ON THE SALINITY OF THE SEA-WATER. 235
*H. triquetrum Br. and Schimp.
On Forest, very common (2) !; Loughton (2) !; Epping
Forest (11) !; nr. Chelmsford (7); N. Essex (14);
Chalkney Wood, Earls Colne (8) !; Saffron Walden (9).
[The Club is greatly indebted to Mr. Chittenden, not
only for collating the information concerning the Museum
Herbaria of Mosses, and identifying doubtful examples, but also
for actually mounting and arranging the specimens. Mr.
Chittenden's work in this way has been of the highest Museum
value and a great aid to the Curator.—Ed.]
ON THE SALINITY OF THE SEA-WATER
ALONG THE COAST OF ESSEX.
By H. C. SORBY, LL.D., F.R.S., F.L.S., F.G.S., &c.
[Read October 27th, 1906.]
FOR a number of years (1884 to 1888, both inclusive)
I systematically studied the salinity of the water along
the coast and in the estuaries of Essex, and found that
one of the most important facts in connection with the
distribution of the marine animals was the difference between
the density of the high and low water. My results, however,
apply only to the summer months, from the early part of May
to the latter end of September; and no doubt they differ widely
from the conditions in winter. The comparative salinity was
determined by a hygrometer, which was far the most convenient
method on board a yacht.
What struck me much was that in some years at Burnham
on-Crouch the density of the low water was greater than at high
water ; and, in passing up the river to Battles Bridge, the
density became greater and greater. To my surprise I found
the well-marked Alga, Chorda, growing in some quantity not
much below Battles Bridge in 1885, when the density of the
water was very high, but I looked for it in vain in 1885, when
the density was much lower. I do not remember seeing it
elsewhere along the coast of Essex. This excess in density in