quarta-feira, 4 de novembro de 2009

S. D. Humphrey

About one year since our attention was called to Lunar Daguerreotypes. Our first experiment was performed by taking a Daguerreotype of the Moon, which was done on the first of September, at half past ten, P.M., 1849. We prepared two plates as nearly alike as possible, and in the same manner as for taking a portrait; one of these was put in the Camera and exposed to the moon for two minutes and five seconds, then turning the regulating screw of the camera stand once around in order to allow space for another impression and exposing the plate one minute and one second; then regulating the camera as before. We obtained nine distinct impressions on the same plate, two as above, and seven as follows: the third exposure, fifteen seconds; the fourth, five; the fifth, four; sixth, three; the seventh, two; the eighth, one, and the ninth or last, instantaneous. Both plates were subject to the same operation, and like result produced: the impression given at the three second exposure was the most strongly marked and possessed a free development in light and shadow.
Any number of impressions may be had upon the same plate, as the sensitiveness is not in the least destroyed.
Our experiment was performed with a half-sized camera. It will readily be seen that the shorter time allowed the plate in the camera, the more distinct and strongly marked will be the impression. We find it necessary in experimenting for Lunar or Stellar Daguerreotypes that the plate should possess as great degree of sensitiveness as possible, by this means we obviate the evil which is occasioned by the motion of the Earth on its axis.
The result of our experiment in producing a Daguerreotype of the Moon, we forwarded to the President of Harvard University, and in answer, received the following kind and highly complimentary letter:-Harvard University, Cambridge, Oct. 31, 1849
Dear Sir,
-I have received your letter, accompanied by the Daguerreotype impressions of the Moon. I beg you will accept my thanks for this very curious and ingenious specimen of art.
The result is striking and remarkable.-We here perceive the apparent motion of the Moon, or rather the actual motion of the Earth on its axis, distinctly measure for half a minute's time, within the space of one-tenths of an inch. I have shown the impressions to several of our scientific gentlemen, who are much pleased with them, and applaud the skill with which they have been executed. Perhaps the art may at some future day be carried to such a degree of perfection, as to bring out the face of the moon sufficiently large for a map. This would be a most desirable attainment; since a map of the moon's surface can now be made only by the detached images presented to the eye through a telescope, and then transcribed by the hand. Such a map must necessarily be imperfect, and no two will precisely agree in all the parts. A Daguerreotype map would exhibit every feature with perfect exactness.
With best wishes for your success in this very ingenious art, I am, Sir, Jared Sparks.-S. D. Humphrey, Esq., Canandaigua.

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