PROCEEDINGS OP THE POLYTECHNIC ASSOCIATION, 635 



into my -wagon, and suddenly dash me upon the pavement; the 

 said body being entirely unaware of having done any mischief. 

 This topic seems to open our way to a larger discussion of the 

 general question of social or legal restraint on the mischievous 

 uses of poisons. The recent disclosures by the German chemists 

 is fixing the attention of legislators again on this topic ; and we 

 may expect a much wider discussion of this matter in scientific 

 circles. 



COMPRESSED AIR AS A MOTIVE POWER. 



• Mr. Wm. L. Haskins read the following paper : 



On a former occasion I had the honor of introducing to this 

 society the subject of compressed air, as a motive power for the 

 propulsion of cars on railways. 



The consideration of objections to the proposed application of 

 the power, made here on the occasion referred to, and, if I suc- 

 ceed in removing them, a few suggestions as to some of the promi- 

 nent advantages of the system ; a system, I shall maintain, which 

 ofi"ers the most decided improvement over all other known meth- 

 ods of propulsion, will form the subject of the remarks I design 

 to offer on the present occasion. 



The public mind is ever averse to innovation upon established 

 customs in every department of mechanical science, more espe- 

 cially where a large investiture of capital has been devoted to 

 their establishment. So that, in the promulgation of new theo- 

 ries, however specious, their advocacy has to combat a world of 

 educational prejudice. 



" The analysis of the data of experiments and calculations, fairly 

 made thereon, with a practical knowledge of compressed air engi- 

 neering, will give the best prima facie evidence of the economy to 

 be effected by the use of this harmless (and beautiful) power." 

 And here I am quoting the very words employed, partly, by Mr. 

 Arthur Parsey, a distinguished civil engineer of England, in con- 

 nection with experiments made by himself, published in the leading 

 scientific mechanical journals of that country, and partly by the 

 Baron Von Rathen (of London) who made similar experiments.* 



In what follows, I shall have occasion to refer to and to quote 

 still further from these high authorities because the points to 

 which I propose to invite your attention are treated by them in 

 a manner, with a degree of force and perspicuity, which tran- 



• 1853, Practical Mechanic's Journal, 1348. 



