490 



EXPLANATION OF THE PLATES. 



Depth of centre of gravity of displacement below the load water line, 5 

 feet 25 inches. 



Feet. Inches. 



Diameter of cylinder 5 



Length of stroke 5 2 



Diameter of air pump 3 



Length of stroke 3 



Diameter of paddle wheel 22 



Breadth of ditto . 9 7 



Average consumption of coals, 1 8 cwt. per hour. 



It would be impossible to deduce any rule to shew the exact relation between 

 the velocity of the vessel and that of the wheel, for the want of some instrument 

 that would mark accurately the speed of the vessel. With this multiple, however, 

 we may determine nearly the relative perfection of different steam vessels, when 

 the surface and position of other floats are in the same relation to each other ; and 

 by a proper register of these numbers, the relative perfection of paddles on the 

 same vessel may be determined by bringing her under the same circumstance as to 

 draught of water, &c. 



SCANTLINGS, ETC. 



