ce in
the beds of the great oceans. I wish that some doubly rich millionaire
would take it into his head to have borings made in some of the Pacific
and Indian atolls, and bring home cores for slicing from a depth of 500
or 600 feet. (535/4. In 1891 a Committee of the British Association was
formed for the investigation of an atoll by means of boring. The Royal
Society took up the scheme, and an expedition was sent to Funafuti, with
Prof. Sollas as leader. Another expedition left Sydney in 1897 under the
direction of Prof. Edgeworth David, and a deeper boring was made. The
Reports will be published in the "Philosophical Transactions," and will
contain Prof. David's notes upon the boring and the island generally,
Dr. Hinde's description of the microscopic structure of the cores and
other examinations of them, carried on at the Royal College of Science,
South Kensington. The boring reached a depth of 1114 feet; the cores
were found to consist entirely of reef-forming corals in situ and in
fragments, with foraminifera and calcareous algae; at the bottom there
were no traces of any other kind of rock. It seems, therefore, to us,
that unless it can be proved that reef-building corals began their work
at depths of at least 180 fathoms--far below that hitherto assigned--the
result gives the strongest support to Darwin's theory of subsidence; the
test which Darwin wished to be applied has been fairly tried, and the
verdict is entirely in his favour.)

2.IX.V. CLEAVAGE AND FOLIATION, 1846-1856.

LETTER 536. TO D. SHARPE.

(536/1. The following eight letters were written at a time when the
subjects of cleavage and foliation were already occupying the minds of
several geologists, including Sharpe, Sorby, Rogers, Haughton, Phillips,
and Tyndall. The paper by Sharpe referred to was published in 1847
("Quart. Journ. Geol. Soc." Volume III.), and his ideas were amplified
in two later papers (ibid., Volume V., 1849, and "Phil. Trans." 1852).
Darwin's own views, based on his observations during the "Beagle"
expedition, had appeared in Chapter XIII. of "South America" (1846) and
in the "Manual of Scientific Enquiry" (1849), but are perhaps nowhere
so clearly expressed as in this correspondence. His most important
contribution to the question was in establishing the fact that foliation
is often a part of the same process as cleavage, and is in nowise
necessarily connected with planes of stratification. Herein he was
opposed to Lyel