^{page 42 note *} On this subject I beg to refer to my friend Mr Main's admirable memoir in the Transactions of the Astronomical Society, v. . It may be interesting to add the following remarks from a private communication of his to myself:—“At the time when I was requested to draw up a memoir on the subject of annual parallax, the amount of evidence of its sensible existence for any star whatever, which had even arisen from the discussion of investigations previous to Bessel's, was exceedingly small; and I believe that, at that time, any new attempt was likely to be received with the smile of incredulity, which repeated failures will always, in the long-run, tend to produce. No sensation was caused in England by the announcement of Bessel's investigation; and I remember that, to some astronomers, his confidence in the certainty of his result seemed far from warranted. At present there exists very little scepticism with respect to our knowledge of the parallax of 61 Cygni. But it was deduced by a method with which English astronomers were, I may assert, in general, unfamiliar, perhaps through the want of a good heliometer . . . . . It was an evidence of very creditable faith, therefore, which induced Mr Henderson, in default of other means, to attack this star rigorously by meridian observations in both elements, and this notwithstanding his accurate knowledge (for no man living excelled him in his knowledge of every thing that had been done in every department of modern practical astronomy, from its commencement) of that total failure of every attempt that had been made under the ablest astronomers of this country, in the northern hemisphere. And so fully was he impressed with the conviction of his ultimate success, that he left it as a legacy to his successor, who has sent over a very complete and beautiful series of observations, which, after their discussion by Mr Henderson himself, not long before his decease, has, in the minds of many, pretty nearly decided affirmatively the question of the existence of a considerable parallax.”