systematic methods of astronomical work which Airy afterwards
developed to such a great extent at Greenwich, and which have been
subsequently adopted in many other places. No more profitable
instruction for the astronomical beginner can be found than that
which can be had by the study of these volumes, in which the Plumian
Professor has laid down with admirable clearness the true principles
on which meridian work should be conducted.

[PLATE: SIR GEORGE AIRY.
From a Photograph by Mr. E.P. Adams, Greenwich.]

Airy gradually added to the instruments with which the observatory
was originally equipped. A mural circle was mounted in 1832, and in
the same year a small equatorial was erected by Jones. This was made
use of by Airy in a well-known series of observations of Jupiter's
fourth satellite for the determination of the mass of the great
planet. His memoir on this subject fully ex pounds the method of
finding the weight of a planet from observations of the movements of
a satellite by which the planet is attended. This is, indeed, a
valuable investigation which no student of astronomy can afford to
neglect. The ardour with which Airy devoted himself to astronomical
studies may be gathered from a remarkable report on the progress of
astronomy during the present century, which he communicated to the
British Association at its second meeting in 1832. In the early
years of his life at Cambridge his most famous achievement was
connected with a research in theoretical astronomy for which
consummate mathematical power was required. We can only give a brief
account of the Subject, for to enter into any full detail with regard
to it would be quite out of the question.