hed artists,
are all, to say the least, open to doubt in their delicate details. And
the truth of this is so obvious, that it is the expressed opinion of an
able astronomer that a single photograph of the nebula of Orion, taken by
Mr. Common, would be of more value to posterity than the collective
drawings of this interesting object so carefully made by Rosse, Bond,
Secchi, and so many others.

Another most important branch of astronomy, that is receiving very great
attention at present, is the mapping of the starry heavens; and herein
photography will perhaps do its best work for the astronomer. The trial
star map by the brothers Henry, of a portion of the Milky Way, which they
felt unable to observe satisfactorily by the ordinary methods, is so near
absolute perfection that it alone proves the immense superiority of the
photographic method in the formation of star maps. Fortunately this
subject, which is as vast as it is fundamental, is being taken up
vigorously. The Henries are producing a special lens for the work; Mr.
Grubb is constructing a special Cassgrain reflector for Mr. Roberts of
Maghull; and the Admiralty have instructed Mr. Woods to make this part of
his work at the Cape Observatory, under the able direction of Dr. Gill.
Besides star maps, clusters, too, and special portions of the heavens are
being photographed by the Rev. T.E. Espin, of West Kirby; and such
pictures will be of the greatest value, not only in fixing the position at
a given date, but also aiding in the determination of magnitude, color,
variability, proper motion, and even of the orbits of double and multiple
stars, and the possible discovery of new planets and telescopic comets.

Such are some of the many branches of astronomy that are receiving the
most valuable aid at present from photography; but the very value of the
gift that is bestowed should make exaggeration an impossibility.
Photography can well afford to be generous, but it must first be just, in
its estimate of the work that has still to be done in astronomy
independently of its aid; and although the older science points with just
pride to what is being done for her by her younger sister, still she must
not forget that now, as in the future, she must depend largely for her
progress, not only on the skill of the photographer and the mathematician,
but also on the trained eye and ear and hand of her own indefatigable
observers.--_S.J. Perry, S.J., F.R.S., in Br. Jour. of Photog