784 



SCIENCE. 



[N. S. Vol. IV. No. 100. 



the latter the largest built up steel rifle 

 thus far constructed has been one of 12-inch 

 caliber, 40 calibers in length, weighing 57 

 tons. This is not yet ready for use. A 16- 

 inch rifle, very nearly as massive as the 

 great Krupp gun, has been ordered and 

 will probably be finished within the next 

 two or three years. A number of 12 -inch 

 34- caliber guns have been finished, tested 

 and mounted. 



In assembling the parts of the large 40- 

 caliber gun, at the Water vliet Arsenal gun 

 shop a few months ago, an unfortunate 

 mishap occurred. After the tube had been 

 reenforced near its forward end with a 

 series of hoops it was prepared for the 

 more formidable work of shrinking on the 

 large jacket. It was stood up vertically 

 upon the breech end, and the heated jacket 

 was let down into position. The heating 

 proved to be insuflBcient to secure all the 

 expansion needed, and as a result the cool- 

 ing jacket gripped the tube before quite 

 reaching the final position intended. An 

 interesting problem was now presented, that 

 of separating the tube and jacket after they 

 had become thoroughly cool, and complet- 

 ing the process which had been so unex- 

 pectedly interrupted. 



After due consideration the plan which 

 seemed most promising of success was to 

 introduce the cold gun, with breech down- 

 ward, as suddenly as possible into a fur- 

 nace, protecting the exposed part of the 

 tube below the jacket from the heat by en- 

 closing it in a bag of asbestos cloth through 

 which a strong blast of cold air should be 

 propelled. The jacket being thus heated 

 first, while the tube within was compara- 

 tively cool, it was hoped that expansion 

 enough might be attained to ensure separa- 

 tion. In order to keep the greatest pos- 

 sible diff'erence of temperature between 

 jacket and tube, a flow of cold water through 

 this was set up immediately after its em- 

 placement within the furnace. The breech 



had been closed water-tight. A pipe occu- 

 pying the axis of the bore was coupled at 

 the top with hose from an elevated tank 

 full of ice water, and this was carried thus 

 to the bottom. After it had filled the tube 

 it was carried off" by an overflow pipe. The 

 jacket, or certainly its lower part, was 

 quickly raised to a temperature estimated 

 to be about 1100° F. The temperature 

 gradients from outer to inner surface would 

 obviously be curves, at first sharply con- 

 cave upward, but gradually approaching 

 straight lines as the heating continued. 

 It was hoped that, before the equilibrium 

 expressed by the straightening of these 

 gradients should set in, the jacket would 

 become expanded enough to settle down 

 by its own weight into the desired final 

 position. 



But this hope was doomed to disappoint- 

 ment. The external heating and internal 

 cooling was continued nearly eight hours 

 on January 27th, the flow of ice water being 

 kept quite uniformly forty cubic feet per 

 minute. Its temperature was raised from 

 34° to 40° F. in transit, with but little vari- 

 ation after the first two hours. The water 

 was then discontinued and the supply of 

 heat kept up through the night. On the fol- 

 lowing day the experiment was renewed, 

 but varied by trying the effect of sudden 

 cooling from within. On admitting the 

 supply of ice water there was naturally 

 much steam produced at first, but within 

 fifteen minutes the temperature difference 

 between inflow and outflow fell to 36°. 

 At the end of two hours it had fallen to 9°, 

 and during the remaining six hours it con- 

 tinued quite uniformly about 8°. This dif- 

 ference was in excess of that of the previous 

 day, as it had been found necessary to re- 

 duce the rate of water supply. This ex- 

 periment being unsuccessful, the gun was 

 removed from the furnace and allowed to 

 cool. 



The furnace had been originally con- 



