448 transactions of the american institute. 



Gunpowder as a Motor. 



Ml'. Ewbaiik, late Commissioner of Patents, communicates to the Frank- 

 lin Journal his objections to compressed air and gunpowder as traveling' 

 forces. His remarks on gunpowder deserve especial attention. After 

 noticing the conflicting statements of tlie amount of force generated, he 

 says : 



To whatever cause the discrepancies are to be ascribed, to variations in 

 the quantities of the powder, its filling or only partly filling the exploding 

 chamber, &c., there is enough in all conscience in the lowest estiniates to 

 lead mechanicians to inquire if this amazing agent, resistless as an ex- 

 ploding force, may not be converted into a quiet and efiicient working one'. 

 Hautefille, Huygens, and Papin attempted this in the seventeenth century, 

 and many more in the succeeding and the present one. Numerous notices 

 may be found in the Mechanical Journals, but I do not remember any par- 

 ticular description of the testing apparatus,- or any definite item of results. 

 Desirous of ascertaining if the force could be introduced as a substitute for 

 animals in rail cars at a moderate cost, I consulted my friend, Mr. James 

 Bogardus, whose mechanical knowledge and inventive resource have rarely 

 if ever been surpassed. The apparatus adopted was designed by him. It 

 is only necessary to refer to a part of it here. 



Instead of receiving the explosive impulse on air, the most elastic and 

 durably elastic of ageiits, as suggested in the Patent Office Report of ISiQ, 

 the piston driven by the powder conlpressed a steel spring formed by bend- 

 ing to and fro, a bar, twenty feet long, two inches wide, and one-quarter 

 of an inch thick, into a series of short turns. The compressing force was 

 determined directly by a weight passing over a pulley and making addi- 

 tions to it as the compression proceeded along a finely graduated scale. 

 There could, therefore, be little or no mistake made in the amount of force 

 thus received and given out to the revolving mechanism. The cylinder, 

 or gun, was two inches bore and sixteen and a half inches long. The pis- 

 ton and rod were of one piece of metal, the latter one .and a half inches 

 square. 



The experiments were interrupted by the death of ifr. Pornbach, killed 

 while packing a case of gun cotton. "VVe had tried ivhile powder and pre- 

 ferring it, were waiting a further supply from him. The delay in resuming 

 them is moreover due to the fact that the magic power ascribed to powder 

 in the books, and mining and military engineering, vanishes in the work- 

 shop. 



The power of a single horse is commonly estimated at 33,000 lbs. raised 

 one foot per minute. 



We found ten grains of powder only raised 250 lbs. one foot, hence 132 

 such charges, or 1,320 grains, were required to bring it up to horse power. 

 A pound contains 7,000, and they could hardly keep the engine going five 

 and one-third minutes. Eleven pounds and a half would be consumed in an 

 hour, and that at twenty cents per pound would amount to over §22 for a 

 working day of ten hours. 



It should however be understood that from the construction of the testing 

 macliiu!?, a feeding channel and a small receptacle for the residuum were 



