MECHANICS AND USEFUL ARTS. 59 



that the diminution of power will not be important, and, in some 

 instances, there will be a gain in weight of projectile. Thus, the 

 Eoanoke, which originally threw 1,424 pounds from her broadside, 

 and is now converted into a turret ship, will throw 2,700 pounds at 

 an object abeam, when fully armed, and 000 pounds ahead or astern. 

 There must be, however, a material reduction in the celerity of fire 

 with guns and projectiles so large as the eleven-inch, whatever may be 

 the mechanical appliances which may be brought to assist. An eleven- 

 inch gun, with a well-disciplined crew, can be fired once a minute ; 

 but there must be much improvement in any mode now suggested 

 before a fifteen-inch gun can be fired once in triple that time. As a 

 certain capacity for repetition is essential to the general power of a 

 battery, there is thus involved a disadvantage which can only be 

 compensated to any extent by the great concentration of effect in the 

 individual projectiles. For it may be conceived that the effects of 

 shells of three hundred and thirty pounds, and shot of four hundred 

 and fifty pounds, will be damaging beyond any experience in former 

 batteries. What may be the power of such ordnance against iron- 

 cased ships, comparative or absolute, remains to be ascertained. 

 This, as well as the piece itself, is yet but an experiment." 



In conclusion, Capt. Dahlgren expresses his opinion, " that, as the 

 case now stands, the offence has decidedly the advantage, and that 

 no seagoing ship can be considered as impregnable to artillery." 



Thoughts concerning the Unhealihiness of Iron-Clad Vessels. 

 The London Lancet makes the following suggestions respecting the 



O <>O JT t^. 



unhealthiness of iron-clad vessels. An iron-cased ship may afford 

 greater protection to her crew from, shot and shell than a wooden 

 ship, but it has been overlooked that, to whatever extent this protec- 

 tion has been obtained, to a like extent the vessel has been made less 

 fit for habitation. It has been forgotten, in short, that shot-proof 

 ships might require for their due working disease-proof sailors. Ex- 

 perience has again and again shown that, in time of war, for one 

 man lost from the casualties of actual contention, several have been 

 needlessly lost from disease. The conditions which have given rise 

 to this additional, most wasteful, and most unnecessary expenditure 

 of life unhappily exist to almost as great an extent in peace as in 

 war, and the chief of these conditions has been clearly set forth by 

 Lord Paget, secretary to the British board of admiralty, in a recent 

 debate in Parliament. He said, " Everybody who has been on board 

 ship in the lower deck will know that the atmosphere is sufficiently 

 bad to provoke almost any kind of disease, especially phthisis and 

 fevers, as has been shown by the returns from British fleets on tropi- 

 cal or semi-tropical stations." This was said of wooden ships of 

 war ; but when we reflect that in armor-plated ships the portholes 

 are largely diminished in number and greatly lessened in size, and 

 that, the more effectually to strengthen the walls of the vessel and 

 prevent the intrusion of shot or shell, no aperture of communica- 

 tion with the interior is permitted to exist which can possibly be 

 done away with, we are justified in concluding that the state of the 

 between-decks, referred to by Lord C. Paget, will in these ships be 

 greatly intensified. When, moreover, we remember that, from the 

 character of these vessels, and as shown by experiment, the tempera- 



