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literature, and bis elegance of taste and reach of illustration were 
of much service in adding to the attraction of his prelections, as well 
as giving a great charm to his conversation, and to his literary pro- 
ductions. His published works and contributions to periodical 
literature are too well known to require detailed notice. Those 
which related to scientific subjects were distinguished by a minute- 
ness of research and a precision of statement which give them a 
very great value, and which could hardly have been expected in one 
who was able at the same time to embellish them with so many 
beauties derived from his ample stores of imagination and fancy. 
His “ Treatise on Colour Blindness ” is a remarkable example of 
the exhaustive and practical manner in which he could treat such 
a subject; and his Lives of Scientific Men, while laudably com- 
pressed into a narrow compass, as compared with most modern 
biographies, are pregnant with valuable information and important 
results. He was in every way admirably qualified to diffuse among 
a wide circle of hearers and readers a strong interest in science as 
intimately connected with art and ordinary life. 
In the spring of 1855 he was appointed Director of the Industrial 
Museum, a situation for which he was eminently suited ; and in the 
autumn of the same year he was appointed to the Chair of Techno- 
logy, then recently founded in the University of Edinburgh, in con- 
nection with the Museum. It is needless to say in this meeting with 
what ability and success he discharged these duties. It was fondly 
hoped that in this congenial position, in the midst of friends and fellow- 
citizens who loved and appreciated him, and in the bosom of his own 
affectionate family, his constitution might gain strength, and that he 
might live to develop more fully, and perhaps in some new and original 
shape, the talents and genius of which he was possessed. But such 
was not the destiny appointed for him. He was sometimes, per- 
haps, too careless of consequences, where the call of supposed duty 
was heard, or where an opening of usefulness was afforded ; and in 
the middle of much ill health, and many warnings of danger, he 
continued to exert himself in a manner that would have been more 
appropriate in one of robuster frame. But his pleasure lay in the 
exercise of his intellectual faculties, in the advancement of science, 
and in availing himself of every opportunity to do good or show 
kindness ; and it is probable that the pious resignation with 
which he long contemplated liis precarious condition, and the state 
