9d Memoir of the late Mr William Blackie. 



labours, almost exclusively, to practical optics, '.n hopes of 

 being able to obtain a livelihood by disposing of lenses and 

 other apparatus, in the construction of which he now began 

 to evince considerable dexterity. 



He persevered in this for about twelve months, when, find- 

 ing that his success did not equal his expectations, he once 

 more returned to his former employment. For a short time 

 he laboured in the Experimental Garden at Inverleith, but 

 left it abruptly, in consequence of what he considered bad 

 usage. 



He now thought of becoming an engineer ; and, with this 

 view, endeavoured to procure employment in some engine 

 factory, but in vain. This fresh disappointment brought him 

 back to his lenses with new zest ; and he spent the four re- 

 maining years of his life almost entirely in the manufacture 

 of these, and that with a degree of success^ as to the excel- 

 lence of their performance, that has rarely, if ever, been 

 equalled. The fact of Blackie's attaining such eminence as 

 an artificer in work so delicate and minute as that of the con- 

 struction of microscope-lenses of high power, notwithstand- 

 ing his having been fully exercised for many years in the 

 use of so large a tool as the spade, may be regarded as a very 

 interesting addition to the history of the human hand ; and 

 as supplying another striking proof of the wonderful plasticity 

 with which it has been endowed by the all-wise Author of 

 our being. 



It was about this time (the beginning of 1834), that he suc- 

 ceeded in forming a diamond lens having a focus of 3 -90th 

 of an inch, and a radius of l-35th of an inch, which magnified 

 549 times. This, it is believed, was the first lens of the kind 

 ever made in Scotland. His successful effort was the means 

 of bringing him and his works under the notice of Sir David 

 Brewster, Professor Forbes, and other philosophers, who sub- 

 sequently employed him in various pieces of work connected 

 with practical optics, and continued sedulously to interest 

 themselves in his welfare to the close of his life. Encouraged 

 by such patronage, he continued his work steadily, but still 

 in the most quiet and simple manner possible. He usually 

 wrought at a common table in his grandfather's kitchen : all 



