In addition to all this
labour, he perfected a twelve-inch speculum of vast magnifying power
before the spring of 1784; and many hours were spent at the
turning-bench, as not a night clear enough for observing ever passed
without the devising of improvements in the mounting and motion of
the various instruments then in use, or the test and trial of
newly-constructed "eyepieces," most of which were executed by Herschel's
own hands. "Wishing to save his time, he began to have some work of that
kind done by a watchmaker, who had retired from business, and lived on
Datchet Common; but the work was so bad, and the charges [were] so
unreasonable, that he could not be employed. It was not till some time
afterwards, in his frequent visits to the meetings of the Royal Society
(made in moonlight nights), that he had an opportunity of looking about
for mathematical workmen, opticians, and founders. But the work seldom
answered expectation, and it was kept to be executed with improvements
by Alexander during the few months he spent with us.
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