506 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



armor, was continued by several members ; the current of opinion being 

 rather against its feasibility, 



" The Burstiug- of Guns," was the subject selected for the next discus- 

 sion. Adjourned. 



'•} 



American Institute Polytechnic Association, 

 November VMh, 18G3. 



, Chairman, S. D. Tillman, Esq.; Secretary, Mr. B. Garvey. 



New. Steam Slide Valve. 



Mr. T. Tleenstjerner exhibited a model of his improved steam slide valve. 



Mr. B. Garvey. — The object of this invention is to relieve the valve as 

 much as possible of the pressure of the steam upon it, and also to avoid 

 the waste of steam which occurs in long steam passages, by reducing them 

 to a very short length; just suflScient to provide a clearance for the piston 

 "Within the cylinder. To accomplish these results, steam is admitted under 

 the interior of the valve through a steam belt running round the cylinder; 

 the steam then enters the ports, which are just so much shorter than the 

 same ports on the valve seat as the travel of the valve. The steara 

 exhausts at the ends of the valve into the steam-chest. In order to keep 

 the valve against the valve-seat, a piston is used on the upper part of the 

 valve, which has an area slightly exceeding that of the ports. The steam 

 pressure on this piston is taken off by friction rollers on the valve-chest 

 cover. As may be seen, this valve has very little more fitting surface than 

 a .common valve, and will cost but a trifle more. The valve is nearly bal- 

 anced, and what friction there is, is mostly rolling friction. The usual 

 steam passages, as now made, are here dispensed with, by wliicli a great 

 saving of steam is here effected; and the cooling surface, which, for each 

 stroke in the common engine, has to be cooled off by the exhaust steam 

 and heated again by the live steam entering, is thus reduced to the least 

 possible area. 



Mr. J. K. Fisher. — A valve made partl^'^ on this principle, by Mr. Buchanan 

 of this city, was tried on some locomotives, but did not succeed, and has 

 been abandoned. The last I heard of it was that the engines worked 

 better with the old valve. 



On motion, Mr. Fisher, Dr. Rowell and Mr. Bartlett were appointed a 

 committee to examine this valve. 



Mr. Shaw, of the New York Lead Company, 63 and 65 Centre street, 

 exhibited several specimens of their patent tin-lined lead pipe, the dis- 

 cussion of which was reserved, as it would form the subject of the next 



discussion. 



-j 



The Cause of the Bursting of Guns. 

 . The Chairman. — As the discussion of this question involves the force of 

 gunpowder, it would be proper to present, at the outset, the latest views 

 of those who have given the subject special attention. A very able paper 

 appeared in the last number of Silliman's American Journal of Science and 

 Art, written by Frof. F. A. F. Barnard, which Dr. Rich has kindly consented 

 to read. 



