This historic book may have numerous typos and missing text.
Purchasers can download a free scanned copy of the original book
(without typos) from the publisher. Not indexed. Not illustrated.
1862 Excerpt: ...as the Fellows of this Society well know, was one
of extreme complexity; for not only must the motion of the
clock-work be perfectly smooth and equable, but it must also be
capable of acceleration and retardation, to keep pace, so to speak,
with the ever-varying velocity of the Moon in the heavens--a
variation compounded of its diurnal motion and its ever-changing
velocity in its orbit. Lastly, by a rare and happy combination of
chemical with mechanical skill, the time necessary for the exposure
of the collodion film was materially shortened. The final result is
this, --that images of the Moon have been repeatedly taken in the
focus of the mirror, admitting of very considerable amplification,
and exhibiting details on the Moon's surface sufficiently clear to
admit of delineation under a microscope provided with a camera
lucida, and thereby furnishing materials for a more accurate
selenography than has heretofore existed. Neither must we
altogether omit that by stereoscopically combining images of the
Moon taken in different phases of her librations, more particularly
enlarged copies eight inches in diameter, Mr. De La Rue has brought
to light details of dykes, and terraces, and furrows, and
undulations on the lunar surface, of which no certain knowledge had
previously existed, and which I have had the exquisite pleasure of
beholding in his Observatory at Cranford. "Man looks aloft, and,
with erected eyes, Beholds his own hereditary skies." I must now
turn to a department in Celestial Photography, where Mr. De La Rue
stands almost alone. I speak of Heliography: In April 1854, Sir
John Herschel, in a letter to Colonel Sabine, recommended that
daily photographic records of the Sun should be obtained at some
observatory. Accordingly, the Royal Society ...
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