76 



ANNUAL OF SCIENTIFIC DISCOVERY. 



produced by the round-ended one, which is 3^ times greater. Hence, 

 we derive this remarkable deduction, that whilst the statical resistance 

 of plates to punching is nearly the same, whatever may be the form of 

 the punch, yet the dynamic resistance or work done in punching is 

 twice as great with a round-ended punch as with a flat-ended one. 

 This, of course, only approximately expresses the true law ; but it ex- 

 hibits a remarkable coincidence with the results obtained by ordnance 

 at Shoeburyness, and explains the difference which has been observed 

 in these experiments, more particularly in those instances where 

 round shot was discharged from smooth-bored guns at high velocities. 

 To show more clearly the dynamic effect or work done by the weight 

 of shot which struck some of the targets at different velocities, the 

 following results have been obtained : 



From the above it will be observed that the two last targets have 

 sustained in work done what would, if concentrated, be sufficient to 

 sink the largest vessel in the British navy. 



We are all acquainted with the appearances and physical charac- 

 ter of artillery, but few are conversant with the nature of the opera- 

 tions and the effects produced by shot on the sides of a ship, or on re- 

 sisting forts and targets. 



The shot of a gun is simply the means of transferring mechanical 

 power from one place to another. The gunpowder in the gun devel- 

 ops, by its combustion, a certain quantity of mechanical force, or 

 work, as it is now called, and the object of the shot is to convey this 

 work to a distance, and apply it to an object supposed to be other- 

 wise inaccessible. The effect of this, according to Mr. Pole's for- 

 mula, is 



W = weight of the shot in pounds. 

 V = its velocity in feet per second. 



Then, by the principle of vis viva, the quantity of work stored up 

 by the moving mass, measured in pounds, one foot high, is 



WV2 



g being the force of gravity = 3 



Thus, if we have a shot, like that recently used against the War- 



