APPENDIX A XLVII 



the book a huge mathematical blunder in calculating the attraction of 

 two spheres, very properly reported his discovery to the mathematical 

 and physical section, and created a very lively discussion. 



By good fortune) I had both books in my possession, the English 

 "System of the World," dated 1731, and the Latia Pciaaipia; ' in the 

 standard edition of the present day. This proved that the former was 

 no ipart of the j Briucipia, and the enormity of the blunder settled the 

 question about genuineness raised in the Encyclopaedia. Newton could 

 not have made it. It was of the same character as that sometimes made 

 by a school boy at an examination, when he calculates that the interest 

 on $300 for 6 months at 6 per cent is about $72,000. 



I may add as exemplifying that science is independent of nationality, 

 dihat the] standard edition spoken of, was a reprint of the edition pub- 

 lished about twelve years after Newton's death, with a commentary, also 

 in Latin, by two Frenchmen, PP. Le Sueur and Jacquier, priests of the 

 Gallican order of Minims, that it was edited by them at Rome, and 

 dedicated to a French Cardinal, Eohan. 



The second instance occurred at the same meeting and was more in- 

 teresting. For about thirty years previously English text-books on 

 optics had been stating and even lamenting, especially after the inven- 

 tion of the spectroscope, that Newton had never used the slit instead of 

 the round hole for the admission of light on the prism in the formation 

 of the spectrum. I happened to have a. copy of Newton's "Opticks" and 

 knew tL-at the statement was wrong. He mentions very particularly the 

 sdvantages of the slit. But I was afraid to write aboul the error. For, 

 surely, I thought, there must be many eminent men of science in Eng- 

 land who know of it, and if they think it unnecessary to make a correc- 

 tion why should I interfere? It cannot be so common as it appears 

 to be. 



The late Dr. Rowland, of Johns Hopkins' University happened to be 

 exhibiting his concave gratings with their beautiful effects in the resolu- 

 tion of the spectrum, when a (prominent scientific man, after prolonged 

 inspection, expressed the usual regret about Newton. After that, 1 

 immediately wrote a short note to a weekly scientific magazine; but with 

 no result apparently. I subsequently repeated Newton's experiments 

 in Newton's manner exactly, and submitted a paper thereon to this 

 Society showing that it was absolutely impossible to avoid seeing the dark 

 lines, although Newton makes no mention of them. In books published 

 since that time the statement has been given correctly. 



Why Newton didn't see the lines may be explained either by the fact 

 that he trusted to an assistant of whom he speaks or that the quality of 

 his glass was bad, possibly obstructing somewhat the passage of the light, 



