84: ANNUAL OF SCIENTIFIC DISCOVERY. 



was spread over a space of 5, GO), 000, 000 square yards, and reduced 

 its effective force on the houses oi th-3 metropolis to about six ounces 

 per square yard. It may seem surprising to many that this small 

 force should have been so distinctly felt ; but when it is remembered 

 that a very few pounds exerted in banging a door will give rise to a 

 very severe feeling of concussion in most houses, the surprise will 

 cease. The pressure which would be exerted upon the houses of the 

 metropolis by an explosion atPurfleet, of three pounds or four pounds 

 per square yard, would probably be sufficient to break most windows 

 facing in its direction, and houses would feel the shock very severely ; 

 for, though the pressure would not be more than that specified above, 

 the wave of force arising from such a quantity of powder would be 

 of great duration. 



IMPROVEMENTS IN THE SCIENCE OF WARFARE. 



The Ship of the Future, impregnable and unconquerable. The 

 London Mechanics'* Magazine, in the following interesting sketch, 

 gives some hints as to what will be required for effective harbor de- 

 fence, and what can be done to make a coast line impregnable to an 

 enemy. It says : 



"Let us take a plunge into the future, and describe the ship or 

 gunboat which can best defend our shores. She will possess three 

 paramount qualifications : Firstly, she will carry guns capable of 

 playing havoc with any ship from distant ports able to live in such 

 seas as she would have to encounter in order to reach our coast ; 

 secondly, our ship of the future will steam fast enough to run along- 

 side any foe at her pleasure, or to retreat, when that very objectiona- 

 ble step is dictated by the necessity for drawing the foe into a region 

 where she can be properly attacked; and, thirdly, she will be so 

 heavily armored that an enemy's shot shall fall harmless from her 

 sides. 



These characteristics can only be obtained at the expense of many of 

 those qualities the possession of which can alone render a man-of-war 

 fit for foreign service ; and this is well, because the right ship is cer- 

 tain to remain in the right place only when thera is no other place to 

 which she can go. Let us treat of her armament, in the first instance. 



As regards sub-marine artillery, many recent experiments prove 

 conclusively that the discharge of the heaviest ordnance beneath the 

 water level, is not only practicable, but that the effort of the missiles 

 so discharged is terribly destructive at .short ranges. Our future 

 ship will carry two 20-ton muzzle-loading guns ; we imagine that 

 guns of the Blakely or Parrott class will b-j found most suitable. 

 These guns will habitually use comically-fronted elongated shells, 

 and heavy charges of powder. On board, two or more " wells " will 

 be constructed, or rather two water-tight compartments into which 

 the sea can be admitted, or from which it can be excluded at pleasure. 



For six feet or thereabouts, above the water-line the ship about 

 250 feet long will be very heavily plated, the plating at that 

 height terminating in a shot-proof deck. Two inches of iron on six 

 inches of teak and strong deck beams will go far to make this deck 

 all that is required, as shot must always strike at a very obtuse 

 angle. A second deck will be provided at or about the water-line, 



