November 27, 1896.] 



SCIENCE. 



785 



structed of such dimensions as to permit 

 of heating the longest jacket, but not an en- 

 tire gun. Since the breech and unjacketed 

 part of the gun under present conditions 

 had to occupy space within the furnace, an 

 extension of this at the top had to be im- 

 provised to enclose the upper part of the 

 jacket. Soon after the experiment began it 

 was observed that the heating was by no 

 means uniform, and by no supplementary 

 efforts could uniformity be secured. 



Measurement upon the cooled gun re- 

 vealed the fact that the jacket had changed 

 its position nearly half an inch, but this 

 was only one-twentieth of the shifting 

 needed. It was not surprising also to find 

 that the whole assemblage was perceptibly 

 warped. 



The method, applied on so large a scale 

 and under conditions which had precluded 

 the possibility of uniform heating, had failed. 

 But theoretically it seemed unassailable. It 

 was decided to test it again under more 

 favorable conditions. The construction of 

 a new large gun for this test would ob- 

 viously involve an unwarranted expense ; 

 for the cost of a completed 12-inch gun of 

 this type is not much less than $60,000. A 

 short ' dummy ' gun was therefore con- 

 structed, of 8-inch bore and 3 feet in length. 

 This was provided with hoop and jacket, 

 which were shrunk on tightly into position, 

 a special furnace being built for the purpose 

 of the experiment. The piece was inserted 

 into the hot furnace, the water turned on 

 to the interior, and at the end of 3 minutes 

 the jacket suddenly dropped 4 inches. 

 It continued then creeping downward at a 

 moderately uniform rate, and dropped en- 

 tirely off from the tube at the end of 42 min. 

 30 sec. The temperature of the inflowing 

 water was 58° F. and that of the outflow 

 67° F., no attempt being made to secure 

 artificial cooling by use of ice. 



The success of this experiment, which 

 was made on the 31st of March, caused 



the decision to make another trial with the 

 large gun. This was started on May 11th, 

 extra precautions being taken to secure 

 uniformity of heating. An auxiliary grate 

 had been prepared for the furnace exten- 

 sion above, and with a view to securing the 

 highest heat as close to the jacket as possi- 

 ble baskets of heavy wire netting were 

 filled with charcoal, inserted in the furnace 

 and brought close up around the gun after 

 its insertion. At the same time water at a 

 temperature of 68° F. was turned on, as it 

 had been found impossible to secure a suffi- 

 ciently rapid supply of ice. The elevation 

 of temperature in transit was at first 5° F., 

 and this rose in time to 11° F. At the end 

 of 22 h. 30 min. the jacket having remained 

 immovable, the fire was drawn from the 

 furnace, while the water supply was con- 

 tinued 15 hours longer, until the gun was 

 thoroughly cooled. 



It is but due to say that, although this 

 experiment has proved an instructive fail- 

 ure, the gun is not lost to the ordnance de- 

 partment of the government. The un- 

 jacketed part of the breech will be cut off, 

 and the final outcome will be simply a gun 

 somewhat shorter than provided for in the 

 original specifications. 



But the question may be asked, will this 

 gun be so reliable as it would have been 

 without passing through so many fiery 

 ordeals ? After each furnace trial it was 

 carried back to the shop and the degree of 

 warp ascertained by measurement. Its 

 exact condition between the locking of the 

 jacket and the first attempt to move this 

 is not known. The present warp of the 

 axis between the breech end and the sup- 

 port near the muzzle end of jacket is 0.1855 

 inch, and from here to the muzzle end of 

 the gun, 0.1561 inch in the opposite direc- 

 tion but in the same plane. Between the 

 first and second attempts at removal there 

 was no noticeable variation of result. The 

 interior diameter of the bore within the 



