94 ANNUAL OF SCIENTIFIC DISCOVERY. 



rods inward, it strikes against a lever, which moves like a pendulum, in the 

 fuse tube, and the lower end of the lever breaks or bends a small leaden tube, 

 containing a combustible compound, which is set on fire by coming in contact 

 with some sulphuric acid held in a capillary tube, which is broken at the same 

 time, and so fires the fuse, which communicates with the powder contained hi 

 the chamber at the apex of the cone, and which holds about 9 Ibs. or 10 Ibs. 

 At the extreme apex is a brass ring, to which is attached a rope and some 

 pieces of granite, which moors them about nine or ten feet below the surface, 

 so that the only vessels they could hurt, the gun-boats, float quietly over them. 



TESTING OF CANNON. 



The following notice respecting the plans adopted for the testing of cannon 

 by the U. S. Ordnance Department, at "Washington, D. C. is derived from the 

 Charleston, S. C., Standard. 



G-uns are cast in any shape that may be suggested by the process of invest- 

 igation, then fired to test their projectile force, then fired until they burst ; and 

 when the result has been attained, with every care to determine the causes 

 and conditions of the experiment, sections of the broken metal are carefully 

 drilled out from diiferent parts of the piece, from the muzzle and the breech, 

 and the inside and the outside, and each piece is subjected to a strain to test 

 its tensile strength. In the process of these experiments, one fact has become 

 pretty well established which rather contradicts received opinion. It has been 

 supposed that the cannon, always cooling from without, and the outside con- 

 tracting, therefore, around the inside still extended by heat, would become 

 more brittle, but this, in such tests as have been used, would not seem to have 

 been the case. A bar cut from the outside of the cannon will generally part 

 with about the same amount of extention as a bar cut from the inside, whether 

 it be taken from a longitudinal or vertical section of the gun. Another fact 

 of some importance, however, has been established. It is found that the 

 strength of the gun may be much increased by taking the weight of metal from 

 the muzzle and casting it around the breech. A gun, for instance, had been 

 cast with a view to this experiment, which was much thiner at the muzzle 

 than cannons usually are, but which was by so much the thicker at the 

 breech, where the charge explodes. It was fired some 1200 times, under 

 every conceivable condition likely to insure explosion, and when it did burst, 

 the fracture occurred at the breech, as is usually the case with cannons. 



IMPROVEMENTS IN WAR INVENTIONS. 



The effect of the European war during the last two years has been to bring 

 out an almost innumerable number of war inventions in Europe and the United 

 States. In England it was recently stated in the House of Commons, that 

 within a recent period 974 inventions relating to belligerent implements and 

 schemes had been brought before the select committee of the British Board of 

 Ordnance. Some of the more important ones had been carried into effect, 696 

 had been rejected, and the remainder were then under consideration. 



