156 Sir D. Brewster's Reply to the Astronomer Royal 



lionour. No doubts were expressed to me about the accuracy 

 of my experiments, and no explanations asked ; and being 

 accidentally in Edinburgh on the 6th of January, the reading 

 of the announcement at the meeting of the Royal Society that 

 evening was the principal intimation I received of the adjudica- 

 tion of the prize. Prof. Forbes, the Secretary to the Physical 

 Class, was then ihe representative of physical science in the 

 Council. I knew that he had made many experiments on the 

 action of absorbent media on the solar spectrum, and I have 

 no doubt that he observed the great fundamental fact described 

 by Sir John Herschel and myself, which, if a truth, settles the 

 question between Mr. Airy and me. 



It would appear that in the year 1833 Mr. Airy made experi- 

 ments on the spectrum. He could not see any change of 

 colour in the spectrum produced by absorbent media, and he 

 mentioned this result orally, and from recollection, at a 

 meeting of the Cambridge Philosophical Society. He did not 

 consider his experiments worthy of being preserved, for he did 

 not even copy them from his pencilled notes: he did not think 

 them deserving of publication ; and yet Dr. Whevvell, the 

 Historian of science, takes them \x^ J our years, afterwards, and 

 setting aside Sir John Herschel's experiments, which he may 

 not have known, and mine which he did know, and holding 

 cheap the decision of the Royal Society, of which he probably 

 was also ignorant, he adduces the experiments of Mr. Airy, 

 without mentioning his name, as hostile to mine, by stating 

 that my facts were "denied by other experimenters." 



This gratuitous challenge of the accuracy of my experiments, 

 on anonymous authority, was animadverted upon in one of the 

 reviews of Dr. Whewell's work ; and upon publishing a second 

 edition of it, he naturally applies to his anonymous experi- 

 menter, who turns out to be Mr. Airy. Without making a 

 single new experiment, without even having recourse to his 

 pencil notes, which he seems to have lost, the Astronomer Royal 

 authorizes the Master of Trinity to refer again to his experi- 

 ments as invalidating my analysis of solar light. Dr. Whewell 

 has of course done this; but he has done it in a note so ex- 

 ceptionable in its argument, and to me so unintelligible in its 

 interrogatories, that I am most unwilling to criticise it. He 

 asks me, for example, if it is meant, that is, if I mean, that 

 Newton's experiments prove nothing i Who ever said that 

 they proved nothing? Nevvton's/'?75OTCf//c analysis of the spec- 

 trum is, in my opinion, one of the greatest of his discoveries. 

 "Or," he adds, " is Newton's conclusion allowed to be true of 

 light which has not been analysed by absorption ?" To this 

 I reply, that Newton's conclusions respecting the apparent 



