Reading Nature, Observing Science: Examining Material Practices in the Lick Observatory Archives and Kenneth S. Norris Papers

The Trouvelot Astronomical Drawings Manual, 1882.

In the book, Trouvelot writes, "Those unacquainted with the use of optical instruments generally suppose that all astronomical drawings are obtained by the photographic process,  and are, therefore, comparatively easy to procure; but this is not true.  Although photography renders valuable assistance to the astronomer in the case of the Sun and Moon, as proved by the fine photographs of these objects taken by M. Janssen and Mr. Rutherfurd; yet, for other subjects, its products are in general so blurred and indistinct that no details of any great value can be secured. A well-trained eye alone is capable of seizing the delicate details of structure and of configuration of the heavenly bodies, which are liable to be affected, and even rendered invisible, by the slightest changes in our atmosphere."

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