ON WAVES. 461 
From these observations it appears that the summit of the 
tide wave increases in height as it ascends the river. From 
station VII. to station VI. this increase amounts to about 
2 inches ; at station V. it amounts to 5°2 inches; at III. it has 
become 6°1 inches ; and at Glasgow 10:1 inches is the difference 
between the level of the wave of high water above that at Port 
Glasgow, 18°5 miles below. This difference varies slightly 
with the state of the tides, and with the condition of the current 
of fresh water in the river. At low water the surface of the 
river is higher at Glasgow than at Port Glasgow by 33 inches ; 
at station III. this difference is 27 inches, at IV. about 25 inches, 
and at V. about 12 inches. 
Difference of level at H. W. Difference of level at L. W. 
Station I. 10°1 inches. 33 inches. 
Station II. 9°1 inches. 31 inches. 
Station III. 7-0 inches. 27 inches. 
Station IV. 6°1 inches. 25 inches. 
Station V. 5°2 inches. 12 inches. 
Station VI. 2-2 inches. 5 inches. 
Station VII. 0:0 inches. O inches. 
The comparison of these numbers with the channel of the 
rivers in Plate VIII. will be interesting, as showing the influence 
of the form of the channel upon the height of the tide wave and 
the current of the river. 
Plate V. is a diagram showing the height of the tide wave 
as it reached the successive stations in various states of the 
wind. The waves are transposed so as to have a common 
origin, at station VIII. The effect of westerly winds in in- 
creasing the height of the wave, and of easterly winds in de- 
pressing it, is manifest. The wave of the 24th of April is 
curious in this respect, that whereas the wind had been west- 
erly, and changed, during the progress of the high water, to 
the east, so the wave which previously was higher, afterwards 
becomes lower than those adjacent to it; it therefore intersects 
them. The wind was in no case equivalent to what is con- 
‘sidered a gale or storm. 
Plate IV. represents the form of the tide wave as it passed 
the successive stations on the River and Frith of Clyde. 
A series of stars marks the centre of the wave, and has been 
placed there for the purpose of showing the dislocation of the 
wave, or the transposition of its higher parts forward, or the 
retardation of its lower parts by the shallowness of the water 
through which it has advanced. There is a remarkable re- 
version of this process in the wave of the Cumbray, Station IX., 
