THEORY OF THE MOTION OF ROCKETS. gy^ 



and complete system ; especially as their use is likely to 

 become greater, and the improvements in making them ex- 

 tended. 



The manner in which the military rocket is projected is Modeof their 

 from a case or long hollow barrel, fixed strongly to a frame Pi9J<=ction. 

 or carriage like the several pieces of cannon : the rocket being 

 first screwed to a lath or rod of fome inflexible substance, 

 to prevent any irregularity or perturbation of motion in it 

 during its flight; and the elevation of the machine, from 

 which it is thrown in any required case of devastation, 

 belongs, like that of artillery, to an experienced practi- 

 tioner. 



It is a matter of no consideration to the rocket engineer. Measure of 



to know the proportion of the sevewl ingredients, with ^l^^.'^"''^"^'^^'®^ 



1-11 i" • -111 - '^^^"' compo- 



which the rocket matter is made, provided the measure ot sition. 



the strength of the composition be given. Such important 



datum in this very interesting theory I have not at present 



been able, for want of experiments, to ascertain ; but it is 



presumed, that the force of the fluid generated from firing 



it cannot differ very much from that from fired gunpowder, 



which is about 1000 times as great, (according to Robins,) as 



the pressure of the atmosphere; and until I am able to 



convince myself otherwise, I shall adopt this as the measure 



of the strength of the rocket composition. 



Before entering upon the several computations respecting 

 the motion of rockets ; it will not perhaps be wholly ungra- 

 tifying to readers in general, to exhibit two or three of 

 these machines, and give some little description of them, 



AC D B (Plate VIII, fig. 3,) is the case of the rocket of The rockfti^ 

 cylindrical figure and made of sheet iron ; a the place dcscribi-i. 

 where the rocket is fired at the base of it A B ; and C GD 

 is the head of the rocket in the form of a right cone, and filled 

 with inflammable matter, that consumes much more,slovvly 

 than that with which the case or bod}' is filled. This head 

 is made also of sheet iron, and is quite solid near the apex G, 

 m order that it may the better enter any object of pene- 

 trable substance, as ships of war, and all buildings composed 

 of combustible and yielding materials. The white spots in 

 the head denote holes, through which the fire and flame 

 rush and fire the building into which the rocket penetrates. 



The 



