covering as to allow the same to recover its original position independently of the new shape or position of the injured and deformed metal plate. Should the india-rubber be placed upon the metal plates and be so attached to the said plates as to adhere and conform to them in or after their deformation, a hole made in the india-rubber would remain open; on the other hand, should the india-rubber without any intermediate substance be attached to the metal plate in such a manner that it will recover its position after perforation, water would penetrate between the metal and the india-rubber, and by the pressure of this water the india-rubber would be liable to be detached from a large area of the metal plate, and so become ineffective or even dangerous to the boat. Moreover, if the india-rubber is fixed directly upon the metal plates, in the case of a shot passing completely through the boat, that is to say, passing into the boat at one side and out at the other side, a large portion of the india-rubber adjacent to the hole made by the shot in leaving the boat will be torn or destroyed, but this will not be the case in boats constructed according to Colonel Fosberry's patent. The French government have recently applied this invention to one of their torpedo boats with very successful results, thereby proving that it is not merely a theoretical idea. _Submarine Boats._--Submarine boats, if they could be constructed to fulfil the conditions hereinafter enumerated which are essential to a perfect boat of that nature, would for many reasons be a very important point solved in connection with torpedo operations, and therefore it is most extraordinary that a practicable submarine boat has not yet been designed and built. _Bushnell's Submarine Boat._--The first submarine vessel built for torpedo purposes was designed and constructed by David Bushnell in 1775. This vessel, operated by a Sergeant Esra Lee, was employed in an attempt in 1776 or thereabouts on the _Eagle_, an English man-of-war, which proved unsuccessful, owing to the sergeant not being thoroughly versed in the management of his curious craft. She was soon afterwards sunk in the Hudson river, but was subsequently recovered by the inventor, though never used again. This vessel was capable of holding one person, and air sufficient to support him thirty minutes without receiving fresh air, and is fully described in 'Barnes's Submarine Warfare.' _Qualifications essential to a Submarine Boat._--A submarine boat should possess the following qualifications:-- 1.--It should be of sufficient displacement to carry the machinery necessary for propulsion, and the men and materials for performing the various operations. 2.--It should be of such a form that it may be easily propelled and steered. 3.--It should have sufficient interior space for the crew to work in.