The Solar Parallax

IF Mr. Proctor had printed in full my memoranda on the errors and imperfections of his history of the solar parallax, or if he had said nothing about it, I should have said nothing more in defence of my review. But, in NATURE of September 28, he gives so inadequate an account of my notes, hiding the point of the most remarkable of his inaccuracies, and ignoring the imperfections entirely, that I am compelled in self-defence to explain. In describing the various discussions of the Transit of Venus which preceded that of Mr. Stone, he says (p. 61) : `` Newcomb, of America, was more successful. He deduced the value 8'' 87 by a method altogether more satisfactory than Powalky's. But still the agreement between the different observations was not so satisfactory as could be wished, nor had Newcomb adopted any fixed rule for interpreting the observations of internal contact, which, as I have said, are affected by the peculiar distortion of Venus's disc at that moment.''