Sio 



NATURE 



[August 26, 1920 



and fired, most of the gases would escape from 

 the moon's attraction. The highest velocity gases 

 would without doubt (since 8000 ft. -sec. is only 

 the average velocity) ^^scape from Mars, if the 

 planet had no atmosphere. 



It should be remarked that, as shown by experi- 

 mental results, the best form of nozzle has not 

 yet been made, so that even 8000 ft.-sec. can be 

 exceeded by further research. 



(2) The heavy chamber, as mentioned above, 

 while permitting- high velocities of the ejected 

 gases to be obtained, would be an actual disad- 

 vantage if a single charge were to be fired. 



Fig. 3.— Chamber held in a support to test influence of air upon 

 the propulsion_of a rocket. 



because of the large weight. It is necessary, then, 

 that some means should be employed whereby 

 charges may he fed successively into the same 

 combustion chamber. If this is done it is evident 

 that most of the rocket can consist of propellant, 

 which is one of the conditions necessary for the 

 attainment of great altitudes. 



(3) When the magazine containing the charges 

 just mentioned is nearly empty, it is easily seen 

 that the propellant is no longer a large fraction 

 of the entire mass of the apparatus. Hence, in 

 order that the fraction shall remain large, it is 

 NO. 2652, VOL. 105] 



necessary that one or more rockets, really copies 

 in miniature of the larger primary rocket, should 

 be used if the most extreme altitudes are to be 

 reached, in order that the above fraction will, at 

 no time during the ascent, become small. 



Summary of Results to Date. 



The theoretical work, done at Princeton 

 University in 191 2, was not followed by experi- 

 mental tests until 191 5, at Clark University. The 

 work has since been continued at Clark Uni- 

 versity, in the magnetic laboratory at the 

 Worcester Polytechnic Institute, and at the 



Fic. 4.— Pipe into »v^ch chamber was fired ti> a tank exhausted to a low 

 pressure, the gases moving in a circular path until stjpped by friction. 



Mount Wilson Observatory in California— for the 

 greater part of the time under a grant from the 

 Smithsonian Institution. 



The results of this work have shown, first, that 

 most of the heat energy of even so powerful a 

 propellant as dense nitroglycerine smokeless 

 powder can be converted into kinetic energy of 

 the ejected gases. They have demonstrated, 

 secondly, that a multiple charge rocket can be 

 made which will fire several charges in succession, 

 is light and simple, and travels straight. 



In order to demonstrate whether or not the 

 rocket depended for propulsion upon the presence 



