An unhappy fatality seems to hang over the publication of this Volume. Not many days after the concluding note to the Preface of this Edition was printed the Author went out of College; but he returned about a week afterwards, for the express purpose of passing the following Supplement to the Appendix through the Press, during the Christmas vacation; for he was anxious that the Volume should be out by the beginning of the Lent Term. But very soon after his return he met with a painful and dangerous accident, which for five months made him unfit for any continued intellectual labour: and he now resumes his task, though still crippled in his right arm, and anxious on many accounts to make the following supplementary Notes as short as he can without obscuring their meaning.

No. I.

Additional Remarks on the Nebular Hypothesis.

(p. ix, and p. xxi.)

It may have appeared strange to the reader of note D, that no allusion is made in it to The Telescopic Survey of the whole surface of the visible Heavens, by Sir John Herschel. The note was, however, printed several months before the first appearance of that great work. Supra. p. cccxxxiii., and note to p. ccccxli.

On reconsidering note D, I find that I have expressed myself inaccurately in referring to the ecliptic as if it were La Place's invariable plane of the Solar System.