or ey ae 
he ee tt i ga ee ld 
ON WAVES. 421 
in part of its channel, tolerably regular, having been formed 
artificially through a considerable part of its length; it was 
thought likely to answer the purpose. 
In the month of September Mr. Russell visited Cheshire for 
the purpose of instituting the observations. He found the 
river more perfectly suitable than could have been anticipated. 
For more than five miles the channel of the river is perfectly 
straight, of a depth and width nearly uniform, inclosed between 
banks that are even and well kept, and that have everywhere 
the same slope, while the bottom has the slight declivity of 10 
inches per mile. Along this channel the tide rolls with a mo- 
derate velocity, sometimes marked by a crested surge, and 
sometimes commencing by a motion hardly perceptible, and 
here it is inclosed by banks so high as to protect the wave most 
perfectly from the action of the wind from every point ex- 
cept two. 
The channel of the river was measured and sounded with 
great care, and observations of its tidal wave will be found in 
this report. The form of the tide wave is given in plate (VI.). 
The observations on the Dee having furnished data for the 
determination of the law of the propagation of the tidal wave 
in a given regular channel, it was only necessary further to as- 
certain the nature of its motion in a channel of a less regular 
form, and to determine the effect of the wind upon it. But the 
difficulty in this case was enhanced by the circumstance that a 
most minute and expensive survey would be required to deter- 
mine the figure of such a channel with the accuracy necessary 
to furnish data for calculation. In this however the Committee 
were again fortunate. The River and Frith of Clyde on the 
West of Scotland presents along and varied tidal channel which 
has all the variety of form necessary for such an investigation. 
The navigation of this river is under the management of a Board 
of Trustees, under whose superintendence it has been greatly im- 
proved, and who have been at great pains to determine its con- 
dition by very careful surveys. To that Board your Committee 
made application, and having the kind assistance of Sir Thomas 
Brisbane, who, as a former President of the Association, took 
a deep interest in forwarding its views, they succeeded in ob- 
taining the effective cooperation of the Board of Trustees of the 
Clyde in carrying on an investigation which they considered of 
much importance to the navigation and future improvement of 
their own river.* Their excellent engineer, Mr. Logan, was 
immediately placed in communication with Mr. Russell, :and 
* The thanks of the British Association were afterwards tendered to the 
Trustees of the Clyde for their liberality. 
