GUNNERY 
fion inthe motion. of ‘a ball at fome given, diftance from, the 
Piers e Ligh he exprefsly Pate that ‘¢ among. thefe projectiles 
which we make ufe. of, if they are of a heayy matter and 
noon Fal nay, if they < are. a a lighter matter, and have 
a cylindrical form, fuch as arrows, fhot from bows, their 
ek or, path will not_fenfibly. Secline from the curve of a 
para ola;” (See: his fourth Dialogue on Motion.) In this 
theory his fucceffors for a confider able time acquiefced, with- 
out trying how far the real motions of projectiles deviated 
from a parabolic — or plat WhRPSS the peiviange 
air Was, OF. sia nece o be atten 
erminations oft unnery. 
oP aeaR arife lg the refiftance of the air, in the fight 
of balls, chiefly on account of the extreme rarity of the air 
with the denfe and ponderous compofition of thofe 
=: bodies. they eftablifhed it as a kind d of genery! 
+ a in whic 
= = p 
of aeibing the Soeages: of their ted from the parabolic - 
curve to. the refiftance of. the ar. ed-an hypothefis 
ine ; e d{up- 
~ fame - all elevations 5 ; 1% by affigning a PASEO: magni- 
ose theory to 
Timents. 
“In the year 1683, Monf. Blondel "ame at Paris, a 
entitled « L’Art de jetter des Bombes,”’ in which 
air is fo very inc 
account in pbhice, 
both in France: and England, that there feem to have been 
Tone who fafpeced i its fallacy. 
Dr. Halley, ina paper communicated to the Royal So- 
i in 1686, exprefsly afferts, that in hele fhot_ of 
tim to 
wher refs thereon, ofition (occafioned 
ae afthe air to he ore! canno n-balls) is 
fearee ifcernible :'? and frem actual expe He oy infers, 
sr ogi in fmall and Lobe thot the the Tee of the 
muft be accounted for, yet in fhooting of 
ighty hombs,. there need be very little or no 
_ Rhil, 
‘as that of Dr. Halley, 
BRET he atin 
2 Phil. Nat,’”. 
uM, differe dios 
Rs a the curve prs Pare 3 ed Ieary 
oL 
‘Aduattne that no phe Ya- 
rs 
This opinion was fo generally received 
ir, that this-elaft 
e condenfed phate and being 
ewton, who, in 3687 publifhed his « Prinei. 
hematic she has demon: _ The 
+ -) that the curve mdcleched bya projectile, i in 
it ~ medi sh from a p goer 
bodies and a parabola far from Being. infenfible, wie there. 
fore, too confiderable to be ne The truth of thefe 
Spaclations ae Paget eftabli ay Pa . Huygens, i in his. 
-“ Difco ela Pefanteur,” Leide 
which wa "Ae riments and mathematical invefti- 
ob all projectiles was very different 
rabols 
99, in 
to, eftablith an y folid 
foundation upon them On ° agin tee occurs in which 
- Bernouilli applies the qotiaae of fir Ifaac Newton to 
the motions of projectiles. Cem. Acad. Petrop. tom. ii. 
r_ been, a 
+ 339 
Tn this es of error and aoa ca contradi€tion be- 
tween theory, and practice did the fcienc 
till the ingenious Mr. Robins, in the vee 1742, publifhed 
a {mall treatife, sabirien “6 eae. Principles of Gunrery,’? 
ries relating to the force of 
fion,. Fi oie of the refifting power of the air to fwift 
and flow motions, the deviation of the flight of projected 
_bodies from the parabolic curve in a degree never difcover 
or fufpeéted by any, and the deflection of bullets and other 
projectiles from the vertical plane in secalge the fhot is 
refulting from a rotatory motion which they accidentally ac- 
quire about.an axis. Thefe difcoveries "i e been confirmed 
felf i ule fpbleguent publistiony, 
and bj 
of Berlin, who pub litled 
and sf el ge 
Mr. Robins, from the related i in his “ Ree 
Principles of Gunnery Mes tas ee eaeclued. tad t the Bg 
fity of the common air, that the slafticty, of. this ff Age 
like that of the air, is proportionable to its denfity, inferred 
ic fluid, exifting in the powder in an extremely 
ANY extricated from the por 4 
der by combuttion, mt with an aftonifhing 
and. Salers pee the bullet or whatever elfe oppoted fe 
ii ae: 
fico-Mechanical Experiments,” p . 31. see Gu 
Mr. Robins, having thus ected the force of the 
powder, as the inteniity of the agent by w ‘hich the ‘projecs. 
tile i i to e urged, will pro- 
duce, or the “velocity with which it will impel a thot of a 
en ht from a-piece of ordnance. of ven dimenfions. 
ee ee he pro are folution the fo! owing pro > 
e dimen: Aas 2 ; ar angel Pos ets oe 
ball, and_ th ge ity.of its ch in ; ‘in 
cage loc hich, ball w ger pee | ra ae the explo 
fion, fup) ofing the elafticity or, pee PEELE, 2 
firft inftaut of hs sing tb gen, * Pies 
