FOUNTAIN
, in Philosophy, a spring or source of water rising out of the Ground. See Spring.
Fountain, or Artificial Fountain, in Hydraulics, a machine or contrivance by which water is violently spouted or darted up; called also a Jet d'eau.
There are various kinds of Artificial Fountains, but all formed by a pressure of one sort or another upon the water &c, viz, either the pressure or weight of a head of water, or the pressure arising from the spring and elasticity of the air, &c. When these are formed by the pressure of a head of water, or any other fluid of the same kind with the Fountain, or jet, then will this spout up nearly to the same height as that head, abating only a little for the resistance of the air, with that of the adjutage &c, in the fluid's rushing through; but, when the Fountain is produced by any other force than the pressure of a column of the same fluid with itself, it will rise to such a height as may be nearly equal to the altitude of a column of the same fluid whose pressure is equal to the given force that produces the fountain.
To Construct an Artificial Fountain, playing by the pressure of the water. This is to be effected by making a close connection between a head or elevated piece of water, and the lower place, where the Fountain is to play; which may be done in this manner: Having a head of water, naturally, or, for want of such, make an artificial one, raising the water by pumps, or other machinery: from this head convey the water in close pipes, in any direction, down to the place where the Fountain is to play; and there let it issue through an adjutage, or small hole, turned upwards, by which means it will spout up nearly as high as the head of the water comes from, as above mentioned.
To Construct an Artisicial Fountain, playing by the spring or elasticity of the air. A vessel proper for a reservoir, as AB, fig. 4, plate viii, is provided either of metal, or glass, or the like, ending in a small neck c, at the top: through this neck is put a tube cd, till the lower end come near the bottom of the vessel, this being about half full of water. The neck is so contrived, as that a syringe, or condensing pipe, may be screwed upon the tube; by means of which a large quantity of air may be intruded through the tube into the water, out of which it will disengage itself, and emerge into the vacant part of the vessel, and lie over the surface of the water CD.
Now, the water in the vessel being thus pressed by the air, which is, for ex. double the density of the external air; and the elastic force of air being proportional to its density, or to its gravitating force, the effect will be the same, as if the weight of the column of air, over the surface of the water, were double that of the column pressing in the tube; so that the water must be forced to spout up through, when the syringe is removed, with a force equal to the excess of pressure of the included air, above that of the external, that is, in this instance, with a force equal to the pressure of an entire column of the atmosphere; which being equal to the pressure of a column of 33 or 34 feet of water, it follows that the Fountain will play to nearly 33 or 34 feet high.
These aereal or aquatic Fountains may be applied in different ways, so as to exhibit various appearances; and from these alone arises the greatest part of our artificial water-works: even the engine for extinguishing fire, is a Fountain playing by the force of confined air.
A Fountain spouting the water in various directions. Suppose AB the vertical tube, or spout, in which the water rises, (fig. 5, pl. viii): into this let several other tubes be sitted; some horizontal, others oblique, or inclining, or reclining, &c, as at E, H, L, N, P, &c. Then, as all water retains the direction of the aperture through which it comes, that issuing through A will rise perpendicularly; and the rest will tend different ways, describing arches of different magnitudes.
Or thus: Suppose the vertical tube AB (fig. 6) through which the water rises, to be stopped at the| top, as in A; and, instead of pipes or cocks, let it be only perforated with little holes all around or only half round its surface: then will the water spin out, in all directions, through the little holes, to different distances.
And hence, if the tube AB be about the height of a man, and having a turn-cock at C; upon opening this cock, the spectators will be sprinkled unexpectedly with a shower.
Fountain playing by drawing the breath. Suppose AB (fig. 8, plate vi), a globe of glass, or metal, in which is fitted a tube CD, having a small orifice in C, and reaching almost to D, the bottom of the globe. Then if the air be sucked, or drawn with the mouth, out of the tube CD, and the orifice C be immediately immerged under cold water, the water will ascend through the tube into the sphere. Thus proceeding, by repeated exsuctions, till the vessel be above half full of water; then applying the mouth to C, and blowing air into the tube, upon removing the mouth, the water will spout forth.
Or, if the globe be put into hot water, the air being thus rarefied, will make the water spout as before.
And this kind of Fountain is called Pila Heronis, or Hero's Ball, from the name of its inventor.
Fountain, whose stream raises and plays a brass ball. Provide a hollow brass ball A (fig. 9, pl. vi), made very thin, that its weight may not be too great for the force of the water; and let the tube BC, through which the water rises, be exactly perpendicular to the horizon. Then the ball, being laid in the bottom of the cup or bason B, will be taken up in the stream, and sustained at a considerable height, playing a little up and down.
Fountain which spouts water in form of a shower. To the tube in which the water is to rise, fit a spherical, or lenticular head AB (fig. 1, pl. xi) made of a plate of metal, and perforated at the top with a great number of little holes. The water rising violently towards AB, will be there divided into innumerable little threads, and afterwards broken, and dispersed into the finest drops.
Fountain which spreads the water in form of a tablecloth. To the tube AB (fig. 2, pl. xi) solder two spherical segments, C and D, almost touching each other, with a screw E, to contract or amplify the interstice or chink, at pleasure. Some choose to make a smooth and even cleft, in a spherical or lenticular head, fitted upon the tube. The water spouting through this chink or cleft will expand itself like a cloth.—And thus, the fountain may be made to spout out in the figure of men, or other animals.
Fountain, which, when it has done spouting, may be turned like an hour-glass. Provide two glasses, A and B, (fig. 3, pl. xi) to be so much the larger as the fountain is to play the longer, and placed at so much the greater distance from each other as the water is desired to spout the higher. Let CDE be a crooked tube, furnished in E with a jet; and GHI another bent tube, furnished with a jet in I: GF and KL are to be other lesser tubes, open at both ends, and reaching near the bottom of the vessels A and B, to which the tubes CD and GH are likewise to reach.
Now if the vessel A be filled with water, it will descend through the tube CD; and it will spout up through the jet E, by the pressure of the column of water CD. But unless the pipe GF were open at G, to let the air run up to F, and press at the top of the surface of the water in the cavity A, the water could not run down and spout at E. After its fall again, it will sink through the little tube KL, into the vessel B, and expel the air through the tube GI. At length, when all the water is emptied out of the vessel A, by turning the machine upside down, the vessel B will be the reservoir, and make the water spout up through the jet I, the pipe KL supplying B with air to let the water descend in the direction GHI.
Hence, if the vessels A and B contain just as much water as will be spouted up in an hour's time, we shall have a spouting clipsydra, or water-clock; which may be graduated or divided into quarters, minutes, &c.
Fountain of Command. This depends on the same principles with those of the former: CAE (fig. 4, pl. xi) is a vessel of water secured against the entrance of the air, except through the pipe GF, when the cock C, by which it is filled, is shut. There is another pipe EDHB, going from the bottom of the water to the jet B in the bason DB; but this is stopped by the cock H. At the lowest part of the bason DB, there is a small hole at I, to let the water of the bason DB run into the bason GH under it; there is also a small triangular hole or notch, in the bottom of the pipe FG, at G. Turn the cock H, and the fountain will play for some time, then stop, then play again alternately for several times together. When those times of playing and stopping are known before hand, you may command the Fountain to play or stop; whence its name. The cause of this phenomenon is as follows: the water coming down the pipe EDHB, would not come out at B, if the air Ss, above the water, were not supplied as it dilated: now it is supplied by the pipe GF, which takes it in at the notch G, and delivers it out at F; but after some time the water, which was spouted out at B, falling down into the bason DB, rises high enough to come above the notch G, which stops the passage of the air; so that the air Ss, above the water in the vessel CAE, wanting a supply, cannot sufficiently press, and the Fountain ceases playing: But when the water of DB has run down into the lower bason GH, through the hole I, till it falls below the top of the notch G, the air runs up into the upper receptacle, and supplies that at Ss, and the Fountain plays again. This is seen a little before hand, by a skin of water on the notch G, before the air finds a passage, and then you may command the Fountain to play. It is evident that the hole I must be less than the hole of the jet, or else all the water would run out into the lower bason, without rising high enough to stop the notch G.
Fountain that begins to play upon the lighting of candles, and ceases as they go out. Provide two cylindrical vessels, AB and CD, (fig. 7, pl. xi.) connect them by tubes, open at both ends, KL, BE, &c, so that the air may descend out of the higher into the lower:| to the tubes solder candlesticks, H, &c, and to the hollow cover of the lower vessel CE, fit a little tube or jet, FG, furnished with a cock G, and reaching almost to the bottom of the vessel. In G let there be an aperture, furnished with a screw, by which water may be poured into CD. Then, upon lighting the candles H, &c, the air in the contiguous tubes becoming rarefied by the heat, the water will begin to spout through GF.
By the same contrivance may a statue be made to shed tears upon the presence of the sun, or on the lighting of a candle, &c: all that is here required, being only to lay tubes from the cavity where the air is raresied, to some other cavities placed near the eyes, full of water.
A Fountain by the Rarefaction of the air, may be made in the following manner: Let AB and CD, fig. 5, pl. xi, be two pipes fixed to a brass head C, made to screw into a glass vessel E, which having a little water in it, is inverted till the pipes are screwed on; then reverting it suddenly, so as to put A, the lower end of the spouting pipe AB, into a jar of water A, and the lower end of the descending pipe CD, into a receiving vessel D, the water will spout up from the jar A into the tall glass vessel E, from which it will go down at the mouth C, through CD, into the vessel D, till the water is wholly emptied out of A, making a Fountain in E, into D. The reason of the play of the Fountain is this: the pipe CD, being 2 feet 9 inches long, lets down a column of water, which rarefies the air 1-12th part in the vessel E, where it presses against the water spouting at B with 1-12th of the force by which the water is pushed up at the hole A, by the pressure of the common air on the water in the vessel A; so that the water spouts up into E, when the air is rarefied 1-12th, with the difference of the pressure of the atmosphere, and the forementioned rarefied air; i. e. of 33 to 2 3/4, or of 12 to 1. This would raise the water 2 feet 9 inches; but the length of the pipe A, of 9 inches, being deducted, the jet will only rise 2 feet. This, says Desaguliers, may be called a syphon Fountain, where AB is the driving leg, and CD the issuing leg.
Fountain of Hero of Alexandria, so called, because it was contrived by him. In the second Fountain above described, the air is compressed by a syringe; in this, (see fig. 6, pl. xi) the air, being only compressed by the concealed fall of water, makes a jet, which, after some continuance, is considered by the ignorant as a perpetual motion; because they imagine that the same water which fell from the jet rises again. The boxes CE and DYX, being close, we see only the bason ABW, with a hole at W, into which the water spouting at B falls; but that water does not come up again; for it runs down through the pipe WX into the box DYX, from whence it drives out the air, through the ascending pipe YZ, into the cavity of the box CE, where, pressing upon the water that is in it, it forces it out through the spouting pipe OB, as long as there is any water in CE; so that this whole play is only whilst the water contained in CE, having spouted out, falls down through the pipe WX, or of the boxes CE and DY above one another: the height of the water, measured from the bason ABW to the surface of the water in the lower box DYX, is always equal to the height measured from the top of the jet to the surfac<*> of the water in the middle cavity at CE. Now, since the surface CE is always falling, and the water in DY always rising, the height of the jet must continually decrease, till it is shorter by the depth of the cavity CE, which is emptying, added to the depth of the cavity DY, which is always filling; and when the jet is fallen so low, it immediately ceases. The air is represented by the points in this figure.
To prepare this Fountain for playing, which should be done unobserved, pour in water at W, till the cavity DXY is filled; then invert the Fountain, and the water will run from the cavity DXY into the cavity CE, which may be known to be full, when the water runs out at B held down. Set the Fountain up again, and, to make it play, pour in about a pint of water into the bason ABW; and as soon as it has filled the pipe WX it will begin to play, and continue as long as there is any water in CE. You may then pour back the water left in the bason ABW, into any vessel, and invert the Fountain, which, being set upright again, will be made to play, by putting back the water poured out into ABW; and so on as often as you please.
Spouting Fountain, or Jet d'Eau, is any Fountain whose water is darted forth impetuously through jets, or ajutages, and returns in form of rains, nets, folds, or the like.
Fountain-Pen, is a pen contrived to contain a quantity of ink, and let it flow very gently, so as to supply the writer a long time without the necessity of taking fresh ink.
The Fountain-pen, represented fig. 8, pl. xi, consists of divers pieces of metal, F, G, H, the middle piece F carrying the pen, which is screwed into the inside of a little pipe; and this again is soldered into another pipe of the same size as the lid G; in which lid is soldered a male screw, for screwing on the cover; as also for stopping a little hole at the place, and hindering the ink from passing through it: at the other end of the piece F is a little pipe, on the outside of which may be screwed the top cover H. A porte-craion goes in the cover, to be screwed into the last mentioned pipe, to stop the end of the pipe into which the ink is to be poured by a funnel.
To use the Pen, the cover G must be taken off, and the pen a little shaken, to make the ink run more freely.
