specialists in grinding lenses, like Alvan Clark, of the U.S.A., and
others, have produced many large refractors.

Cooke, of York, made an object-glass, 25-inch diameter, for Newall, of
Gateshead, which has done splendid work at Cambridge. We have the
Washington 26-inch by Clark, the Vienna 27-inch by Grubb, the Nice
29-1/2-inch by Gautier, the Pulkowa 30-inch by Clark. Then there was
the sensation of Clark's 36-inch for the Lick Observatory in
California, and finally his _tour de force_, the Yerkes 40-inch
refractor, for Chicago.

At Greenwich there is the 28-inch photographic refractor, and the
Thompson equatoreal by Grubb, carrying both the 26-inch photographic
refractor and the 30-inch reflector. At the Cape of Good Hope we find
Mr. Frank McClean's 24-inch refractor, with an object-glass prism for
spectroscopic work.

It would be out of place to describe here the practical adjuncts of a
modern equatoreal--the adjustments for pointing it, the clock for
driving it, the position-micrometer and various eye-pieces, the
photographic and spectroscopic attachments, the revolving domes,
observing seats, and rising floors and different forms of mounting,
the siderostats and coelostats, and other convenient adjuncts, besides
the registering chronograph and numerous facilities for aiding
observation. On each of these a chapter might be written; but the
most important part of the whole outfit is the man behind the
telescope, and it is with him that a history is more especially
concerned.