OF GUN-METAL.

* 3 °

considerably stronger than that used formerly: the chargesthen being necessarily larger, occupied a greater space in thelength of the bore Cannon not to be injured by long firing,and to project their sliot with justness (9;, should be shorterthan the guns anciently were: but excess on this fide is to beequally guarded against, as on the other; for short guns oflarge calibre soon damage the embrasures ; the initial velocityof the shot, the length of range, and effects en the objectare diminished; and there is more probability of error inpointing short guns than long ones,

66. After the various opinions that have at different timesbeen suggested on the proper length of guns, intended tofire through embrasures, all nations seem to have adoptedWith little variation the following proportion :

Nature of Guns.

Pr.

32

16

8

4

Length of Bore.

Feet. Inches »

10 O

9 6

8 6

6 9

This is the common length: when longer they are termedlong , and when shorter, Jhort guns. (PI. 1, Fig. 2.) Set offon the line B F of a gun of any calibre three diameters ofthe bore, for the charging cylinder; divide the remainder CF into four equal parts at H, G, K, and make FL = FK :B L may be then considered as the greatest length that gunsshould be ever made of, to avoid the inconveniences pointedout in the preceding paragraph: and if from B F, K F betaken, the remainder B K is the least length for guns withcylindric bores.

67. When 32, 16, 8 and 4 prs. (66) are loaded withthe usual service charges of powder and rammed with equalforce, the initial velocities will in short ranges increasein proportion as the calibres diminish; but in long ranges,the shot from tue resistance of the air will be projected fartherfrom guns of large than of small calibre, in proportion tothe distance; as appears by the following experiments. Theguns were loaded as above directed, and the shot severallyfell on three spots below the plane of the battery.

Number