I variation in defect taking place when the quan- 
of. ' become ‘great. 3. And when shot of 
rent weights are employed, with the same quantity 
er, the velocities communicated to them are near- 
lyin ' subduplicate ratio of their weights, 
_ 4. So that, universally, shot which are of different 
wags, and impelled by the firing of different quantities 
: powder, acquire velocities which are directly as the 
square roots of the quantities of powder, and inversely 
as the square roots of the weights of the shot, nearly. 
5. It would therefore be a great improvement in attihe 
to make use of shot of a long form, or of heavier 
_ matter; for thus the momentum of a shot, when fired 
with the same weight of powder, would be increased in 
_ the ratio of the square root of the weight of the shot. 
6. It would also be an improvement to diminish the. 
win ; for by so doing, one third or more of the 
“quantity of powder might be saved. 7, When the im- 
provements mentioned in the last two articles are con-" 
sidered as both taking place, it is evident that about 
half the unter of powder might be saved, which is a 
very considerable object. But im t as this saving 
may he, it seems to be still exceeded by that of the 
article of the guns ; for thus a small gun may be made 
i have thee md execution of of two or three 
es its size in t nt mode, di ing a 
shot of two or three deica thes weight a its sone ‘ail 
_ orround shot: And thus a small ship might discharge 
shot as heavy as those of the greatest now made use of. 
“In the year 1781, Count Rumford instituted a series 
of experiments with musket barrels. The machinery 
__ which he used was ingeniously contrived and well ex- 
© ecuted, and his object was to determine the initial ve- 
locity of bullets, the recoil of the barrel, the effect of 
firing the charge in different parts of it, and the most 
advantageous situation for the vent. The following 
were the principal results which he obtained. He 
id that when the weights and dimensions of the 
bnilets are the same, their velocities, when discharged 
from the same piece, are in the subduplicate ratio of 
the weight of the charges; and he concludes, from 
numerous experiments, the vent may be placed in 
any part of the chamber’ where it will best answer on 
other accounts, Hence Count Rumford recommends 
that the bottom of the bore should be-of a hemispheri- 
eal form; 'that the vent should be brought directly 
through the side of the barrel in a line perpendicular 
to its axis, and) pointing to the centre of the hemi- 
spherical concavity of the:chamber. - . 
In these 0 fabintoes the ballistic pendulum of: Ro- 
bins was employed ; butin.co ence of a suggestion 
contained in Robins’s new principles of gunnery, Count 
Rumford pr , and: put in practice, anothér method 
of determining the velocities of bullets, by suspending 
____ the. gun in a horizontal position by two pendulous rods,. 
_and determining the velocity of its recoil from the arc 
__of its ascent, measured by a ribbon, as in the ballis- 
tic eg Te ' The velocity, of: the bullet | will. be 
= —— X W; where W is the weight of the gun, 
V the velocity of its recoil when fired without a bullet; 
the velocity of the recoil when the same charge im- 
els a bullet, B the weight of the bullet, and v its ve- 
} ci .. By comparing the results obtained in this way, 
_ with others obtained from the ballistic pendulum, Count 
Rumford found, that in several cases they agreed, but 
GUNNERY. 
part of 
567 
that in others the differences were so great, 
eter ren ought not in general to be relied upon. 
A v 
dertaken in tes 1783, under the direction of Ma- second’vet 
jor Bloomfield, and by the orders of the Duke of Rich- 5*P* 
mond, Master-General of the Ordnance. They were 4, 1791. 
carried on in the summers of 1783, 1784, 1785, 1787, 
1788, 1789, 1791, &c. principally with a view to the 
following objects : 
1, Todetermine the velocity of balls impelled by 
pe charges, from pieces of different lengths, but 
the same weight and calibre. 
“2. To determine their velocities with different chargesy 
when the weight and length of the gun are the same, 
3. To determine the greatest velocity due to diffe- 
rent lengths, by making the charge as great as the gun 
will bear. , 
4. To determine the effect of varying the weight of 
the gun, every thing else remaining the same. 
5. To determine the penetration of balls into blocks 
of wood. : : 
6. To determine the ranges and times of flight, and. 
the velocities of balls, by striking the ballistic pendu- 
lum at various distances, and to compare them’ with. 
their initial velocities, in order to ascertain the air’s. 
resistance. 
7. To determine on effect ~ wads ; = ae ey 
grees of ramming ; of different degrees of wiadage, an 
of different postitine of the vent; of chambers and: 
trunnions, and every other circumstance necessary to be 
known for the improvement of artillery... 
These experiments were carried on with great suc~ 
cess, excepting in the subject of ranges, which were 
less regular and uniform than could have been wished. 
The ballistic pendulum was from 600 to 800 pounds 
weight. The balls were generally one pound weight, 
and the powder was increased from: one ounce till, the- 
bore was quite full: : 
The following are the general results, as- givem by: 
Dr Hutton: 
History. 
that the 
extensive set of experiments was un- Dr Hutton’s 
of 
ts 
“1. That the velocity is directly as the square root General re- 
of the weight of powder, as far as to about the 
of eight ounces; and so it would continue. for all,ced by Dr 
charges, were'the' guns of an indefinite length. . But as: 
the length of the charge is increased; and: bearsa more 
considerable proportion to the length of the bore, the 
velocity falls the more short of that proportion. 
2. ‘That the velocity of the ball increases with the 
charge tova certain point, which-is liar to each gun 
where it is Seer ;-and that, by further increasing 
the charge, the velocity gradually diminishes till the. 
bere is quite full of powder: That this cliarge, for the 
greatest velocity, is greater as the gum is longer, but 
not , however, in so high a proportion as the 
length of the gun is; so that the part of the bore filled 
with: powder ai a less’ proportion to the whole)in 
the long guns than it does in the short ones; the. 
whole which is filled being indeed nearly; 
in the reciprocal subduplicate ratio of the length of the- 
empty part. And the other. circumstances are as im: 
this Table: 
Table of Charges producing the greatest’ Velocity. 
t en: Part of the, Weight of the 
Gun. ey ed aa Ww > Poeaer. 
Number Inches, Inches, Ounces, 
1 28.2 8.2 vr 12 
2 88.1 9.5 Yr 14 
3 57.4 10.7 as 16 
4 79.9 12.1 ts 18 
sults dedu- 
