325.1159.763428S
|
Catalogue of the principal Fixed Stars for the Beginning of the Year 1800.
No. of Stars.Names and Characters of the Stars.Magni- tude.Right Ascens. in time.Annual Variat. in ditto.Right Ascens. in degrees, &c.Annual Variat. in ditto.Declination North and South.Annual Variat. in ditto.
    h.m.s. 1/100s. 1/1000°″ 1/100″ 1/100°  
       +   +     
271lSagittarii4181537.663.7052735424.9255.572531S
272*præc. a Lyræ.182840.12. . .277101.88. ....
273Wega118309.891.9942773228.3529.913836N
274*seq. a Lyræ.183140.00. . .2775450.00. ....
275fSagittarii3 418339.393.7472781720.8456.212711S
276eLyræ5183742.871.9832792543.0329.743928N
277n1Sagittarii4 518425.413.6252803121.2254.382259S
278bLyræ3184241.862.2112804027.8933.16339N
279sSagittarii3184251.403.7242804250.9955.862632S
280n2Sagittarii4 518431.133.6232804516.9954.352254S
281<*>Serpentis3184616.822.9772813412.3544.66357N
18.3234.84
282dLyræ3 4184731.162.0952815247.4331.423639N
283oDraconis4184814.150.880282332.2013.21599N
284gLyræ3185127.042.2412825145.5533.613226N
285oSagittarii4185241.183.5952831017.7253.92221S
286tSagittarii4185426.453.7582833636.8256.372757S
287lAntinoi3 4185538.103.1862835431.5547.79510S
288zAquilæ3185612.692.755284310.3741.331335N
289pSagittarii3 4185751.373.5742842750.5753.612120S
290ySagittarii4 519315.273.6852854849.0455.272535S
291dSagittarii4 619555.863.5172862857.9052.761918S
292dDraconis3191227.950.033288659.210.496719N
293kCygni4191228.281.38328874.1920.735258N
294dAquilæ3191524.123.008288511.7945.12244N
295<*>Cygni3192238.532.4152903937.9730.232733N
296<*>Cygni4 6192439.611.511291954.1922.675119N
297<*>Antinoi3 4192622.163.1062913532.3746.59143S
298<*>Cygni419315.161.6452024617.4024.684946N
299aSagittæ419319.252.6782924718.7440.171734N
300fSagittarii6193441.433.5202934021.3952.802014S
301*præc. g Aquilæ.193512.50. . .293487.50. . ....
302gAquilæ3193644.502.837294117.5042.59108N
303*seq. g Aquilæ.19390.81. . .2944512.16. . ....
304dCygni3193843.091.8692944046.3428.024439N
305*præc. a Aquilæ.193835.87. . .2943858.05. . ....
306Atair1 219411.022.9182951515.3043.78821N
307*seq. a Aquilæ.194252.37. . .295435.55. . ....
308hAntinoi3 4194217.143.0582953417.0845.87030N
309bSagittarii4 5194439.563.699296953.4655.482741S
310bAquilæ3 4194528.972.9392962214.5544.08555N
311<*>Aquilæ320058.523.0973001437.<*>46.45124S
312a1Capricorni3 420632.703.3303013811.8849.95137S
313*præc. a2 Capri..20517.48. . .3011922.20. . ....
314a2Capricorni320656.483.331301447.2049.96139S
315*seq. a2 Capri..20933.32. . .3022319.80. . ....
|
Catalogue of the principal Fixed Stars for the Beginning of the Year 1800.
No. of Stars.Names and Characters of the Stars.Magni- tude.Right Ascens. in time.Annual Variat. in ditto.Right Ascens. in degrees, &c.Annual Variat. in ditto.Declination North and South.Annual Variat. in ditto.
    h.m.s. 1/100s. 1/1000°″ 1/100″ 1/100°  
       +         
316bCapricorni.20931.352.3803022250.1950.701524S
317nCapricorni620933.693.3373022325.3950.061323S
318bCapricorni320945.503.3803022622.5450.701524S
319gCygni320152.632.1483034539.3932.223938N
320<*>Capricorni6201726.453.4383042136.7251.571828S
321zDelphini4 5202557.502.8013062922.4442.01140N
322bDelphini3202810.322.804307234.7442.061355N
323aDelphini3203020.762.7803073511.3741.701513N
324Deneb.1 2203436.682.0343083910.2030.514434N
325*seq. a Cygni.204028.55. . .31078.25. . ....
326eAquarii4 5203650.383.2553091235.7248.831013S
327*præc. g Delphini.203721.94. . .3092029.08. . ....
328gDelphini3203722.962.7833092044.3441.751525N
329eCygni320386.702.3933093140.5635.893313N
330mAquarii4 5204151.173.2333102747.6148.65943S
331Aquarii620464.593.255311318.8048.821028S
332<*>Capricorni5 4205439.753.3843133956.2550.76181S
333nAquarii5205841.243.2743144018.6449.111210S
334aEquulei421548.782.9973162711.7344.96426N
335<*>Capricorni521115.673.3553174625.0050.331741S
336bEquulei6211257.712.9813181425.6244.72558N
337Aquarii6211314.773.2863181841.5349.291344S
338aCephei3211346.851.4273182642.6921.406145N
339bAquarii321211.123.1653201516.7447.48627S
340eCapricorni4212552.293.379321284.3450.682021S
341bCephei321261.180.8213213017.7612.326941N
342gCapricorni3 4212859.143.3293221447.1549.931733S
343kCapricorni5213127.983.3603225159.7450.401946S
344ePegasi3213421.532.9433233522.9944.15858N
345p1Cygni4213459.632.1163234454.3831.745017N
346dCapricorni3213558.683.3103235940.2549.65171S
347*præc. a Aquarii.21558.21. . .328473.15. . ....
348aAquarii3215529.753.0673285226.2546.00117S
349gAquarii3221118.893.0943324943.3946.41223S
350pAquarii4 522154.003.0653334559.9845.97022N
351zAquarii4221831.683.0793343755.2646.1812S
352sAquarii522202.993.186335044.8447.791142S
353Lacertæ422237.612.4313354654.1436.464916N
354hAquarii422254.593.079336168.7846.1919S
355kAquarii5222723.383.1173365050.6746.76514S
356zPegasi3223129.062.9813375215.8944.72948N
357hPegasi3223337.873.7923382427.9141.882911N
358t1Aquarii522374.703.1973391610.5747.96157S
359t2Aquarii5 6223859.293.1903394449.4147.851439S
360lAquarii4224210.523.1373403237.8747.05838S
|
Catalogue of the principal Fixed Stars for the Beginning of the Year 1800.
No. of Stars.Names and Characters of the Stars.Magni- tude.Right Ascens. in time.Annual Variat. in ditto.Right Ascens. in degrees, &c.Annual Variat. in ditto.Declination North and South.Annual Variat. in ditto.
    h.m.s. 1/100s. 1/1000°″ 1/100″ 1/100°  
       +   +     
361<*>Cephei4224235.332.1093403849.9531.63659N
362dAquarii322441.803.201341027.0648.021653S
363*præc. aPisc. aust..224017.35. . .340420.25. . ....
364Fomalhaut1224633 603.3303413824.0049.953041S
365*seq. a Pisc. aust..224838.04. . .342930.60. . ....
366bPegasi222545.502.8743433122.4743.11270N
367Markab2225447.992.9643434159.8544.46148N
368*seq. a Pegasi.225535.64. . .3435354.60. . ....
369fAquarii4 523357.393.1093455920.7946.6477S
370y2Aquarii523523.053.1253462045 6846.881010S
371gPiscium523646.423.0573464136.3745.85212N
372y3Aquarii323832.633.12534789.4846.881042S
373Piscium6232611.403.0653513250.9645.9710N
374lPiscium5233151.013.0663525745.0845.99040N
375Piscium5 6233610.883.062354243.1845.93223N
376wPiscium523492.883.0613571543.1645.92546N
377*præc. aAndrom..235545 47. . .3585622.05. . ....
378*præc. a Androm..235615.283.060359349.1945.90
379aAndromedæ223584.323.065359314.9545.972759N
380*seq. aAndrom..0132.98. . .02314.70. . ....
381bCassiopeiæ2 3235834.323.0513593834.7545.76583N
Another Catalogue of 162 Principal Stars, shewing their Mean Declinations to Beginning
of the Year 1800.
No.Stars Names.Mean Declin.Annual Va-No.Stars Names.Mean Declin.Annual Va-
north.riation.north.riation.
°°
1Polaris881425}+ 19.5711aLyræ383615}+ 2.59
2Polaris88142612aLyræ383610
3hUrsæ majoris50194- 18.2013zHerculis325819- 7.40
4aPersei49810+ 13.5914Castor321854}- 6.95
5<*>Ursæ majoris48499- 13.2115Castor321841
6dPersei47814+ 12.3516Pollux282947- 7.46
7Capella454650+ 5.0917bTauri282525}+ 4.08
8aCygni443420}+ 12.5218bTauri282530
9aCygni44341919eBootis275532- 15.59
10bBootis411111- 14.5420aAndromedæ275915+ 20.25
|
The Mean Declinations of 162 principal Stars for the Beginning of the Year 1800.
No.Stars Names.Mean Declin.Annual Va-No.Stars Names.Mean Declin.Annual Va-
north.riation.north.riation.
°°
21aAndromedæ275911+ 20.2566gGeminorum163328- 2.22
22bCygni273251+ 7.0467gSerpentis161940- 11.01
23Gemma272348}- 12.5068bSerpentis16321- 11.75
24Gemma27234969Aldebaran16543}+ 8.16
25mLeonis265637- 16.4670Aldebaran16545
26bPegasi265958+ 19.2171bLeonis154130}- 19.96
27eGeminorum251855}- 2.7272bLeonis154127
28eGeminorum25185673gDelphini152440+ 12.68
29dHerculis2554- 4.5674aDelphini151248+ 12.21
30eLeonis244117- 16.1075gTauri1581+ 9.42
31zLeonis242427- 17.5676zBootis143534- 15.85
32Alcione232834+ 11.8877aHerculis143738- 4.75
33Electra232827+ 12.0478aPegasi14749}+ 19.22
34Atlas232554+ 11.7479aPegasi14757
35Propus231540+ 0.7580gPegasi14416+ 20.04
36tPegasi223851+ 19.5781gPegasi14415+ 20.04
37mGeminorum223612- 0.8982bDelphini135431+ 12.05
38hGeminorum223259- 0.1983zAquilæ133432+ 4.83
39hGeminorum22335- 0.1984Regulus125623}- 17.24
40aArietis223037+ 17.5585Regulus125620
41aArietis223040+ 17.5586aCancri123730- 13.18
42dGeminorum222019- 5.8387aOphiuchi124255}- 3.05
43gCancri221043- 12.2888aOphiuchi12437
44mCancri2299- 9.6789eVirginis12211- 19.54
45bHerculis21562- 8.3890dSerpentis111256- 12.57
46dLeonis21371- 19.4391oLeonis104740- 15.94
47zTauri21032+ 3.0592eDelphini103750+ 11.73
48gLeonis205054- 17.7293<*>Leonis191952- 18.24
49zGeminorum20510}- 4.4894gAquilæ1086}+ 8.17
50zGeminorum2051595gAquilæ10810
51nGeminorum201934- 1.4496ePegasi85743+ 16.10
52Arcturus201345- 19.1097bCanis minoris84051- 6.51
53Arcturus201345* - 19.1098aAquilæ82058}+ 8.51
54gHerculis193752- 9.0599aAquilæ82048
55hBootis192419- 18.00100aOrionis72127+ 1.42
56dCancri185252- 12.40101aOrionis72127+ 1.42
57<*>Pegasi185714+ 14.91102eHydræ7837- 12.60
58bArietis184930+ 18.03103aSerpentis7355}- 11.94
59gArietis181829+ 18.09104aSerpentis7350
60dSagittæ18315+ 7.73105dHydræ62322- 11.97
61hLeonis174357- 17.18106bAquilæ5554+ 8.86
62aSagittæ173348+ 7.73107bAquilæ55519+ 8.86
63d1Tauri17338+ 9.19108Procyon54411- 7.51
64<*>Leonis163113- 19.43109bOphiuchi43941- 2.35
65gGeminorum163327- 2.22110dVirginis42913- 19.66
|
The Mean Declinations of 162 Principal Stars for the Beginning of the Year 1800.
No.Stars Names.Mean Declin.Annual Va-No.Stars Names.Mean Declin.Annual Va-
north.riation.south.riation.
°°
111<*>Serpentis35712+ 3.97156gEridani1453- 10.90
112aCeti31749}+ 14.70157aLibræ15120}+ 15.40
113aCeti3180158aLibræ15120
114bVirginis25335}- 19.97159dCorvi15245+ 19.98
115bVirginis25338160bCapricorni152410- 10.71
116gOphiuchi24742- 1.97161gCanis majoris15216+ 4.69
117dAquilæ24336+ 6.44162hOphiuchi152758+ 5.33
118gCeti22317+ 15.77163iAquarii154854- 17.14
119aPiscium14740+ 17.73164gCorvi162547+ 20.04
120hAntinoi03012+ 8.63165Sirius16277+ 4.43
121dOrionis02717- 3.38166Sirius16275+ 4.33
122zVirginis02548- 18.72167dAquarii165259- 18.85
South Decl.
123iHydræ0818- 15.86168dCapricorni17138- 16.19
124gVirginis0214+ 19.86169aCrateris171411+ 19.11
125dCeti03218- 15.97170iCapricorni173322- 15.82
126aAquarii1177}- 17.15171gCapricorni173958- 14.97
127aAquarii1177172bCanis majoris175155+ 1.18
128<*>Orionis12024- 3.02173aLeporis175822- 3.18
129<*>Antinoi12410- 10.05174<*>Capricorni1813- 13.81
130zOrionis2333- 2.60175<*>Scorpii185546+ 10.03
131gAquarii22331- 17.81176bCeti1959- 19.84
132dOphiuchi3108+ 9.77177bScorpii191446+ 10.52
133zSerpentis33932- 0.93178mSagittarii21550- 0.09
134eOphiuchi41137+ 9.47179pSagittarii211945- 4.95
135<*>Virginis4284+ 19.39180eCorvi213032+ 20.05
136bEridani52116- 5.41181dScorpii22230+ 10.92
137iOrionis630- 3.04182oSagittarii22121- 4.51
138bAquarii62637- 15.39183bCorvi221717+ 19.94
139fAquarii7725- 19.44184gLeporis223115- 2.11
140aHydræ74756+ 15.21185aCorvi233650+ 20.04
141aHydræ74753+ 15.21186gScorpii242910+ 14.67
142Rigel82635- 4.81187<*>Ophiuchi244717+ 4.43
143bLibræ83814+ 13.82188sScorpii2568+ 9.38
144lAquarii83829- 18.89189pScorpii253136+ 11.06
145aSpica10646+ 19.01190Antares255838+ 8.75
146Spicæ10645+ 19.01191Antares255823+ 8.75
147zOphiuchi1091+ 8.02192dCanis majoris26510+ 5.18
148dEridani10275- 11.99193eCanis majoris284229+ 4.38
149mCeti112248+ 15.71194zCanis majoris295850+ 1.07
150lVirginis122626+ 17.01195Fomalhaut304038- 19.01
151a1Capricorni13658}- 10.47       
152a1Capricorni1370       
153a2Capricorni13915}- 10.50       
154a2Capricorni13917       
155gLibræ14642+ 12.63       
|

Star

, in Electricity, denotes the appearance of the electric matter on a point into which it enters. Beccaria supposes that the Star is occasioned by the difficulty with which the electric fluid is extricated from the air, which is an electric substance. See Brush.

Star

, in Fortification, denotes a small fort, having 5 or more points, or saliant and re-entering angles, flanking one another, and their faces 90 or 100 feet long.

Star

, in Pyrotechny, a composition of combustible matters; which being borne, or thrown aloft into the air, exhibits the appearance of a real Star.—Stars are chiefly used as appendages to rockets, a number of them being usually inclosed in a conical cap, or cover, at the head of the rocket, and carried up with it to its utmost height, where the Stars, taking fire, are spread around, and exhibit an agreeable spectacle.

To make Stars.—Mix 3lbs of saltpetre, 11 ounces of sulphur, one of antimony, and 3 of gunpowder dust: or, 12 ounces of sulphur, 6 of saltpetre, 5 1/2 of gunpowder dust, 4 of olibanum, one of mastic, camphor, sublimate of mercury, and half an ounce of antimony and orpiment. Moisten the mass with gumwater, and make it into little balls, of the size of a chesnut; which dry either in the sun, or in the oven. These being set on fire in the air, will represent Stars.

Star-Board denotes the right hand side of a ship, when a person on board stands with the face looking forward towards the head or fore part of the ship. In contradistinction from Larboard, which denotes the left hand side of the ship in the same circumstances.— They say, Starboard the helm, or helm a Starboard, when the man at the helm should put the helm to the right hand side of the ship.

Falling Star, or Shooting Star, a luminous meteor darting rapidly through the air, and resembling a Star falling.—The explication of this phenomenon has puzzled all philosophers, till the modern discoveries in electricity have led to the most probable account of it. Signior Beccaria makes it pretty evident, that it is an electrical appearance, and recites the following fact in proof of it. About an hour after sunset, he and some friends that were with him, observed a falling Star directing its course towards them, and apparently growing larger and larger, but it disappeared not far from them; when it left their faces, hands, and clothes, with the earth, and all the neighbouring objects, suddenly illuminated with a diffused and lambent light, not attended with any noise at all. During their surprize at this appearance, a servant informed them that he had seen a light shine suddenly in the garden, and especially upon the streams which he was throwing to water it. All these appearances were evidently electrical; and Beccaria was confirmed in his conjecture, that electricity was the cause of them, by the quantity of electric matter which he had seen gradually advancing towards his kite, which had very much the appearance of a falling Star. Sometimes also he saw a kind of glory round the kite, which followed it when it changed its place, but left some light, for a small space of time, in the place it had quitted. Priestley's Elect. vol. 1, pa. 434, 8vo. See Ignis Fatuus.

Star-fort, or Redoubt, in Fortification. See Star, Redoubt, and Fort.

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ABCDEFGHKLMNOPQRSTU and VWXYZABCEGLMN

Entry taken from A Mathematical and Philosophical Dictionary, by Charles Hutton, 1796.

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SPOUT
SPRING
SQUARE
STADIUM
STAFF
* STAR
STARLINGS
STATICS
STATION
STATIONARY
STEAM