328 Charges of greatest Efficacy for Artillery at Sea. 



which is not strictly true; since that resistance depends 

 partly on the quantity of the surface resisted, which con- 

 tinually varus until the ball has penetrated to the depth of 

 This; when it continues uniform till it arrives at the 

 fu h r surface of the object; where the resistance a^ain 

 co nuitncea ts variation. These deviations from uniformity 

 are about sufficient to set against that of the law of variation 

 of the charges before mentioned; the velocities from them 

 filing somewhat :>hort of the law there prescribed after a 

 certain charge. 



Example I. 

 An enemy's ship is in sight ; required the charge for the 

 42 pounder guns to destroy her as quickly and completely 

 as possible when the ships have approached near to each 

 other: the side of the enemy* s vessel (a seventy four) being 

 1*. foot thick of' oak timber. 



The diameter of a 42-pounder of cast-iron being ='557 



foot; we get '045 x - £-- - = 6'8S306lbs, 



D 



or 



6lbs, 



14ozs. for the weight of the charge required. 



TABLE 



Containing the various charges for the 12-, 18-, 24-, 32-, 

 36- and 42-pounder guns, for producing the greatest 

 effect in all cases of action : the substance or object being 

 of oak materials, and its thickness together with the ra- 

 dius of the ball from 1 foot to that of 5 feet, regularly 

 increasing by 1 in the inches. 



