186 OF PROJECTILES.

since the (hot in ascending, passes continually from a denseto a more rarified medium, while the reverse takes placewhen the shot descends.

CHAP. III.

Of the Effect? of Cannon Shot on Works.

173. r sH E use of heavy artillery (64) is to ruin anddemolish permanent fortifications and works.

In the attack of fortresses, 32 prs. are used for batteringin breach, when the ramparts are of great solidity ; but,from the great expence attending these heavy guns, and thedifficulty of transporting them, 16 prs. serve for dismount-ing the artillery in the outworks, and beating down the de-fences. For richochet and hot-shot firing, 4 and 8 prs. areused, as they require less ammunition, and fewer men towork them.

In the defenpe of places, against which the besieger canestablish any number of batteries he pleases, the proportionof 32 prs. Ihotild not exceed a third of the whole number ofguns in the garrison ; as'8 prs. v. ill serve for firing against theopening of the trenches, and 16 prs. against the approaches :but, if the situation of the ground be such, that the artilleryof the place has a decided superiority over any batteries thebesieger can erect ; then, to take full advantage of this cir-cumstance, the number of 32 prs. should be increased : long4 prs. will keep the enemy in respect around the place, anda few short light pieces (66) may be held in readiness formaking sallies.

174. To use fire-arms to the greatest advantage, theeffect of each shot should be observed: (141) for thispurpose;

1. The guns and carriages should be constructedwith the utmost accuracy.

2. The guns' should be served with care and judg-ment, and placed at a proper distance from the objectsintended to be battered.

175. In the former part of this treatise, the principles ofthe best construction for guns were fully explained : but, as anofficer is sometimes obliged to use guns defective in somematerial point, he ought to consider by what expedient he

can