232 
THE REV. W. WHEWELL ON THE PROGRESS OF THE 
Second Series . — I now proceed to consider another series of places taken on the 
coasts of the British Channel, namely, Ferrol, Brest, Cherbourg, Havre, on the con- 
tinental coast, and Penzance, Plymouth, Bridport, Lulworth and Portsmouth on our 
own shores. 
As before, comparing the diurnal with the semidiurnal wave, we find that 
At Ferrol, the diurnal wave is 2f hours earlier. 
At Brest, 3|- hours earlier. 
At Penzance, 2% hours earlier. 
At Plymouth, 2\ hours earlier. 
At Cherbourg, 4 hours earlier. 
At Havre, 3 hours earlier. 
So far the two waves appear to go on nearly with the same velocity ; but the Isle 
of Wight appears to produce a disturbance. 
For proceeding onwards, we find that 
At Bridport, the diurnal wave coincides with the semidiurnal. 
At Lulworth, the diurnal wave is five hours later. 
At Portsmouth, it is 4^ hours later. 
It appears, therefore, that at this point, where St. Alban’s Head and the Isle of 
Wight interpose themselves in its course, the diurnal wave receives a check which 
almost reverses its position, and makes the inequalities very different at places be- 
fore and after that point. Nor does this assertion rest upon any arbitrary mode of 
combining the facts, but it appears in the facts themselves. For instance, if we com- 
pare the high waters at Plymouth, and at Lepe, near Southampton, we shall find 
that their relation is contrary, the morning high waters being lower than the mean, 
and the evening high waters higher than the mean, from June 14 to 18 at Plymouth, 
and the same being the case at Lepe ; although the morning tide of one place is 
identical with the evening tide of the other. 
We may observe, that we have here a new proof of that, of which the recent ex- 
amination of the tides has supplied many proofs, that we can by no means reason 
on the supposition that the waters of the ocean approximate to a level surface, or 
that an elevation at one place is necessarily shared by the surrounding seas. We 
may also observe, that the part of the Channel where the diurnal wave is thus held 
back, had already been found to be marked by peculiar tidal features ; the cotidal 
lines turning round the promontories above mentioned as a kind of hinges, in con- 
sequence of the slow progress of the tide-wave near the shore. It is probable that 
the peculiarities which we thus discover to coexist in the motion of the diurnal and 
of the semidiurnal wave would be found to be connected, if we could analyse the 
hydrodynamical laws of the ocean. 
The motion of the diurnal wave being thus irregular, we can account for the 
variety of values of the diurnal inequality at different places. We can also conceive 
this wave to move in a manner even more irregular than we have yet described ; and 
