ON WAVES. 439 
the top of the wave, ascertained from the mean of three observa- 
tions in each distance of 40 feet. 'The waves were generated by 
four different methods, the depth of the fluid and the height of 
the wave are different in each; so that on comparing them to- 
gether, we have to take into consideration the variations of the 
conditions. Now between the mean interval of the successive 
transits in XIX. and XV., the difference is only two-hundredth 
parts of a second, and between the mean height of the wave in 
the former case, and in the latter, there is a corresponding dif- 
ference with the same sign, amounting to two-hundredth parts 
of an inch—between VIII. and VII. the same coincidence ex- 
ists. The same harmony runs through that whole series of 
observations from Wave I. to Wave XXVI., and appears to 
warrant the conclusion, that between waves of this order, gene= 
rated in very different methods, no sensible difference in the 
law of propagation can be distinguished. In the remaining series 
of observations, the protrusion of solid C was the method gene- 
rally adopted for generating the waves, as it was found conve- 
nient and precise. Various other methods, such as suspending 
the fluid by atmospheric pressure and the immergence of bodies 
of different forms, were tried, without sensible difference on the 
result. 
Waves were then generated in different depths of the fluid, 
and having different heights, for the purpose of determining the 
velocity due to them with all the precision which the method 
was capable of affording. The three columns of figures which 
follow, are a short table of results, and in a fourth column are 
given a few theoretical numbers, representing the height due to 
half the depth of the fluid, reckoning from the ridge of the wave. 
The first of these columns gives the total depth reckoned from 
the top of the wave, the second column is the height of the wave 
Hie above the quiescent fluid, and the third the observed ve- 
ocity. 
