76 PETER GUTHRIE TAIT 



ments on Radiation at various pressures of the surrounding gas, Brebner's work 

 on electrolysis, and Meik and Murray's investigations on the effect of load 

 on the resistance of copper wires. 



Robertson Smith also found time for an exposure of Hegel's attack upon 

 the principles of the calculus as laid down in Newton's Principia, a kind of 

 criticism for which Smith, by virtue of his profound knowledge of both 

 mathematics and metaphysics, was singularly well equipped. 



During the early years of his professoriate, Tait was on intimate terms 

 of friendship with W. H. Fox Talbot, best known for his discoveries in 

 photography and his deciphering of the cuneiform inscriptions. Fox Talbot 

 was a mathematician of distinct originality and was keenly interested in 

 experimental physics. He lived a good deal in Edinburgh during the sixties 

 and early seventies ; and on Saturday forenoons he often paid Tait a visit at the 

 College to experiment in light and magnetism. On May 15, 1871, Fox Talbot 

 communicated three short papers to the Royal Society of Edinburgh, the first 

 of which, "Note on the early History of Spectrum Analysis," was probably 

 suggested by Tait's address on that subject delivered the same evening before 

 the Society. The second, " On a New Mode of observing certain Spectra," 

 ends with the remark that "all these experiments were made in the Physical 

 Laboratory of the University of Edinburgh by the kind permission and 

 assistance of Professor Tait." The third, " On the Nicol Prism," recalls some 

 of his earlier investigations and contains the description of a modified form of 

 polarising prism, which is made half of calc spar and half of glass. I have 

 often heard Tait express the very high opinion he held in regard to Fox 

 Talbot, whose discovery of anomalous dispersion was kept back from the 

 world by his own modesty and the too great caution of Sir David Brewster, 

 and had to be rediscovered many years afterwards by Le Roux and Christian- 

 sen. 



The following letter touches on several points of interest. 



17 DRUMMOND PLACE, 



EDINBURGH, 11/1/71. 

 My dear Andrews, 



We all heartily join in wishing you and yours many happy new years. 

 We are all well, but very busy I at Physics, the rest at skating\ Even my wife has 

 become an enthusiast. 23 years ago I was wild about it, but I feel no inclination 

 to waste time on it now.... 



I am delighted to hear that you are getting on so well with your high pressures. 

 I often wish I were back again in Belfast. True I had more lecturing to do, and 



