collecting beetles he employed a labourer to "scrape the moss off old
trees in winter, and place it in a bag, and likewise to collect the
rubbish at the bottom of the barges in which reeds were brought from the
fens, and thus ... got some very rare species."

During the summer vacation of 1831, at the personal request of Henslow,
he accompanied Professor Sedgwick on a geological tour in North Wales.
In order, no doubt, to give him some independent experience, Sedgwick
sent Darwin on a line parallel with his own, telling him to bring back
specimens of the rocks and to mark the stratification on a map. In later
years Darwin was amazed to find how much both of them had failed to
observe, "yet these phenomena were so conspicuous that ... a house burnt
down by fire could not tell its story more plainly than did the valley
of Cwm Idwal."

This tour was the introduction to a momentous change in his life. On
returning to Shrewsbury he found a letter awaiting him which contained
the offer of a voyage in H.M.S. _Beagle_. But owing to several
objections raised by Dr. Darwin, he wrote and declined the offer; and if
it had not been for the immediate intervention of his uncle, Mr. Josiah
Wedgwood (to whose house he went the following day to begin the shooting
season), who took quite a different view of the proposition, the
"Journal of Researches during the Voyage of H.M.S. _Beagle_," by Charles
Darwin, would never have been written.

At length, however, after much preparation and many delays, the
_Beagle_ sailed from Plymouth on December 27th, 1831, and five years
elapsed before Darwin set foot again on English soil. The period,
therefore, in Darwin's life which we find covered by his term at
Edinburgh and Cambridge, until at the age of 22 he found himself