432 SEVENTH REPORT—1837. 
4. To determine the manner in which the depth and breadth 
of the channel affect the velocity and form of the wave. 
5. To determine the influence of form in the channel on the 
form and velocity of the wave. 
6. To ascertain the nature of the mechanism by which the 
wave is propagated from one place to another; or to answer 
the question, What is the wave? 
7. To ascertain the difference between the primary wave and 
waves of other descriptions. 
8. To determine the effects of solid bodies or obstacles on the 
motion of waves, and the effect of waves on one another, and 
conversely—the effect of waves on solid bodies, either at rest 
or moving through them, immersed in them, or floating upo 
their surface. 
9. To determine the effects of waves on one another. 
For the purpose of obtaining some of these results with the 
requisite precision, there was provided the following 
EXPERIMENTAL APPARATUS, 
Experimental reservoir.—A_ rectangular reservoir, formed 
with much precision, was provided for the purpose of contain- 
ing the fluid to be made the subject of experiment. Its sides 
were supported by strong brackets, and the whole was raised 
on a strong frame to a height convenient for experiment ; the 
whole length of the reservoir was 20 feet precisely, an addi- 
tional length of 7°3 inches having been reserved to form a gene- 
rating chamber in connexion with the reservoir. The dimen- 
sions of the reservoir are, 
Length of experimental reservoir . . . 20 feet 
Breadth of experimental reservoir . . . 1 foot. 
The bottom of the reservoir was placed with care in the hori- 
zontal plane, so that it could be filled and emptied conveniently. 
The reservoir is represented in Plate I., fig. 1. A is the trans- 
verse section, B and D are longitudinal sections of the levels of 
the reservoir. 
Method of determining the velocity—A channel of great 
length may appear at first sight more suitable to the determi- 
nation of velocity than the comparatively short one here em- 
ployed, whose whole length was traversed by some of the waves 
in less than five seconds; and it would have been preferable for 
that purpose had not the method of reflection been employed, 
by which all the advantages of that method when employed in 
the repeating circle and other instruments are obtained for the 
diminution of errors of observation, and by which also the pro- 
