Ce 
a 
ON WAVES. 495 
Description of Plates accompanying the Report on Waves. 
Plate I. contains the apparatus of the experiments on waves. 
Fig. 1, A is a transverse section of the experimental channel, 
the sides of which were made smooth and as nearly plane 
surfaces as possible ; the whole internal surface being divided 
into feet, inches, tenth parts of an inch, &c., for convenient 
observation. B and D are the two ends of the same channel, 
and are elevated, so as to reflect the waves from vertical sur- 
faces. C is the generating reservoir referred to in the ex- 
periments as “‘Generating Reservoir A.” Fig. 2 shows the 
apparatus for observing transits of the wave by reflexion. I is 
the luminous object from which the rays falling on the plane 
mirror M are thrown down on the surface of the fluid at W, 
and thence reflected on the small mirror m, to the eye of the 
observer. W', W®, and W®, show a single wave in successive 
positions, and figs. 3, 4, and 5, show the places of the image 
corresponding to those positions. Fig. 8 shows the generation 
of the wave from “‘ Reservoir A,” by removing the sluice S. 
Fig. 9, B represents the generating chamber, resting on the 
bottom of the experimental channel, and containing the fluid 
which generates the wave when the sides of the chamber are 
raised from the bottom. Fig. 10 represents the solid paral- 
lelopipedon C ; and that part of it towards D represents the 
form and magnitude of the chamber and the solid D. 
Plate IJ. gives the forms of the waves of the sea referred 
to in pages 445—451 of the Report. Fig. 1, the cycloidal 
forms. Fig. 2, a and b, elementary waves, moving in opposite 
directions; cand d, the result of this combination at successive 
instants of time. Figs. 3 and 5 are forms observed to re- 
sult from the combination of three or four co-existent classes 
of waves moving in different directions. Figs. 4, 5, 6 and 7 
show the manner in which waves break, either from the coin- 
cidence of a wave of a higher or with the crest of a lower wave, 
so as to give the form of unstable equilibrium, or from the ex- 
cess of the height of the wave above the depth of the fluid. 
Plate III. exhibits the relation of the velocity of the waves 
to the depth, as taken from the experiments in the rectangular 
channel, fig. 1, and in the channels, fig. 2, H, fig. 3, K, and 
fig. 4, L. ‘The horizontal abscisse are depths of the fluid, and 
the vertical ordinates the corresponding velocities. 
Plate IV. represents the form of a tide-wave as it passed 
