"Mar. 12th is the date of the Preface to my 1832 volume of Observations: it was of course distributed a few weeks later.--In my Report on Astronomy I had indicated the Mass of Jupiter as a subject requiring fresh investigation. During the last winter I had well employed the Equatoreal in observing elongations in R.A. of the 4th Satellite. To make these available it was necessary to work up the theory carefully, in which I discovered some remarkable errors of Laplace. Some of these, for verification, I submitted to Mr Lubbock, who entirely agreed with me. The date of my first calculations of the Mass of Jupiter is Mar. 1st: and shortly after that I gave an oral account of them to the Cambridge Philosophical Society. The date of my Paper for the Astronomical Society is April 12th. The result of my investigations (which was subsequently confirmed by Bessel) entirely removed the difficulty among Astronomers; and the mass which I obtained has ever since been received as the true one. "On Apr. 9th my wife's two sisters, Elizabeth and Georgiana Smith, came to stay with me.--On Apr. 22nd I began lectures, and finished on May 21st: there were 54 names. During the course of the lectures I communicated a Paper to the Philosophical Society 'On the calculation of Newton's experiments on Diffraction.'--I went to London on the Visitation of the Greenwich Observatory: the dinner had been much restricted, but was now made more open.--It had been arranged that the meeting of the British Association was to be held this year at Cambridge. I invited Sir David Brewster and Mr Herschel to lodge at the Observatory. The meeting lasted from June 24th to 30th. We gave one dinner, but had a breakfast party every day. I did not enter much into the scientific business of the meeting, except that I brought before the Committee the expediency of reducing the Greenwich Planetary Observations from 1750. They agreed to represent it to the Government, and a deputation was appointed (I among them) who were received by Lord Althorp on July 25th. On Aug. 3rd Herschel announced to me that _£500_ was granted.