ewall to the University of Cambridge, a few weeks
before his death, April 21, 1889. Under the care of his son, Mr. Frank
Newall, it has proved highly efficient in the delicate work of measuring
stellar radial motions.

Close upon its construction followed that of the Washington 26-inch, for
which twenty thousand dollars were paid to Alvan Clark. The most
illustrious point in its career, entered upon in 1873, has been the
discovery of the satellites of Mars. Once known to be there, these were,
indeed, found to be perceptible with very moderate optical means (Mr.
Wentworth Erck saw Deimos with a 7-inch Clark); but the first detection
of such minute objects is a feat of a very different order from their
subsequent observation. Dr. See's perception with this instrument, in
1899, of Neptune's cloud-belts, and his refined series of micrometrical
measures of the various planets, attest the unimpaired excellence of its
optical qualities.

It held the primacy for more than eight years. Then, in December, 1880,
the place of honour had to be yielded to a 27-inch achromatic, built by
Howard Grubb (son and successor of Thomas Grubb) for the Vienna
Observatory. This, in its turn, was surpassed by two of respectively
29-1/2 and 30 inches, sent by Gautier of Paris to Nice, and by Alvan
Clark to Pulkowa; and an object-glass, three feet in diameter, was in
1886 successfully turned out by the latter firm for the Lick Observatory
in California. The difficulties, however, encountered in procuring discs
of glass of the size and purity required for this last venture seemed to
indicate that a term to progress in this direction was not far off. The
flint was, indeed, cast with comparative ease in the workshops of M.
Feil at Paris. The flawless mass weighed 170 kilogrammes, was over 38
inches across, and cost 10,000 dollars. But with the crown part of the
designed achromatic combination things went less smoothly. The
production of a perfect disc was only achieved after _nineteen_
failures, involving a delay of more than two years; and the glass for a
third lens, designed to render the telescope available at pleasure for
photographic purposes, proved to be strained, and consequently went to
pieces in the process of grinding. It has been replaced by one of 33
inches, with which a series of admirable lunar and other photographs
have been taken.

Nor is the difficulty in obtaining suitable material the only obstacle
to increasing the size of refr