Shells

(Me age), are nothing more than howitz shells, in the inside of which a letter, or other papers, are put. The fuze-hole Js stopped up with wood or ‘cork, and the shells are fired out of a royal or howitz, either into a garrison or camp. It is supposed that the person to whom the letter is sent knows the time, and accordingly appoints a guard to look ‘out for its arrival. To find the weight of an iron shell.— Take nine sixty: fourths of the difference of the cubes of the external and internal diameters, and it will give the weight of the shell in ounds.