, in Artillery, a shell, or hollow ball of castiron, having a large vent, by which it is filled with gun-powder, and which is fitted with a fuze or hollow plug to give fire by, when thrown out of a mortar, &c: about the time when the shell arrives at the intended place, the composition in the pipe of the fuze sets fire to the powder in the shell, which blows it all in pieces, to the great annoyance of the enemy, by killing the people, or firing the houses, &c. They are now commonly called shells simply, in the English artillery.

These shells, or bombs, are of various sizes, from that of 17 or 18 inches diameter downwards. The very large ones are not used by the English, that of 13 inches diameter being the highest size now employed by them; the weight, dimensions, and other circumstances of them, and the others downwards, are as in the following table.

Diameter of the Shell.Weight of the Shell.Powder to fill them.Powder to burst them into most pieces.
13 inch19594 1/278
1089414 1/234
 84623 1/220
 5 4/5 Royal14 1/211 1/2014
 4 3/5 Cohorn7 1/2007

Mr. Muller gives the following proportion for all shells. Dividing the diameter of the mortar into 30 equal parts, then the other dimensions, in 30ths of that diameter, will be thus:

Diameter of the bore, or mortar30
Diameter of the shell,29 1/2
Diameter of the hollow sphere21
Thickness of metal at the fuze hole3 1/2
Thickness at the opposite part5
Diameter of the fuze hole4
Weight of shell empty10/117d
Weight of powder to fill it2/473d
where d denotes the cube of the diameter of the bore in inches.—But shells have also lately been made with the metal all of the same thickness quite around.

In general, the windage, or difference between the diameter of the shell and mortar, is 1/60 of the latter; also the diameter of the hollow part of the shell is 7/10 of the same.

Bombs are thrown out of mortars, or howitzers; but they may also be thrown out of cannon; and a very small sort are thrown by the hand, which are called granados: and the Venetians at the siege of Candia, when the Turks had possessed themselves of the ditch used large bombs without any piece of ordnance, but barely rolled them down upon the enemy along a plank set aslope, with ledges on the sides to keep the bomb right forwards.

Mr. Blondel, in his Art de jetter des Bombes, says the first bombs were those thrown into the city of Watchtendonch in Guelderland, in 1588; and they are described by our countryman Lucar, in his book on Artillery published this same year 1588; though it is pretended by others that they were in use near a century before, namely at the siege of Naples in 1495. They only came into common use, however, in 1634, and then only in the Dutch and Spanish armies. It is said that one Malthus, an English engineer, was sent for from Holland by Lewis the 14th, who used them for him with much success, particularly at the siege of Cohoure in 1642.

The art of throwing bombs, or shells, forms a principal branch of Gunnery, founded on the theory of projectiles, and the quantities and laws of force of gunpowder. And the principal writers on this art are Mess. Blondel, Guisnée, De Ressons, De La Hire, &c.

Bomb-Chest, is a kind of chest usually filled with bombs, and sometimes only with gunpowder, placed under ground, to blow it up into the air with those who stand upon it; being set on fire by means of a saucissee fastened at one end. But they are now much out of use.

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

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BOFFRAND (Germain)