20 
REPORT OF THE 
Accustomed to the use of the gas-furnace, Mr. Harcourt 
turned it to experiments on transparent compounds of fusion, 
which might he made to have refractive indices beyond the 
ordinary ranges, combined with scales of dispersion more 
favorable to achromaticity. In this he was guided by the trials 
of Faraday to prepare glass for optical purposes. Many years 
since, the writer, who was often helpful in this way, ground one 
of the earliest of the Flarcourt glasses into a lens, and found it 
indeed a highly refractive clear substance, but too much tra¬ 
versed by strise to be of practical use. 
When some years since Mr. Harcourt removed his residence 
to the family seat at Nuneham, near Oxford, he constructed 
furnaces of a different kind for the carrying on of these expe¬ 
riments, and followed them with the zeal, resolution and 
patience which had always characterized his firm and well- 
regulated mind. At an age when most men cease from con¬ 
tinuous literary and scientific work, he, with failing sight but 
perfect memory, was indefatigable in training an assistant and 
superintending his work ; making many new combinations with 
substances untried before, and now selected for quality of 
fusion, resistance to atmospheric vicissitudes, range of refraction 
and specific action on different rays of the spectrum. Thus it 
was hoped finally to acquire glasses of definite and mutually 
compensative dispersions, so as to make perfectly achromatic 
combinations. After innumerable trials, and the production of 
glass of extremely various quality, Mr. Harcourt,* continuing 
his inspection to the last, had the satisfaction of belieHng that, 
though he could not remain to witness it, a good result had 
been assured, and that Professor Stokes, to whom all the speci¬ 
mens were submitted for scrutiny, would be able to construct a 
lens of sufficient size to be fairly tried, and thus crown the long- 
continued labour with a permanent benefit to science. 
It was hoped that a full account of these experiments might 
have been prepared by the author of them, for his strong mind 
felt little of the weight of eighty years, and overruled the 
bodily infirmities of age. But it was a character of the man 
never to cease experimental or literary research till he was 
satisfied; resolute to contend with difficulties till all were over- 
