ON WAVES. 431 
quently the depth of the fluid was uniform across the whole 
depth of the channel ; it was next of importance to ascertain what 
law held in those cases where the depth diminished towards the 
edges of the channel. For this purpose two channels were 
selected having the greatest depths in their middle and diminish- 
ing towards the sides. The following are the results : 
Greatest depth in 
the middle of Space described. Velocity of wave. 
the channel. 
(13.) 5°5 feet 1000 feet 7°84 miles an hour 
(4) At 820 — _— 609 
In these instances the diminished depth at the sides has 
diminished the velocity of the wave below that due to the 
greatest depth in a ratio in the first example nearly of 9°5 to 
Ag} and in the second of 7: to 6°. See Experiments (11) and 
(12). 
The following three experiments are instructive as having 
been made on channels in which the maximum depth was 
nearly the same in all; but in (15) the depth remained con- 
stant to the side which was vertical. In (16) the sides had a 
slope of nearly 20°, and in (17) a slope of nearly 40°, so as to 
diminish the depth towards the sides. 
Maximum depth. Eh Space described. Velocity. 
(15.) 5°6 feet Rectangular 486 feet 9°59 miles 
(16.) 5°5 — Slope of 20° 2038 — 8:83 — 
(17.) 5°5 — Slope of 40° 1000 — 7:84 — 
From these it is manifest that the depth of the channel, while 
it modifies the depth of the fluid, affects the velocity of the 
wave. It was not found that the breadth of the channel pro- 
duced any similar effect. 
The results obtained from the experiments of 1834 and 1835 
were considered by the Association of sufficient novelty and 
importance to point out the propriety and advantage of institu- 
ting a fuller and more minute series of experiments concerning 
the nature of the wave, in which all its phenomena and laws 
should be determined with as much precision as possible. 
The subjects of inquiry which immediately presented them- 
selves were the following : 
1. To determine whether different methods of generating the 
wave influence its subsequent phenomena. 
2. To determine with accuracy the velocity of the wave in 
given circumstances. 
3. To ascertain the form or forms of the wave. 
