“The Lectures as begun in 1827 included ordinary Mechanics, ordinary Hydrostatics and Pneumatics (I think that I did not touch, or touched very lightly, on the subjects connected with the Hydraulic Ram), and ordinary Optics (with a very few words on Polarization and Depolarization).  In 1828 the two first were generally improved, and for the third (Optics) I introduced a few words on Circular Polarization.  I believe that it was in 1829 that I made an addition to the Syllabus with a small engraving, shewing the interference of light in the best practical experiment (that of the flat prism); and I went thoroughly into the main points of the Undulatory Theory, interference, diffraction, &c.  In 1830 I believe I went (in addition to what is mentioned above) into Polarization and Depolarization of all kinds.  My best lecture diagrams were drawn and painted by my wife.  The Lectures were universally pronounced to be valuable.  The subjects underwent no material change in 1831, 2, 3, 4, 5; and I believe it was a matter of sincere regret to many persons that my removal to Greenwich terminated the series.  Each lecture nominally occupied an hour.  But I always encouraged students to stop and talk with me; and this supplement was usually considered a valuable part of the lecture.  Practically the lecture, on most days, occupied two hours.  I enjoyed the Lectures much:  yet I felt that the labour (in addition to other work) made an impression on my strength, and I became at length desirous of terminating them.

“The Observatory, when I took charge of it, had only one instrument—­the Transit-Instrument The principles however which I laid down for my own direction were adapted to the expected complete equipment, Planets (totally neglected at Greenwich) were to be observed.  Observations were to be reduced completely, and the reductions were to be exhibited in an orderly way:  this was a novelty in Astronomy.  I considered it so important that I actually proposed to omit in my publication the original observations, but was dissuaded by Herschel and others.  I sometimes suspended, observations for a short time, in order to obtain leisure for; the reductions.  I had at first no intention of correcting the places of the fundamental stars as settled at Greenwich.  But I found myself compelled to do so, because they were not sufficiently accurate; and then I took the course of observing and reducing as an independent observer, without reference to any other observatory.  I introduced the principle of not correcting instrumental errors, but measuring them and applying numerical corrections.  I determined my longitude by chronometers, and my latitude by a repeating circle borrowed from Mr Sheepshanks, which I used so well that the result; was only half a second in error.  The form of my reductions in the published volume for 1828 is rather irregular, but the matter is good:  it soon attracted attention.  In 1829 the process was much the same:  I had an assistant, Mr Baldrey.  In 1830 still