236 ON THE SALINITY OF THE SEA WATER.
particular years is, of course, easily explained by greater
evaporation and smaller rainfall.
I have observed similar facts at Paglesham and West
Mersea, but not in Brightlingsea Harbour and the adjoining
creeks, or in Harwich Harbour and up the Stour.
It thus appears that, at all events in the summer of certain
years, the water in some of the Essex estuaries is even more
salt than the water outside coming in with the high tide.
Along the coast of Essex in summer the sea-water is also
somewhat more dense than that of the contiguous part of the
North Sea.
The following table shows the mean densities of the water in
summer off the coast, and at high and low water in the estuaries,
and the differences, plus or minus, of the low water compared
with the high, As will be seen, these differences, though not
great, are well marked. It will also be observed that, at all
events in summer, the water in the estuaries would be very
suitable for the purposes of salt-making by evaporation.
N.B.—All these numbers refer to the excess of density above
rain water, reckoned as 1000. Thus, in the case of the first item
in the above list, I give 26.37 instead of 1026.37, which shows
the effect of the salts more distinctly, independent of the weight
of the water.