THEORY OF THE MOTION OF ROCKETS. 245 



possible; and the angle, the sine of which is /, 30 degrees; 

 then /' =: • 5 or 4- (to rad,. 1); and taking the specific gravity 

 ofairat a medium, or S n 1 f , R will be found zz -0002343 

 ounces; which is the absolute resistance the rocket suffer* 

 when moving with a velocity of 1 foot per second. Hence 

 the expression above for v will become ------- 



4 rt^^c? (-0002343*71^) — ?-.{*0002S A3 sne) 



1 c — i — e A 



vtW c f 



). /(am) — (a TO — >ac) \ 



v-ooc 



0002343/ 



±l.li (-0002343 sne)' tl^^ (-0002343 sne)^ 



c c 



(a m) ■\- (am — ac) 



and substituting the values for a, c, d, &c., which are as fol« 

 low : namely, 



s = 1000 



n =z 230 ozs. 



w zi 18 lbs. = 288 ozs. 



c =: 10 lbs. zz l60 ozs. 



m = w -{* c zz 448 ozs. 



a. zz 3 sec. 



-- ' g = 16 ft. 



it IS V zr 



e = *7854 

 6941-575 ( 1344 — 864 



/ 1-95171 1-95171 



1-95171 1-95171 



1344 + 864 



^mi^^pi^ = 2820-3a5feet: which is th'ere- 

 1814180 



fore the greatest velocity the rocket can acquire, and which Velocity. 



it does acquire at the end of its burning. 



It is somewhat remarkable, that the whole resistance of 



the air to the rocket, on the supposition that gravity does 



not act, should so nearly approximate to the effect of this 



force (considered as constant) when there is no consideration 



of any resistance from the former ; the deviation causing no 



more than (2896-9895 — 2820-325 = ) 76*6645 feet per 



second 



