Obituary Notices. 
491 
1911-12.] 
meter,” “ Mathematics,” ‘‘Parallels,” “Perpetual Motion ” ; and the biographies 
of J. von Lamont, Mascheroni, Michell, Montucla, R. Murphy, Musschenbroek, 
Oughtred, Pascal (part), G. Peacock, Pell, Pfaff, Playfair, Pliicker, Poggen- 
dorf, Poisson, Recorde, Rheticus, Riemann, Robins, Sturm. Of these, “Pascal” 
and “ Poisson ” are of particular interest. 
“ Mathematics ” is a brief exposition of the historical development of 
the fundamental ideas of the various branches of the science, and in 
“ Parallels ” there is a clear account of the rise of non-Euclidian geometry. 
An address on this subject was given by Chrystal before the Royal Society 
of Edinburgh during his first year here — indeed, before he was formally 
elected a Fellow. In the same year he contributed along with Professor 
Tait an obituary notice of Professor Kelland, his predecessor in the Edin- 
burgh chair. A peculiar interest attaches to this obituary notice, inasmuch 
as Chrystal gives in it a remarkably appreciative account of Kelland’s 
investigations in wave motion — a subject which, towards the close of his 
own life, Chrystal was destined still further to elucidate in his masterly 
papers on seiches. 
An important part of the scientific labours of a Scottish University 
Professor of Mathematics is the practical work of teaching. When Chrystal 
came to Edinburgh every Arts student had to study mathematics as one of 
the seven compulsory subjects. There were no options. These conditions 
were not conducive to a high standard in mathematical study ; but even in 
these early days many a man of classical or philosophical attainments 
trembled as he entered the examination hall and sat down to tackle the 
algebra or the Euclidean geometry paper. The first year of Chrystal’s 
professoriate struck terror to the hearts of those unfortunates to whom the 
pons asinorum was a bridge of sighs. Keen, rapid, logical, full of sugges- 
tions as to wider realms of mathematical delights, Chrystal transformed the 
whole atmosphere of the class-room. “ Principles,” “ symmetry,” “ form ” — 
not an endless wrestling with examples — were his watchwords ; yet his exer- 
cises were splendid training. Eagerly the mathematical minds followed 
his fascinating lead ; despondingly and despairingly those not so gifted fell 
hopelessly behind, perceiving faintly, if at all, the finely knit sequence of 
ideas which formed the thread of his discussions. Nevertheless, when the 
time of testing came, the really intelligent, hard-working student got full 
credit for his limited mathematical powers ; for, with all his strenuous and 
successful labours to raise the standard of mathematical teaching, Chrystal 
was essentially just. With the close of the winter session of 1879-80 the 
University and Academic world of Edinburgh knew that a fresh force had 
come into their midst. 
