HOPKINS ON THE LAKE DISTRICT. 91 
had any material effect in the transport of blocks from the Lake 
district. 
The velocity of the current at any particular poimt of the sur- 
rounding sea would rapidly increase after the wave had reached that 
point and then decrease till the whole wave had passed by, after 
which the current would cease. If it acted on a block very much 
smaller than the greatest one it was capable of moving, it would 
communicate a considerable velocity to the block, which would then 
be made to accompany the wave to a considerable distance. If, on 
the contrary, the block should be nearly as large as the greatest one 
which the current with its maximum velocity could move, it would 
be only for a very short time that the current would be effective in 
moving the block, which would thus be transported only to a com- 
paratively small distance. Consequently the transport of large blocks 
to considerable distances would require many repetitions of the action 
of these currents, and therefore many distinct movements of eleva- 
tion, since each such movement would only produce its single wave 
of translation. Thus this theory becomes related to our theories of 
elevation, since it requires a succession of elevatory movements of a 
paroxysmal character ; and I may here add, that I believe such move- 
ments to be those by which we can best account for the general phe- 
nomena of elevation and denudation. 
22. To convey a distinct idea of the effectiveness of currents which 
may be produced in the manner here supposed, I will give a state- 
ment of certain calculated results, which may be taken as correct to 
a degree of approximation sufficient for our purpose. 
Depth of the Sea. | Height of the Wave. |Velocity of the Current. 
Feet. Feet Miles per Hour. 
Pm 20 63 
200 50 12 
1100 22 
25 53 
300 50 -103 
100 193 
25 5 
400 50 9 
100 17 
600 150 204 
800 200 28 
The depth of the sea here given is its depth independent of the 
wave; the height of the wave is the height of its crest, or highest 
point; and the velocity of the current is the maximum velocity, or 
that which exists under the crest of the wave. 
It will be observed that for the same depth the velocity of the 
curr nt is nearly proportional to the height of the wave; and also 
that for a given height of the wave the velocity of the current de- 
