Ocean Wave Poiver Machinery. 151 



reduced to zero, i.e., no work would be done and the mass 



would move ahsoliUely witli the ship, as a rigid part of her. 



It will be seen that in the application of the principle, 



compressed air is proposed to be used for three several purposes. 



1st. As an elastic medium on which the load is poised. • 

 2nd. For storage of power. 

 3rd. For regulating velocity. 



It is not however absolutely essential to the principle, 

 and other means for effecting these objects can be employed. 

 It is however cheap and always accessible ; but on the other 

 hand, its alternate expansion and contraction will engender 

 differences of temperature necessitating the use of further 

 machinery to overcome ; unless indeed the difference of 

 temperature itself be applied to a useful purpose. 



Instead of freedom in three dimensions, the apparatus 

 may be so constructed as to have freedom only in any one 

 or two dimensions. Thus, in a combination of the first and 

 second dimensions, the independent mass would be free to 

 move in the plane of the deck only or upon curved surfaces 

 upon the plane of the deck by the apparent action of gravity; 

 apparent only because the relative rise or fall may be abso- 

 lutely the reverse. The actual motions of any point in a 

 vessel oscillating on waves, and the relative motions of a 

 body free to move within her at that point, include many 

 difficult problems too abstruse to be briefly mentioned here, 

 but the investigation of which, with the result of actual 

 experiments on the subjects now being prepared, will be 

 shortly submitted. In a paper previously read (at the Royal 

 Society of Victoria,) it was however shown that the oscilla- 

 tion of a ship amongst waves is compounded of three 

 simultaneous oscillations, vertical, horizontal, and angular ; 

 and there can be no oscillation at all in which any one of 

 these three be absent. That is, for instance, a vessel or 

 any part of her cannot oscillate vertically without also a 

 horizontal sway and an angular deviation and vice versa. 

 Hence, as the whole oscillations of a vessel are practically 

 unceasing as long as she is on the open ocean, so also are 

 each of these. This fact is of great consequence in esti- 

 mating the efficacy of the various forms of construction 

 wliich the principle may assume ; ■ the writer having 

 experienced a good deal of difficulty in removing the 

 prevailing error, that the mere roll of a vessel is equivalent 

 to her whole oscillation. The rolling is only a part of the 



