118 APPENDIX. 



float of the common wheel, and so passed the middle of the stroke ; after which it was again 

 made to turn on the same radial axis, so as to come out of the water in the same manner as it 

 went in. In these the shock and back water are, no doubt, in a great measure avoided, but 

 the loss of power from oblique action is still greater than in the common wheel; the con- 

 trivances also for causing the floats to take the required positions are all very objectionable in a 

 mechanical point of view ; so that no advantage has been found to result from the use of 

 wheels constructed on this principle. A wheel of this description was patented in the year 

 1828 by Messrs. W. and J. Stead, another by Messrs. W. and A. Symington in 1834, and a 

 third was invented in 1829 by Mr. A. Heilbronn, of New York. 



In the wheel invented by Lieutenant Skene, R.N., in the year 1828, each float was 

 suspended on a horizontal axis, and its lower part loaded with metal, so as to cause it to 

 enter the water in a vertical position ; by the time it had reached the middle of the stroke, 

 a projection on each side had come in contact with the arm of the wheel, causing it then to 

 act precisely as a common radial float to the end of the stroke. It was tried on the ' Sons of 

 Commerce' Gravesend steam boat, and the performance was found to be better when the floats 

 were lashed to the arms, than when free to act as intended by the inventor. 



In some wheels the floats have been fixed obliquely, so as to enter and leave the water 

 more gradually, in order to diminish the shock and back water ; but the action is more oblique 

 than that of the common wheel. A patent was obtained by Mr. S. Hall in 1836 for a 

 wheel of this description. Mr. J. Perkins proposed to place both the floats and the shafts 

 obliquely ; and other arrangements, too numerous to be detailed here, have been proposed, 

 mostly with the object of reducing the shock and back water, without regard to the oblique 

 action. 



In 1827, Mr. J. Oldham took out a patent for a very ingenious method of giving each float 

 exactly half the inclination of the radius passing through its centre. By this means the shock 

 and back water, as well as the loss of power from oblique action, were very much reduced ; but 

 the objection in practice to the use of spur wheels, by means of which the feathering of 

 the floats was effected, has prevented this wheel from being generally adopted. Several other 

 modes of producing the same effect have been contrived, but similar objections apply to 

 them all. 



A wheel which has been employed to a considerable extent is that generally known as 

 Morgan's wheel. In this the floats may be made to enter and leave the water at any required 

 angle, which is therefore regulated in each wheel according to the relative velocities of the 

 wheel and the vessel ; and the machinery for this purpose does not appear to have been attended 

 with any serious inconvenience in practice. Since 1829, the date of the patent, a consider- 

 able number of government and private steam vessels, both English and foreign, have been 

 fitted with wheels of this construction. In the year 1829, Mr. Poole took out a patent for a 

 wheel in which the action of the floats is the same as in Morgan's wheel; this effect is 

 however produced by means of a very different contrivance, which is attended with several 

 disadvantages. Another wheel, very similar to Morgan's, was invented by Mr. Cave, engineer 

 at Paris, in 1827, but the action of the floats was much less uniform in consequence of a 

 difference in its construction. 



A modification of the common wheel was tried in the year 1833 by Mr. Jos. Field, the 

 object of which was to reduce the shock and back water, without impairing the effect of the 



