“I have the attendance-bills of my Lectures to Senior Sophs (16) from Feb. 3rd to Feb. 23rd, and to Freshmen (40) from Feb. 27th to Mar. 15.  It would appear that I gave but one college-lecture per day (my belief was that I always had two).  The tutor’s stipend per term was L50.  On my quires I find, Investigations for the ellipticity of a heterogeneous spheroid when the density is expressed by sin qc/_qc_ (the remarkable properties of which I believe I discovered entirely myself, although they had been discovered by other persons), Theoretical Numbers for precession, nutation, &c., some investigations using Laplace’s Y, hard work on the Figure of the Earth to the 2nd order,’Woodhouse’s remaining apparatus,’ Notes about Lambton’s and Kater’s errors, Depolarization, Notes of Papers on depolarization in the Phil.  Trans., Magnetic Investigations for Lieut.  Foster, Isochronous Oscillations in a resisting medium, Observations on a strange piece of Iceland Spar.  On Mar. 7th forwarded Preface and Title Page for my Mathematical Tracts.

“Some time in this term I began to think of the possibility of observing the diminution of gravity in a deep mine, and communicated with Whewell, who was disposed to join in experiments.  My first notion was simply to try the rate of a clock, and the Ecton mine was first thought of.  I made enquiries about the Ecton mine through Mr Smith (of Edensor), and visited the mine, but in the meantime Whewell had made enquiries in London and found (principally from Dr Paris) that the mine of Dolcoath near Camborne in Cornwall would be a better place for the experiment.  Dr Paris wrote to me repeatedly, and ultimately we resolved on trying it there.  In my papers on Mar. 21st are various investigations about attractions in both mines.  On Apr. 3rd I went to London, principally to arrange about Dolcoath, and during April and May I was engaged in correspondence with Sir H. Davy (President of the Royal Society), Mr Herschel, and Dr Young (Secretary of the Board of Longitude) about the loan of instruments and pendulums.  On Apr. 23rd I was practising pendulum-observations (by coincidence); and about this time repeatedly practised transits with a small instrument lent by Mr Sheepshanks (with whom my acquaintance must have begun no long time before) which was erected under a tent in the Fellows’ Walks.  On my quires I find various schemes for graduating thermometers for pendulum experiments.

“I find also Notes of examination of my brother William, who had come to College last October; and a great deal of correspondence with my mother and sister and Mr Case, a lawyer, about a troublesome business with Mr Cropley, an old friend of G. Biddell, to whom my father had lent L500 and whose affairs were in Chancery.