322 REPORT — 1S44. 



friction of the fluid. At one end, as of the channel G, fig. 4, there is placed 

 the water, which, falling through a given height, is to generate the wave. At 

 the other end, X, is a similar reservoir and sluice, open to the channel. 

 When the wave has been generated as at K, and has traversed the length of 

 the channel, it enters the receptacle X, and assuming the form marked at L, the 

 sluice being suddenh' permitted to descend, the column of water will be in« 

 closed in the receptacle, and its whole volume raised above the level of repose 

 nearly as at the first. The power expended iu wave-genesis, having been 

 transferred along the whole channel, is thus once more stored up in the re- 

 servoir at the other extremity. A part of this power is, however, expended 

 in transitu by friction of the particles and imperfect fluidity, &c. When the 

 channel is large, the sides and bottom smooth, the transmission of force may 

 be accomplished with high velocity, at the rate of many miles an hour, to a 

 distance of several miles. 



Re-genesis of Wave. — In the channel AX, we have found the wave trans- 

 mitted from A to X, and there the power of genesis transferred to the fluid 

 column now stored up in the reservoir X. If we now repeat from the re- 

 ceptacle X the same process of genesis originally performed at G, elevating 

 the sluice and allowing the fluid column to descend, it will again generate 

 a wave similar to the first, only transmitted back in the opposite direction. 

 This re-generated and re-transmitted wave may be again found in the pri- 

 marj-^ reservoir of genesis as at G, and the same power, after having been 

 transmitted twice through the length of the chaimel, be restored as at first 

 in that channel, with only the small diminution of power lost in transitu. 

 The process of re-genesis may now be repeated, as at first, and so on during 

 any number of successive transmissions and re-transmissions. 



Rejleocion of the Wave. — This process of restoring the force employed in 

 wave-genesis, and of re-genesis of the wave, may take place without the inter- 

 vention of the sluices. The wave, on reaching the end of the channel G at 

 Xj, becomes accumulated in the form of the curve w x. We have there- 

 fore the power of genesis now stored up in this water column, w L x, above 

 the level L, and in a state of rest. By means of a sluice we may detain 

 it at that height for as long time as we please. But let us suppose we do not 

 wish to detain it, but allow the water column to descend by gravity as at first, 

 it generates the wave by again descending, and transmits it back towards G, as 

 effectually as if the reservoir had been used, or as the genesis when first ac- 

 complished. By the same process of laissez faire, the power of genesis will 

 be restored at G, a water column elevated, the fluid brought to rest and al- 

 lowed again to descend, again to effect genesis of the wave, and again trans- 

 rait the force along tiie channel through the particles of the wave. The wave 

 is said to be reflected, and it is thus shown in reference to the wave of the 

 first order, that the process called reflexion consists in a process of restoration 

 of the power of genesis, and of re-genesis of the wave in an opposite direction. 

 In this manner there is to be obtained an accurate view of the mechanical 

 nature of the reflexion of the wave. 



Measure of the Power of Wave-Genesis. — If we examine the process of 

 wave-genesis as at K, fig. 2, we find that the change which has taken place 

 after the wave-genesis and before, consists virtually in a different arrangement 

 of the particles of a given volume of water. The given rectangular column 

 of water A P,o occupies after genesis the equal space A K. This, without 

 regard to the paths in which the particles have proceeded to their new places, 

 this descent is the final result and integral effect of the development of the 

 power of the generating column. Take away from these two equal volumes 

 of fluid the volume g p common to both, and the remaining volumes to P and 



