navigating the Hudson River, 5 



the rudder, is vertical ; an unusually large mass of dead wood 

 therefore exists towards the stern, while there is but little near 

 the bow. I have not considered it proper to apply to Mr. 

 Stevens for a draught of the hull of this vessel, as it would be 

 unfair to ask him to disclose what is his only safety from the 

 imitation of his competitors. The North America is impelled 

 by two condensing engines, each of the estimated power of 85 

 horses. These, with the boilers, are placed upon a platform, formed 

 by a prolongation of the beams of the deck, until they meet the 

 wheel guards, which are carried in a regular sweep from the 

 stem to the stern of the vessel. The breadth of the deck, afore 

 and a])aft the buildings which inclose the wheels and machinery, 

 is therefore considerably increased^ while an uninterrupted pas- 

 sage is left between them from the stem to the stern of the 

 vessel. An advantage similar to the last is gained in the cabins 

 beneath, which, by opening folding doors, may be thrown into 

 one suite from the cabin windows to the bow. 



The wheels are 13 J feet in breadth, and 21 feet in diameter. 

 There is a peculiarity in their construction which I conceive to 

 be one of the most important of the improvements for which 

 steam navigation is indebted to Mr. Stevens. Experience had 

 shown that a multiplication in the number of paddles (as is the 

 case in an undershot water-wheel, and is there of value) is 

 injurious in a steam-boat. The best arrangement is, that 

 when one paddle is vertical, the preceding one shall be just 

 quitting the water, and the succeeding entering it; in this 

 way no more than two paddles can be in the water at a time, 

 while a water-wheel works best when there may be four. 

 There appears to me to be an obvious reason for the difference 

 between a wheel propelled by a water-fall, and one acting upon 

 water as a resistance to propel a vessel. In the first case it 

 is advantageous to check the forward motion of the water ; in 

 the second, the paddle will act with most power upon water at 

 rest, with respect to the surrounding mass. Now the more 

 numerous the paddles, the greater the agitation that is pro- 

 duced ; and each will in succession strike on water following 

 in the wake of that which has preceded it, and which there- 

 fore acts as a less powerful resistance. But the paddles strike 



