418 SEVENTH REPORT—1837. 
likewise employed in the practical uses of every-day life, and 
took an important part in that commercial intercourse by means 
of which the comforts of life and the advancement of civilization 
are immediately promoted. It had been ascertained by former 
researches that the resistance of fluids to bodies moving through 
them is affected by an element which had not been formerly 
recognised ; that the new element which had given rise to con- 
tradictory and apparently anomalous phenomena was a wave 
produced in the fluid by the moving body; and that this wave 
affected the amount of resistance, either positively or negatively, 
according as the velocity of the wave was greater or less than 
that of the moving body*. It became, therefore, an inquiry of 
theoretical and general interest, as well as of special and prac- 
tical importance to the art of navigation, to determine with 
great accuracy the laws of this wave. It had already been 
satisfactorily established that the velocity of propagation of this 
wave was nearly that due to half the depth of the fluid, that 
this velocity was independent of the form of the generating 
solid, and of the generating velocity of the solid. But this 
law had not been extended to channels of different forms ; 
neither had the conditions necessary to the existence of this 
wave, nor the nature of the mechanism by which its propa- 
gation takes place, been described and ascertained. This wave 
had been called the great solitary wave of the fluid, but its re- 
lation to other waves, and its identity or diversity, had not been 
determined. 
It was also necessary to determine the nature and class of 
the waves with which we are most familiar, and which we see 
at the surface of water agitated by the wind, and which break 
on the shores of the sea. Do these belong to the previous 
class of waves, or do they not? their form and velocity have 
been thought to depend in some measure on the depth. Do 
they belong to the first class of waves, or are they a dif- 
ferent class ? 
But the most important of all these investigations, both in 
relation to the advancement of physical science and to the 
practical value of their results, are probably those which refer 
to the propagation of the tide. The recent researches of Mr. 
Lubbock and Mr. Whewell, carried on in connexion with this 
Association and by its assistance, have conferred on the subject 
of the tides the interest of novelty as well as scientific value. 
Their researches have gone far towards removing the stigma 
* Researches in Hydrodynamics, by John Scott Russell, Esq., M.A. F.R.S, 
Edinburgh, Phil. Trans, R.S.E., 1836. 
