122
NOTES.
alkaline development and before fixing. This process is now obsolete
but it has its historical interest as being the outcome of a theoretical
discussion.
The value of Col. Russell's introduction of alkaline develop-
ment in 1862 does not, however, end with his own application of
the process to the dry plates then in vogue. The germ of the
discovery which has revolutionized modern photography was in
existence in 1864, when Bolton and Sayce made known their
collodion emulsion process, which was followed up by many
workers, and culminated in the introduction of gelatino-bromide
emulsion by Dr. Maddox in 1871. From that time emulsion pro-
cesses have steadily been gaining favour, and now are almost
exclusively in use. From the very beginning of their history, in
1864, these processes had therefore the benefit of Russell's method
of alkaline development, by which, or by some analogous plan,
such as the ferrous oxalate developer, are they only workable. It
will thus be seen that the influence of our late member's work
makes itself felt, as was stated previously, at the present time.
Whether Col. Russell continued his photographic work in later
times I have not been able to ascertain, but his name does not
occur among the more recent investigators in this department of
applied science. It is possible that the few years during which he
occupied himself with photography represented but a passing phase
of the many-sided pursuits to which he was attached. That he has
left a permanent mark in this field will be gathered from the present
sketch, and the genial naturalist and ardent sportsman must cer-
tainly take rank among Essex worthies as an original investigator
in a department of science widely remote from those other pursuits
by which he is perhaps more generally known to the members of
the Essex Field Club.
Seal in the Blackwater.—On July 9th we saw a seal in this river. It was ob
the south shore of Pont, in South Hope, between Robertson's and Bradwell Creeks.
We cruised about, and saw it rise six or seven times ; twice we got within a hun-
dred yards of it. The few seals that have occurred here have mostly appeared
later in the year.—Edward A. Fitch, Maldon.
Colias hyale and C. edusa at Maldon and Hazeleigh.—On Thursday,
29th August, I saw one specimen of Colias hyale at Maldon, and another at
Hazeleigh, on the Rectory hill, quite three miles distant from the first. I have
not met with this butterfly alive since June, 1877 (see Entom : x, 191). I also
saw a clouded yellow butterfly (C. edusa, L.) here, when shooting, on September
10th.—E. A. Fitch, Maldon.