1911-12.] Obituary Notices. 497 
“ This method required two things : in the first place , the abandonment 
of the traditional practice of occupying, as it were, isolated points in the 
terrain to be conquered by science, from which isolated forays or raids 
were conducted under the guise of problem-solving and other virtuosities. 
Henceforth the pupil was to be conducted by an orderly series of reasonings 
up a sort of inclined plane from one well-defined conception to another, to 
the higher levels of the science — morphology, in the words of Sylvester, 
was to be introduced into algebra and mathematical analysis in general. 
“ Secondly : even in its elementary stages the science of algebra required 
setting in order, and the morphological method required a new, a precise, 
and to some minds a £ forbidding ’ terminology. This was the ‘ raising of 
the standard ’ playfully and ruefully described by Mr J. M. Barrie in 
An Edinburgh Eleven” 
All who had any acquaintance with Chrystal’s work will endorse these 
impressions, which spring from a sympathetic intercourse between a father 
and a son who had many intellectual interests in common, save perhaps 
that of mathematics. It is interesting in this connection to establish a 
correspondence between Chrystal and his great colleague, Peter Guthrie 
Tait. Tait was one of the examiners when Chrystal took his degree at 
Cambridge. The similarity of their mental gifts was brought out by the 
fact, often referred to by Tait, that Chrystal was distinctly the best 
candidate from Tait’s standpoint. Tait used to say that Chrystal easily 
outdistanced the other Wranglers on the problems which demanded real 
thought ! Another link between Tait and Chrystal was the preparation of 
the second edition of Thomson and Tait’s Natural Philosophy , vol. i., the 
proofs of Part I. having been read by Chrystal and Burnside. Chrystal’s 
appointment to the Edinburgh chair was hailed with intense delight by 
Tait, who knew he had gained a colleague who could think in physical 
lines. The full facilities he offered Chrystal to work in the laboratory 
have been already referred to. Each had for the other the greatest 
admiration, and much mutual help was given before their communications 
took final form in the printed page of the Royal Society Proceedings. In 
mathematics, and especially in geometry, Tait’s was, no doubt, the more 
original mind ; but Chrystal’s knowledge of recent developments was 
wider, and probably he had a juster view of the perspective of things. 
Tait revelled in the direct and powerful methods of quaternions ; but 
Chrystal used to say that it was Tait the man, and not quaternions the 
method, which was the real factor in any investigation which Tait made. 
Chrystal took a passing interest in Hamilton’s calculus during his early 
years at Edinburgh, and gave a course of lectures on vector methods. But 
vol. xxxii. 32 
