of Edinburgh, Session 1885-86. 
795 
water increases uniformly with time, so that the curves of vertical 
distribution for successive half-hourly periods are parallel to each 
other. This indicates a movement of water en masse from the upper 
to the lower parts of the estuary. 
From three and a half to five hours ebb the temperature of the 
bottom water does not increase much, but between 1\ and 3 fathoms 
from the bottom there is a continuous rise of temperature, which 
becomes less marked near the surface. The curves show a shearing 
displacement during this period, and appear to indicate that the 
current at the bottom is slackened, and that the upper and middle 
layers of water flow on over it. 
During the last hour of ebb the bottom water gradually but 
distinctly cools, and the fall of temperature is shared in by the 
lower fathom and a half ; the next fathom shows a gradual rise in 
temperature, while the surface layers remain nearly unaltered. The 
water on the bottom appears to be flowing, while that on the surface 
is still ebbing. Ships anchored in the channel begin to swing, and 
turn completely round, from half an hour to twenty minutes before 
boats anchored in a similar position are moved, a fact which 
proves conclusively that flood tide sets in first at the bottom. 
Ebb tide at Kincardine is illustrated by the curves in Plate 
XXVIII. fig. 3. 
Ebb Tide. — Alloa: depth from 3J to 1 fathom. The difference 
of temperature (and of salinity also) between surface and bottom 
is here so slight that it is difficult to determine the exact vertical 
distribution. Speaking generally, the curves move along the scale 
nearly parallel to themselves, showing a movement of translation in 
the water from the upper part of the estuary firth wards; there are 
indications, but too slight to be held as altogether satisfactory, that 
a certain amount of shearing motion takes place as at Kincardine 
just before the turn of the tide (see Plate XXVIII. fig. 6). 
Flood Tide. — Kincardine: depth from 3 to 5 fathoms. During 
the two first hours of flood the whole body of water from surface 
to bottom falls in temperature uniformly, the curve of vertical 
distribution showing an inflection in the second fathom from 
the bottom. This indicates a flowing up-stream of the whole 
water. An upward travelling of the inflection along the curve 
shows that the actual increase of depth is due not to the damming 
