GUNNERY. 
termined, from the vibration of the pendulum after the ftroke, 
is on this principle of Rechakics that if a body in 
motion ftrikes on another at reft, and they are not ee 
ba the ftroke, but moye on with one common motion, 
then that common motion the motion with 
body before the 
On this principle it follows, 
at the agen of a bullet may be eg aa ina ge: y give en 
o them. See New Princ ip. of ey: p- a: 
29) fe. * See “6 the Phil. Tranf. N° 469. p. 444. where 
relating to anumber in Mr. Robins’ s Sth 
maps is mentioned or Math. Tae vol. i. p. 83, &c. 
D1 “proportion between the lengths of ribbon 
draw out at ‘different times, will be the fame with that of 
the velocities of the i impinging bullet 
» Now from the computations delivered by Mr. Robins, it 
appears, that the Lares of a bullet, whofe weight was 
it apo was 1641 
chord of the arch ace hed by the afcent of the eae 
fr in confequence of the blow, was 17! inches, here- 
3 the proportion of any other Jengths of ribbon drawn 
any percuffion, to 17%, the proportion of the velo- 
cy pee which the bullets i SAPIOg Gs to the known ees 
“he feet in 1", will be determined. 
s experiments of this kir ue are often attended with dan- 
get and difficulty, thofe who may be difpofed to make any, 
Ti tnd feveral as practical cautions, in p. 31s 3 sa 
33, of the faid trea 
Mr. 'T tompfon | resse Rumford) has made many experi- 
3 for determini ng the se ectics i bullets by means of a 
to the method of Mr. Robins; for 
_ fee Phil. Tranf. for ee » vol. seed 
ove de- 
he as machine 
cae is genes by ae ok the two fol- 
erent quantities of powder, 
from fix baa cae to this irty-fix, have a remarkable co- 
incidence, and fuch as occurs but in a few phiatophicd! 
fubjects : fo complicated a nature. 
Suppoling, for inftance, the length of a barrel to be 45 
inches, the quantity of powder 12 penny- he a 
containing it 25 inches, and the ball "3 
placed in the fame fituation in the fame piece, and was im- 
pelled by the fame quantity of powder, the Seager of fuch. 
an iron bullet would be greater than that of the leaden Nn oney, 
in the fubduplicate ratio of the {pecific gravities of lead and: 
iron ; and appenne that ratio to be as 3 to 2, and comput 
ing on the foregoing ——o it will appear, ~ an irom 
bullet of a weight; fh iece of ten eng 
with 16). eipapeies — a ag the expofon a ve~ 
tinued word carry it 
this proportion does not 
scare is not confiderable eno 
great v on from the tloctes 
thefe pa gin a 
more than is jut wcatiary for th 
3 whereas in real ice, eit. 
or ‘unikilfulnefs, it often Bappsnes. shat the Pi oy 
the tate fo much ex ‘diameter of the bullet, ‘tes. 
t part 
loving fo os fin steed Sell tees ee, eae. 
rie. Y= 5-0727 cs x ey o =614.58 the ‘elocia of the fhot may, in tee: be contiderably 
pt +5 s than what is here i ; Domes pak of this may 
te x. ‘birn ——? the ees where w denotes the velocity of ibly be compenfated by the greater heat which in all pro- 
: hen i Price Ue icaddins “ove et ie bability attends the firing’ thefe | ange quantities of mere 
ight of ‘he ball, > ke si Cane The theory here e _— uppoles what = recs 
vibration to theraduss, ¢ the Qi Oe ee Piast sa ation 
ce 0 oe ae & ame >< equally hot with iron. at ginning of. its white heat’, 
vity, o the dif- 
ecto © centre of: ‘ofeillation, ithe = nce ts the point 
of ofcillati rfor ey A 
4tCr VICMIALIO! secon alt ly 
min ute, when made : + epcllase in fmall. 
of thefe two: theorems is much the mo 
it is free from radicals, and becaufe th 
the number 
to make, - 
ey ae 
4/0 in the former, is to be firt computed agion of the powder, i 
ber of ofcillations which the and this, as has been faid, is confirmed 
but in very fmall quantities of powder 
lefs, and confequently the elaiticity lets than: what. ari 
fror this: f tion. Now this. elafh ity in. 
tities of powder has been fauna 4 in og bp 
lace... For inflance,, ac 
