140 CORRESPONDING SOCIETIES.
together with silicate of alumina and combined water, and minute quantities
of other materials. The best account of these marine nodules with drawings
occurs in M. J. Thoulet's Oceanographic, 1890.
Both in appearance and composition it is clear that the nodules described
by Miss Thresh have the closest resemblance to these marine nodules. This
suggests a common origin and that the former were not formed in situ, but
that during the ice age they were picked up by floating icebergs from the sea
bottom along with other material and transported to and deposited in their
present position. This being so, their occurrence in the Boulder-clay and not
in the London-clay soils is owing, not to the necessity of chalk for their produc-
tion as suggested by Miss Thresh, but to the fact that the Boulder-clay is a
glacial deposit and the London-clay is not.
The explanation given by Miss Thresh of the formation of the nodules is
that which has been advanced by Dieulafait (Comptes Rendus, 1883, p. 718)
for those of marine origin, who states that solution of manganese carbonate
exists in sea water and that this is attacked by the dissolved oxygen with
liberation of carbonic acid gas and deposition of manganese peroxide.
The importance of the matter lies in the fact that if the nodules are of
marine origin, valuable light is thus thrown upon the source of the Boulder-
clay in which they occur.
T. S. DYMOND.
[County Technical Laboratories, Chelmsford, December, 1901.]
THE CORRESPONDING SOCIETIES COM-
MITTEE OF THE BRITISH ASSOCIATION,
GLASGOW, 1901.
REPORT OF THE CLUB'S DELEGATE,
F. W. RUDLER, F.G.S., Chairman of the Conference.
The Lecture Theatre of Medical Jurisprudence, in the
University Buildings, was placed at the disposal of the
Delegates throughout the Association week. Two meetings of
the Delegates were held here—one on Thursday, Sept. 12th, and
the other on Tuesday, Sept. 17th. The Chairman at these Con-
ferences was the delegate of the Essex Field Club, Mr. F. W.
Rudler; the Vice-Chairman was Mr. W. Whitaker, F.R.S., and
the Secretaries were Dr. J. G. Garson and Mr. A. Somerville.
The meetings were well supported, no fewer than 42 societies
having sent delegates.
The Chairman opened the proceedings with an informal
address, in which he suggested the local societies should regard it
as part of their duty to seek, register, and record in a systematic