Sinking U-Boats with a Sub-Sea Barrage 



The Isham shell, which does not ricochet, 

 is the latest destroyer of the submarine 



Bv Robert G. Skerrett 



THE diving shell is the latest thing 

 for attacking hostile submarines. 

 It is the depth- 

 bomb improved and 

 therefore more po- 

 tent. Indeed, in the 

 opinion of many ex- 

 perts the diving shell 

 is the most formida- 

 ble instrument yet 

 devised for battling 

 with the foe's 

 U-boats. It is an 

 out-and-out Ameri- 

 can invention and the climax of years of 

 study and development on the part of 

 its originator, Willard S. Isham. 



Of depth-bombs there are several sorts, 

 but of diving shells there are only two 

 kinds — a foreign adaptation of the Isham 

 missile and the Isham projectile, pure and 

 simple. The reason for this is that the 

 French and British governments have 

 been more alive to the merits of the Amer- 

 ican invention than our own ordnance 

 officials, and, as a result, have actually 

 been the first to apply the diving shell to 

 wartime service. We are catching up, 

 however, if reports from Washington can 



be accepted at their face value, and the 

 so-called "non-ricochet shell" is likely soon 

 to have its place in 

 the magazines of all 

 of our destroyers 

 operating in 

 European waters. 



CvjppediAOse 



How water enters 

 cvjp arvd forms pomt 



High-Angle Fire 

 and Its Drawbacks 



High-angle firing makes the shell strike 

 the water at such an angle that it will 

 dive into the sea instead of ricocheting 



shell resort to 



The British and 

 French vessels that 

 are armed to throw 

 their form of diving 

 high-angle fire, the pro- 

 jectile traveling a course much like that 

 of a missile discharged from a mortar. 

 In this way, the shell strikes the water 

 at an angle sufficiently blunt to obviate 

 ricocheting and to insure penetration 

 into the sea. Once the missile has plunged 

 beneath the surface its explosion is auto- 

 matically regulated. The detonating fuse 

 is set to operate at a predetermined sub- 

 mergence as in the case of a depth-bomb. 

 High-angle fire from a moving craft 

 at an object in motion has a number of 

 drawbacks. First, there is the com- 

 paratively protracted flight of the pro- 



The explosion of the Isham shell beneath the surface is regulated automatically by a time 

 fuse set to operate at a certain degree of submergence regardless of hydrostatic pressure 



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