that purpose. . . . I had also to ascertain their places
by a transit instrument lent for that purpose by Mr. DALRYMPLE; but,
after many fruitless attempts, it was seen that the instrument was,
perhaps, as much in fault as my observations."

In 1783 HERSCHEL says:

"I have now finished my third review of the heavens. The first was
made with a Newtonian telescope something less than seven feet focal
length, a power of 222, and an aperture of four and a half inches.
It extended only to stars of the first, second, third, and fourth
magnitudes. My second review was made with an instrument much
superior to the other, of 85.2 inches focus, 6.2 inches aperture,
and power 227. It extended to all the stars of HARRIS'S maps and
the telescopic ones near them, as far as the eighth magnitude. The
Catalogue of Double Stars and the discovery of the _Georgium Sidus_,
were the results of that review. The third was with the same
instrument and aperture, but with a power of 460. This review
extended to all the stars of FLAMSTEED'S Catalogue, together with
every small star about them, to the amount of a great many thousands
of stars. I have, many a night, in the course of eleven or twelve
hours of observation, carefully and singly examined not less than
400 celestial objects, besides taking measures, and sometimes
viewing a particular star for half an hour together."

The fourth review began with the twenty-foot, in 1784.

"My brother began his series of sweeps when the instrument was yet
in a very unfinished state, and my feelings were not very
comfortable when every moment I was alarmed by a crack or fall,
knowing him to be elevated fifteen feet or more on a temporary
cross-beam, instead of a safe gallery. The ladders had not even
their braces at the bottom; and one night, in a very high wind, he
had hardly touched the ground before the whole apparatus came down.
Some laboring men were called up to help in extricating the mirror,
which was, fortunately, uninjured, but much work was cut out for
carpenters next day. I could give a pretty long list of accidents
which were near proving fatal to my brother as well as myself. To
make observations with such large machinery, where all around is in
darkness, is not unattended with danger, especially when personal
safety is the last thing with which the mind i