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."

* * * * *

In July 1783 Herschel began his observations with his large twenty-foot
telescope, though it was in an unfinished state; and his sister watched
and waited with much apprehension when she knew him to be elevated some
fifteen feet or more on a temporary crossbeam instead of a safe gallery.
Here it is needful to explain, perhaps, that these huge astronomical
telescopes are not used like ordinary glasses, to one end of which the
observer applies his eye; the objects towards which the tube is directed
being thrown upon a large mirror, which is attached to it externally
at some distance from the ground. The observer, therefore, needs to
be mounted on an elevated platform or gallery, from which he can
conveniently inspect the mirror. One night, in a very high wind,
Herschel had scarcely descended from his station before the whole
apparatus came down; and his sister was in continual apprehension of
some serious accident. One such, indeed, occurred, and to herself. The
evening of the 31st of December had been cloudy, but as a few stars
shone forth about ten o'clock, hurried preparations were made for
observing. Herschel, standing at the front of the telescope, directed
his sister to make a certain alteration in the lateral motion, which was
done by machinery, on which the point of support of the tube and mirror
rested. At each end of the machine or trough was an iron hook, such as
butchers use for suspending their joints of meat; and having to run in
the dark across grou