ogical Society "On the
dust which falls on vessels in the Atlantic, and On the Geology of the
Falkland Islands"; in 1848 he contributed a note on the transport of
boulders from lower to higher levels; and in 1862 another note on the
thickness of the Pampean formation, as shown by recent borings at Buenos
Ayres. An account of the "British Fossil Lepadidae" read in 1850, was
withdrawn by him.

At the end of 1836 Darwin had settled himself in lodgings in Fitzwilliam
Street, Cambridge, and devoted three months to the work of unpacking his
specimens and studying his collection of rocks. The pencilled notes on
the Manuscript Catalogue in the Sedgwick Museum enable us to realise
his mode of work, and the diligence with which it was carried on. The
letters M and H, indicate the assistance he received from time to
time from Professor Miller, the crystallographer, and from his friend
Henslow. Miller not only measured many of the crystals submitted to him,
but evidently taught Darwin to use the reflecting goniometer himself
with considerable success. The "book of measurements" in which the
records were kept, appears to have been lost, but the pencilled notes
in the catalogue show how thoroughly the work was done. The letter R
attached to some of the numbers in the catalogue evidently refers to the
fact that they were submitted to Mr Trenham Reeks (who analysed some of
his specimens) at the Geological Survey quarters in Craig's Court. This
was at a later date when Darwin was writing the "Volcanic Islands" and
"South America".

It was about the month of March, 1837, that Darwin completed this work
upon his rocks, and also the unpacking and distribution of his fossil
bones and other specimens. We have seen that November, 1832, must
certainly be regarded as the date when he FIRST realised the important
fact that the fossil mammals of the Pampean formation were all closely
related to the existing forms in South America; while October, 1835,
was, as undoubtedly, the date when the study of the birds and other
forms of life in the several islands of the Galapagos Islands gave
him his SECOND impulse towards abandoning the prevalent view of the
immutability of species. When then in his pocket-book for 1837 Darwin
wrote the often quoted passage: "In July opened first note-book on
Transmutation of Species. Had been greatly struck from about the month
of previous March on character of South American fossils, and species on
Galapagos Archipel