426 SKC. 1 1 .-^ASTRONOMY. 



1869. Specimens of Photographic Multiplication and 

 Reversion of astronomical drawings of nebula and comets (Dr. 

 Vogel's method). 



Dr. H. C. Vogel and Dr. Osiv. Lohse, Potsdam. 



1870. Lunar and Solar Photographs. 



Warren De La Rue, D.C.L., F.R.S, 



The lunar photographs consist of: 



1st. A series of original lunar negatives obtained in the focus of an equa- 

 torial reflector of 10 feet focal length and 13 inches aperture. These should 

 be examined with a lens in order to render the details visible. It will be 

 noticed that the diameter of the lunar images varies in the several negatives, 

 this arises from the moon being sometimes nearer to and sometimes more 

 distant from the earth according to her position in her orbit. 



2nd. A series of first enlargements 9-inches in diameter, collodion on glass 

 transparent positives. 



3rd. A series of paper positives 1 8 inches in diameter printed from nega- 

 tives obtained by enlargement from the 9-inch positives. 



4th. One paper positive 38 inches in diameter. The solar photograph is 

 an original negative on a scale of 3 feet to the sun's diameter, obtained with 

 the same reflector with the addition of a secondary magnifier placed at the 

 eye end of the telescope. 



1870a. Enlarged Solar Photographs, by Mr. Rutlicrfurd 

 of New York. J. Norman Lockyer, F^R.S. 



VIII. CHRONOGRAPHS. 



1871. Wheatstone's Magnetic Chronograph, for mea- 

 suring very small intervals of time. 



The Council of King's College, London. 



1872. Groves's Chronograph, for astronomical calculations, 



for railway speed, and speed of machinery. W. Groves. 



1873. Yvon Villarceau's Astronomical Chronograph. 



Breguct, Paris. 



1874;. Carrington's Astronomical Chronograph, made 

 by Smith and Beck. Dr. Stone. 



1875. Electro-magnetic Registering Apparatus. 



M. Th. Edelmann, Physico- Mechanical Institute, Munich. 

 Ji':3v."' ^8 adi lo gc*7flTQ .8331 







