THE UNITED STATES OF AMERICA. 115 



Number of revolutions . . 26 



Velocity of vessel per second . 19'95 feet. 



Relative velocity of wheel per second 6'3 feet. 



Whole velocity of wheel . 26-25 feet. 



The passage whence the above data were derived, was performed in thirteen hours and a 

 half, and does not differ materially from the average of those now usually performed. 



It would thus appear that no very great increase of speed has been gained in the steam 

 boats used in river navigation since the construction of the ' North America.' As to those 

 which navigate the Sound, the improvement in velocity is considerable, but seems to be 

 attended with a loss of good qualities in other respects. But we are not to estimate the value 

 of the new models from speed alone. It is in the duty of the engines, or the effect produced 

 by a given quantity of fuel, that the newly constructed vessels manifest their superiority. 

 Not only is the size and nominal power of the engines used in boats of given dimensions 

 lessened, but the fuel Consumed in the passages is diminished in a still greater ratio. Thus 

 the ' Erie ' and ' Champlain,' boats of a newer construction than the ' North America/ but 

 modelled after her, have each two engines 44 inches in diameter, and 10 feet stroke ; while the 

 ' Rochester,' 20 feet longer than either, and of two feet less beam, has no more than one 

 engine of the'same dimensions. In comparative speed the ' Rochester 3 has the advantage over 

 the others. The two vessels belonging to the Port of New York, which have the highest 

 reputation for speed, are the ' Passair,' and ' Cornelius Vanderbitt.' The former was con- 

 structed by the younger Stevens, and the latter is said to be as near a copy of her dimensions 

 and model, as could be constructed without direct reference to the original moulds. The ' Pas- 

 sair' has not come into direct competition with the vessels which navigate the Hudson, but 

 the ' Cornelius Vanderbitt' exceeds them all in speed. The superiority of this vessel, how- 

 ever, rather consists in the capacity of arriving first at the several landings, in the case of a trial 

 of speed, than in any great reduction of the average time of passage. In fact, to gain several 

 miles in the course of a passage amounts to no more than a saving of a very few minutes of 

 time. 



Our view of the subject would be incomplete, did we not refer to a vessel which has been 

 for some months in preparation in the port of New York, for the purpose of running between 

 that city and Liverpool. In this vessel a new form of boiler has been introduced, the prin- 

 ciple of whose action is, that the combustion shall be maintained by air forced into a furnace 

 without a chimney, and that the air, after acquiring, by the joint effect of compression and 

 elevated temperature, a tension equal to that of the steam, shall open a valve by which it may 

 join the steam in its passage to the valves of the engine. A sufficient number of experiments 

 have been performed with this boiler, to show that it will produce a given effect at a vast 

 saving of fuel, but various practical difficulties seem to oppose its perfect success. 



In conclusion it may be stated, that in respect to speed the steam boats of the Hudson 

 exceed any others, have attained a velocity which is hardly believed to be possible in 

 Europe, and are for the navigation of rivers unequalled. The same principles, modified 

 according to the circumstances of the case, may be applied to give a greater velocity to vessels 

 intended for the navigation of the ocean than has yet been attained by the English steamers. 

 On the other hand, the vessels constructed in the United States for speed, want some of the 

 essential properties of good sea boats. In the competition and honourable rivalry between 

 the engineers and naval architects of the two countries, which the voyage of the 'Great 



