method of simplification devised at
Koenigsberg. Anticipated as an inventor, he could still be of eminent use
as a promoter of these valuable improvements; and, carrying them out on
a large scale in the star-catalogue of the Astronomical Society
(published in 1827), "he put" (in the words of Herschel) "the
astronomical world in possession of a power which may be said, without
exaggeration, to have changed the face of sidereal astronomy."[151]

His reputation was still further enhanced by his renewal, with vastly
improved apparatus, of the method, first used by Henry Cavendish in
1797-98, for determining the density of the earth. From a series of no
less than 2,153 delicate and difficult experiments, conducted at
Tavistock Place during the years 1838-42, he concluded our planet to
weigh 5.66 as much as a globe of water of the same bulk; and this result
slightly corrected is still accepted as a very close approximation of
the truth.

What we have thus glanced at is but a fragment of the truly surprising
mass of work accomplished by Baily in the course of a variously occupied
life. A rare combination of qualities fitted him for his task. Unvarying
health, undisturbed equanimity, methodical habits, the power of directed
and sustained thought, combined to form in him an intellectual toiler of
the surest, though not perhaps of the highest quality. He was in harness
almost to the end. He was destined scarcely to know the miseries of
enforced idleness or of consciously failing powers. In 1842 he completed
the laborious reduction of Lalande's great catalogue, undertaken at the
request of the British Association, and was still engaged in seeing it
through the press when he was attacked with what proved his last, as it
was probably his first serious illness. He, however, recovered
sufficiently to attend the Oxford Commemoration of July 2, 1844, where
an honorary degree of D.C.L. was conferred upon him in company with Airy
and Struve; but sank rapidly after the effort, and died on the 30th of
August following, at the age of seventy, lamented and esteemed by all
who knew him.

It is now time to consider his share in the promotion of solar research.
Eclipses of the sun, both ancient and modern, were a speciality with
him, and he was fortunate in those which came under his observation.
Such phenomena are of three kinds--partial, annular, and total. In a
partial eclipse, the moon, instead of passing directly between us and
the sun,