150 Ocean Wave Poiuer Machinery. 



the bearings, and actually stationaiy at those points.* But 

 reference to the theory of action will show that such an 

 arrangement is practically unessential. 



For the motion or play of the mass, or load, is resisted at 

 all points only by the work to be done. The actual play or 

 movement may consequently be reduced at pleasure by 

 increasing the resistance or work imposed upon it : every 

 such governance being self-acting ; in accordance with the 

 fundamental principle of dynamics, that the mechanical 

 efficiency, or work done, is not diminished by diminishing 

 the play and increasing the resistance. The play, therefore,, 

 of a few inches is equall}^ as efficacious as if the mass have 

 almost untrammelled motion. The movement may, there- 

 fore, be made so small as to be wholly inappreciable in regard 

 to its effect upon the ship ; and a double purpose so served 

 in economy of space. For as the dead weight which has 

 to be carried in a ship may be employed as the moving 

 mass, the loss of space is the extent of the movement 

 only, which may be thus indefinitely reduced. In practice 

 it is proposed in such a case to employ a moveable deck or 

 frame carrying fifty tons or upwards of dead weight, with 

 an allowed movement of no more than twenty inches."!' 



The mode in which it is absolutely confined between fixed 

 limits is by directly connecting the movement of the mass 

 with throttle valves, which cut off the space into which the 

 au" is compressed ; and by a governor regulating the 

 outflow of compressed air into the engine. 



By these means the density of the air is sustained at a 

 degree proportional to the power supplied, i.e., to the 

 violence of the oscillations, so that resistance increases in 

 proportion to the magnitude of the force represented 

 by the oscillations ; or, in other words, the work imposed is 

 kept precisely equal to the power supplied, and the extent 

 of the movement thereby controlled. In fact, if the resist- 

 ance be increased so much by wholly or partially closing the 

 valves, as to equal the relative force in the mass arising from 

 the action of the wave forces, the movement would be 



* As some misconception has been published on this subject, it may be 

 as well to state definitely, that when so referred to three axes at right angles 

 to each other, it is mathematically impossihh for the movements of the 

 independent load to affect in the slightest degree in any way, the stability 

 of the ship, other than if it (the load) were rigidly fixed. 



t The machinery itself will occujDy the same space as the engines and 

 boilers of a steam engine ; the parts being analogous, the saving being in 

 the large space occupied by c(5kls. 



