MECHANICS AND USEFUL ARTS. 119 



into the ship ; therefore, no iron-clad, whether iron-built or 

 wooden-converted, should be without an inner skin. i;3th, The 

 bolts known as "Palliser's bolts" are the best for securing 

 armor plates. In these bolts the diameter of the shank is 

 reduced to that Avhich it is at the screwed end. The author of 

 the paper preferred the English punching system of higli charges 

 with small shot to the American racking system of heavy cast-iron 

 shot propelled with low charges, on the ground that by the former 

 method, a ship might be sunk, or some vital part injured, in much 

 less time than would be required to destroy her by the American 

 system. — Beport of British Association, 1866. 



