The advantages to be gained by accurate photographs of the moon and
planets, that will permit great enlargements, are too obvious to call for
lengthened notice in such a rapid sketch as the present; for it is
principally in the observation of details that the eye cannot grasp with
the required delicacy, or with sufficient rapidity, that photography is so
essential for rapid and sure progress.

Like the sketches of a solar eclipse, the drawings that are made of
comets, and still more of nebulæ, even by the most accomplished 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