0 stars, as compared with the corresponding lines in the
spectra of terrestrial elements (chiefly hydrogen), have been made,
but some of these appear to be affected by a constant error depending
on faulty adjustment of the Spectroscope.--Photographs of the Sun have
been taken with the Kew Photoheliograph on 186 days; and of these 377
have been selected for preservation. The Moon, Jupiter, Saturn, and
several stars (including the Pleiades and some double stars) have been
photographed with the Great Equatoreal, with fairly satisfactory
results, though further practice is required in this class of work.--I
would mention a supplemental mechanism which I have myself introduced
into some chronometers. I have long remarked that, in ordinary good
chronometers, the freedom from irregularities depending on mechanical
causes is most remarkable; but that, after all the efforts of the most
judicious makers, there is in nearly every case a perceptible defect
of thermal compensation. There is great difficulty in correcting the
residual fault, not only because an inconceivably small movement of
the weights on the balance-curve is required, but also because it
endangers the equilibrium of the balance. The mechanism adopted to
remedy the defect is described in a Paper in the Horological Journal
of July 1875 by Mr W. Ellis, and has received the approval of some
able chronometer-makers.--With respect to the Transit of Venus
Expeditions: The parties from Egypt and Rodriguez are returned. I am
in continual expectation of the arrival of the other parties. I
believe the eye-observations and the ordinary photographs to be quite
successful; I doubt the advantage of the Janssen; one of the
double-image-micrometers seems to have failed; and the
Zenith-telescope gives some trouble. At three stations at Rodriguez,
and three at Kerguelen, the observations appear to have been most
successful. At the Sandwich Islands, two of the stations appear to
have been perfectly successful (except that I fear that the Janssen
has failed), and a rich series of lunar observations for longitude is
obtained. At New Zealand, I grieve to say, the observations were
totally lost, entirely in consequence of bad weather. There has been
little annoyance from the dreaded 'black drop.' Greater inconvenience
and doubt have been caused by the unexpected luminous ring round
Venus.--With regard to the progress of my proposed New Lunar Theory:
Three computers are now steadily employ