TllACT 37.

OF GUNNERY.

273

sponds 35° O' for the elevation in the 2d column, and thenumber 2 - 85l5 in the 3d column ; this multiplied by the al-titude 4430, gives 12632 feet, or almost miles for thegreatest range.

124. Tiiis however is much short of the distance which, itis said, the French have lately thrown some shells at the siegeof Cadiz , viz, 3 miles, or more, which it seems has been ef-fected by means of a peculiar piece of ordnance, and byloading or filling; the cavitv of the shell with lead, to renderit heavier, and thus make it btter to overcome the resistanceof the air. Let us then examine what will be the greatestrange of our 13 inch shell, if its usual cavity were quite filledwith lead, when discharged with the projectile velocity of2000 feet.

125. Now the diameter of the cavity, being about ofthat of the mortar 13, will be nearly 9 inches. And theweight of a globe of lead of this diameter is 139*3lb : whichadded to 187‘8, the weight of the shell empty, gives S27lb,the whole weight of the shell when the cavity is filled withlead, which was found 286 when supposed all of solid iron,their ratio or quotient is ’STSS. Then, as before, the theo-rem will be 178^/ - - " = 190 Vd for the terminal velocity;■which, when d—12'8, becomes 680 for the terminal veloci-ty; therefore its producing altitude is — =7225. Then, by

the same method as before, jryjy = 2‘941 ; which numberfound in the first column of the table of ranges, the oppositenumber in the 2d col. is 37°20 f for the elevation of the piece,and in the 3d column 2'216S, which multiplied by 7225,gives 1G005 feet, or 3 miles and 165 feet.

So that our 13 inch shells, discharged at an elevation ofabout 37 degrees, would range nearly the distance men-tioned by the French , when filled with lead, if they couldbe projected with so much as 2000 feet velocity, or upwards.This however it is thought cannot be effected by our mor-tars ; and that it is therefore probable the French , to giveVOL. III. T