LOCOMOTION BY RIVER AND RAILWAY. 



continued, and probably will continue, to be the limit of steam 

 navigation in this direction. 



The steam navigation of the Hudson is entitled to attention, 

 not only because of the immense traffic of which it is the vehicle, 

 but because it forms a sort of model for most of the rivers of the 

 Atlantic States. This navigation is conducted, as will be seen, in 

 a manner and on a principle altogether different from that which 

 prevails on the Mississippi and its tributaries. 



In the steam- vessels used on these rivers, no other strength or 

 stability is required than is sufficient to enable them to float and 

 bear a progressive motion through the water. Not having to 

 encounter the agitated surface of an open sea, they are supplied 

 with neither rigging nor sails, and are built exclusively with 

 a view to speed. Compared with sea-going steamers, they are 

 slender and weak in their structure, with great length in pro- 

 portion to their beam, and a very small draft of water. 



The position and form of the machinery are affected by these 

 circumstances. Without the necessity of being protected from a 

 rough sea, the engines are placed on the deck in a comparatively 

 elevated situation. The cylinders of large diameter and short 

 stroke, almost invariably used in sea-going ships, are rejected in 

 these river boats, and the proportions are reversed, a compara- 

 tively small diameter and a stroke of great length being adopted. 

 It is but rarely that two engines are used. A single engine, 

 placed in the centre of the deck, drives a crank placed on the axle 

 of the enormous paddle-wheels. The great magnitude of these 

 latter, and the velocity imparted to them, enable them to perform 

 the office of fly-wheels, and to carry the engine through its dead 

 points with but little perceptible inequality of motion. The length 

 of stroke adopted in these engines supplies the means of using the 

 expansive principle with great effect. 



The steamers which navigate the Hudson are vessels of great 

 magnitude, splendidly fitted up for the accommodation of passen- 

 gers ; and this magnitude and splendour of accommodation have 

 been continually augmented from year to year to the present time. 



9. In the following table (p. 23) we have given the dimensions of 

 nine steamers which were worked on the Hudson previously to 1838. 



Since the date of these returns, considerable changes have been 

 made in the proportion and dimensions of the vessels navigating 

 this river ; all these changes having a tendency to augment their 

 magnitude and power, to diminish their draft of water, and to 

 increase the play of the expansive principle. Increased length 

 and beam have been resorted to with great success. Vessels of 

 the largest class now draw only as much water as the smallest 

 drew a few years ago : 4ft. Gin. is now regarded as the maximum. 



