ON PADDLE WHEELS. 117 



VII. ON PADDLE WHEELS. 



BY ARISTIDES A. MORNAY, ESQ. 



UNTIL within the last few years the construction of paddle wheels, although by no means 

 an unimportant part of the machinery of steam vessels, met with little or no attention from 

 men capable of investigating the action and estimating the qualities of this description of 

 machinery ; and even now we have but few works on this subject, and those generally of a 

 superficial character, by far the most complete being Mr. P. W. Barlow's paper On the Motion 

 of Steam Vessels, published in the Philosophical Transactions for 1834; which, with some 

 important additions, is inserted in another part of this work. 



It is well knoM'n that the common paddle wheel, which has been almost universally used 

 from the time when the steam engine was first applied to the purpose of propelling vessels, is 

 very defective in its action, owing to the great obliquity of the floats ; the immediate conse- 

 quence of wh'ch is the loss of a considerable portion of the power applied, from the reaction of 

 the water not taking place in the direction in which the useful effect is produced. This is 

 what is understood by oblique action. Another disadvantage arising from the above cause is 

 the shock received by each float on entering the water, the resistance being the greatest at 

 that instant, when also the smallest proportion of it is beneficially employed, the obliquity of the 

 floats being greater at the beginning and end than at any other part of the stroke. The rapid 

 succession of shocks so produced causes an unpleasant tremulous motion in the vessel, and 

 occasions a further loss of power by checking the motion of the wheel, and thus impairing its 

 effect as a fly wheel. Another bad effect of the great obliquity of the floats is the back water, 

 or the water thrown up by the floats as they leave the water, and projected towards the stern 

 of the vessel. 



To remedy these defects many different plans have been devised, but few of them have 

 attracted serious attention ; the greater number having been erroneous in principle, and fre- 

 quently extremely inconvenient in practice. 



One of the earliest of these inventions is that of Mr. Robertson Buchanan, for which he 

 took out a patent in the year 1813. In his wheel the floats are made to maintain the vertical 

 position during the whole revolution, and consequently there is no oblique action ; but during 

 the first and last portions of the stroke the floats impinge upon the water with their front 

 surfaces, thus opposing an additional resistance to the progress of the vessel. For this reason 

 Buchanan's wheel has not come into use, although not very complicated in its construction. 

 This wheel, with a very slight modification, was again patented in 1828 by Mr. A. Bernhard. 



Several wheels were so contrived that each float entered the water edgewise, and was then 

 made to turn on an axis radiating from the centre of the wheel until it took the same position as a 



