PROCEEDINGS OF THE SOCIETY. 379 



of the samo kind as prevented the discovery of the angle with a sine 

 greater than 1 ! 



What, therefore, Mr. Shadbolt could intend by the sentence that 

 " nothing had been shown to disprove his view," it was difficult to say, 

 not a single shred of his demonstration having been left standing, and 

 nothing remained but the words, " I have therefore demonstrated 

 beyond dispute," &c. ! 



(3) A remark must also be made as to the last sentence of 

 Mr. Shadbolt's note, in which he suggested that even if his view 

 of radiation turned out to be incorrect, it did not affect the dis- 

 cussion ! Now he (Mr. Crisp) had no desire to press unduly upon 

 Mr. Shadbolt personally, but it was obviously impossible, under 

 the special circumstances of the case, to allow that to pass. Mr. Shad- 

 bolt, having an unlimited range of selection, and being absolutely 

 free to choose his own ground, deliberately selected the photo- 

 metrical question on which to rest his claim to have " demon- 

 strated beyond dispute " that his view of the aperture question was 

 the correct one — a demonstration, which was not couched in the usual 

 style of scientific papers, but in regard to which a course was 

 adopted (happily exceptional in these days) of railing in advance at 

 the supposed absurdity of a scientific theory, admittedly without 

 having first made any endeavour to ascertain the grounds on which 

 it had been accepted — a paper, moreover, in which it had been 

 attempted to hold up to ridicule the editors of the Journal, and the 

 " authorities " of the Society, for their inability to understand the 

 extremely simple explanation which Mr, Shadbolt, in all seriousness, 

 supposed to dispose of the whole matter. 



When it turned out that it was not they but Mr. Shadbolt himself 

 who had overlooked (in fact was actually not aware of) the funda- 

 mental optical principle which upset his demonstration, he must not 

 simply turn round and suggest that it made no difference whether it 

 was right or wrong. If it was wrong, the editors and the "autho- 

 rities " were of course not so much to blame after all for not having 

 understood it or adopted it, and they were entitled to have that point 

 properly disposed of and not slurred over before passing to another. 



In the remarks which he (Mr. Crisp) had made, he need hardly 

 say that he was acting simply on the defensive, and was only con- 

 cerned in repelling, not on his own behalf, but in the interest of 

 the Society itself, the suggestion which Mr. Shadbolt had made of, 

 what he evidently honestly believed to be, a gross state of ignorance 

 on the part of the " authorities " of the Society. A merely tu quoque 

 retort "would be in every way out of place ; for at the time Avhen Mr. 

 Shadbolt was President — now twenty-five years ago — microscopical 

 optics was in its infancy. The Lambert-Bouguer law of radiation in 

 one and the same medium, though older than the century, had not 

 then been appreciated by microscopists — the principle of increased 

 radiation in denser media than air had no practical interest in micro- 

 scopy, as at that time immersion glasses had not found their way 

 into England — while, further, all microscopical optical problems 

 were treated, in accordance with the optical literature of the day, as 



