TRACT 34.

IN GUNNERY.

13

75. Thursday, September 9, 1784.

Since the last experiments, the steadying-rods qf the gun-frame having been lengthened, and the pendulum block re-paired with a new core, Sec, we attended to weigh and mea-sure the several parts; the circumstances of which were asfollow :

Weight of the pendulum - 638 =: p

Therf. to its centre of gravity 75'93 gAnd its vibrations per minute 40 , 30 ;= n

The new stay-rods of the gun-frame weigh 17lb more thanthe old ones, so that now

lb

The weight of iron in the frame is 205Weight of gun and iron together 495Weight of gun,-iron, and leads - 934 = G

By this additional 17 lb weight of iron,' the values of gand n, or the centre of gravity and number of oscillations,will be altered ; which will cause an alteration in our theo-rem v — -X X by which the velocity of the ball is

96 bin 7 J J

determined from the recoil of the gun, in Art. 36. Thevalues of these two letters were, at Art. 42 and 43, foundto be g = 80‘47, and n =: 400 for the gun n* 2; but theformer will now become something less, and the latter some-thing greater.

Now the old and new iron stay-rods were nearly of equalthickness. But the old rods extended only 29 inches, andthe new ones 58 inches below the axis ; the difference is 29 ;and the half difference, or 14£ added to the old length 29,gives 43 a inches below the axis, where the middle or centreof gravity of the additional length is situated, the weight ofwhich part is 17 lb. But the centre of gravity was found tobe 80'47 below the axis, when the whole weight was 917 lb.Here, the difference of the two distances, or the distancebetween the two weights 17 and 917, being 37 inches, and