PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 467 



and but little radiating surface, and are set in pairs and so arranged that a 

 strong draught through inclined tubes is attained without blowers ; but little 

 thickness of metal is interposed throughout the whole boiler, between the 

 fire and the water. 



The wheels arc Irving's patent, sixteen feet in diameter, and five feet 

 face, entirely of iron. On the shaft of each wheel is a core-wheel five feet 

 in diameter, with wooden cogs, ten inches face, into which works a cut 

 pinion, twenty-four inches diameter on the engine shafts. The engines 

 make 100 double strokes while the wheels make forty revolutions. By the 

 use of these wheels and these devices I attain lightness that is very essen- 

 tial, absence of noise and jarring or trembling of the light frame-work of 

 the boat. 



The bulk-heads are five in number, made of double thickness, of pieces 

 sixteen feet long, six inches wide, and one inch thick. These pieces 

 are matched with a tongue and groove like common flooring, and put 

 up for the fore and aft bulk-heads, inclined diagonally in opposite direc- 

 tions, and are clinker clinched with wrought nails at each intersection or 

 crossing of the parts; four other bulk-heads are inserted, as shown by 

 dotted lines on the cut showing the elevation of the boat. 



The quartei's for the men are between decks and below well lighted, and 

 ventilated by sashes under the seat on the promenade deck that reach the 

 whole length of the oflScers' cabin on each side. Between decks is the 

 kitchen, a store-room, a machine-shop, stalls for thirty horses, and capa- 

 cious water-closets for men and officers; and oh the promenade deck are the 

 officers' quarters, a long mess-room, state-room, and two pilot-houses with 

 passages. 



The spars for hoisting are so placed as to be convenient for putting off 

 or on the launches, guns and carriages, and the horses. Each spar is fur- 

 nished with geared winches, and the boom is so rigged as to have its peak 

 raised or lowered to lay down or take up articles at any distance within its 

 radius from the foot of the spar. Horses are put in and out by the use of 

 canvas slings buckled about their bodies, the slings having loops on the 

 backs to attach the hook of the tackle on the boom. The plank of the bot- 

 tom is all fastened with copper-covered rivets; this manner of fastening 

 gives great strength with lightness, and the bottom is coppered. 



With the coast of Virginia, North Carolina, South Carolina, Georgia, 

 Florida, Alabama, Mississippi, Louisiana, and Texas to assault and defend, 

 the whole of which is a net-work of shallow waters, of sounds, bays, inlets, 

 rivers and creeks, with only a few places where it can be approached with 

 heavier ships, it would seem to be indispensable that the government 

 should have a great number of the fast and light-draug-ht steamboats above 

 described, which, from their peculiar adaptation and equipment, would seem 

 to be especially calculated for that duty, and designed to meet all the con- 

 ditions required. 



Their speed will enable them to retreat to shallow water from any enemy 

 afloat, and a retreat to the launches or boat, from an assault on land, would 

 insure the safety of the party; while for secret expeditions up creeks or 

 rivers, or into a more easily approached harbor in the night, their assault 

 would be very formidable. The enemy, too, could be watched from seven 



