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Solar eclipse of August 7, 1869
356
Mec]~anics, Physics, and C/~cmistry. SOLAR ECLIPSEOF AUGUST 7, 1869, ]~EPORT OF ~[R. O. H .
~VILLtRD.
_Prof. Henry Morton, Ph.D. Sir,--Having been requested by you to take charge of the photographic preparation and work for the High School telescope, placed in charge of Prof. A. M. Mayer, at Burlington, Iowa, I made the following arrangements: The plates and plate-holders being 4½ inches square, I first adjusted the camera so as to secure an image of the sun 2"4 inches in diameter, and then, by repeated trial, found the best actinic focus; adjustment being-made by moving the entire eye-piece and camera toward and from the objective, by means of the regular rack and pinion belonging to the telescope. Bringing the eye-piece nearer to the objective shortened the tbcus of the combination, and was thus equivalent to a withdrawal of th~ sensitive plate. The distance between the best visual and actinic foci was about ~% of au inch. I had the requisite chemicals preparcd according to the following formulm. BATH. Fused Nitrate of Silver..: .............................. 45 g r s . Distilled water ................................................ 1 oz. N i t r i c A c i d . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 d r o p s to t h e g a l l o n .
Iodized by immersing an 8 by 10 plate flowed with the following collodion: COLLODION. :Ether ............................................................. 1 oz. Alcohol ........................................................ 1 oz. C o t t o n ( P y r o x y l i n e ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 g r s . I o d i d e o f A m m o n i u m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . :. 10 g r s . Bromide of Potassium .................................... 4 grs, DEVELOPER. Protosulphate of Iron .................................... 6 grs. Water ......................................................... ½ gall. Acetic Acid No. 8 .......................................... 4 oz. FIXING
SOLUTION.
H y p o s u l p h i t e o f S o d a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 oz. Water ................................................... :..1 q u a r t .
The exposures during the partial phases were made by the arrangement described in your report, and the smallest slide (~'.e. that having an opening of ~ of an inch) was used until the last two pictures, which were exposed with ! inch opening. Only one spring was used throughout. Six exposures were made during totality, the first two of 5 seconds each, the last four of 8 seconds each. The plates were prepared by Mr. Phillips and developed by Mr. Mahoney with the assistance of Mr. Leisenring, of Galesburgh.
Mec]~anics, Physics, and C/~cmistry. SOLAR ECLIPSEOF AUGUST 7, 1869, ]~EPORT OF ~[R. O. H .
~VILLtRD.
_Prof. Henry Morton, Ph.D. Sir,--Having been requested by you to take charge of the photographic preparation and work for the High School telescope, placed in charge of Prof. A. M. Mayer, at Burlington, Iowa, I made the following arrangements: The plates and plate-holders being 4½ inches square, I first adjusted the camera so as to secure an image of the sun 2"4 inches in diameter, and then, by repeated trial, found the best actinic focus; adjustment being-made by moving the entire eye-piece and camera toward and from the objective, by means of the regular rack and pinion belonging to the telescope. Bringing the eye-piece nearer to the objective shortened the tbcus of the combination, and was thus equivalent to a withdrawal of th~ sensitive plate. The distance between the best visual and actinic foci was about ~% of au inch. I had the requisite chemicals preparcd according to the following formulm. BATH. Fused Nitrate of Silver..: .............................. 45 g r s . Distilled water ................................................ 1 oz. N i t r i c A c i d . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 d r o p s to t h e g a l l o n .
Iodized by immersing an 8 by 10 plate flowed with the following collodion: COLLODION. :Ether ............................................................. 1 oz. Alcohol ........................................................ 1 oz. C o t t o n ( P y r o x y l i n e ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 g r s . I o d i d e o f A m m o n i u m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . :. 10 g r s . Bromide of Potassium .................................... 4 grs, DEVELOPER. Protosulphate of Iron .................................... 6 grs. Water ......................................................... ½ gall. Acetic Acid No. 8 .......................................... 4 oz. FIXING
SOLUTION.
H y p o s u l p h i t e o f S o d a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 oz. Water ................................................... :..1 q u a r t .
The exposures during the partial phases were made by the arrangement described in your report, and the smallest slide (~'.e. that having an opening of ~ of an inch) was used until the last two pictures, which were exposed with ! inch opening. Only one spring was used throughout. Six exposures were made during totality, the first two of 5 seconds each, the last four of 8 seconds each. The plates were prepared by Mr. Phillips and developed by Mr. Mahoney with the assistance of Mr. Leisenring, of Galesburgh.