348 THE AMERICAN MONTHLY [Nov 



a microscope objective of an inch and a half focus to form 

 a second image, two inches and tliree-eightlis in diam- 

 eter, on the ground-glass of the camera. The clouds 

 made sharp focusing impossible. Only an imperfect 

 focus was obtained. The clock of the heliostat kept the 

 image steadily on the ground glass. 



During the eclipse sensitized pKates were substituted 

 for the ground-glass. Exposures were made when the 

 clouds were thin enough to permit. Thus six negatives 

 were secured. The first print shows the moon's black 

 disc, advancing apparently from the north-east across 

 the sun's disc, while the second shows the moon's disc, 

 passing off to the west. 



This is the first record of an attempt to use photomic- 

 rography aJs;tronomically. All of the necessary appa- 

 ratus could be easily packed in a trunk. If an unaided 

 telescope, objective were used to project an image of the 

 size obtained, a focus of twenty-one feet would be re- 

 quired; and the lens would have a diameter of about six- 

 teen inches. Such an objective properly mounted would 

 result in an instrument nearly half as large as the great 

 Lick telescope, with its photographic objective. By 

 using a portrait lens having a focus of fifteen or sixteen 

 inches, a size commonly used for ''cabinets" .in photog- 

 raphers' studios, instead of the portrait lens, the appa- 

 ratus will produce a negative image equal in size to that 

 produced by the unaided Lick lens; or, leaving the por- 

 trait lens in place, the same result could be obtained by 

 substituting for the microscope objective of one inch and 

 a hilf focus, another of about double the power, — one of 

 three-quarters of an inch focus. The Lick instrument 

 has a tube about fifty feet long and forty-two inches in 

 diameter, while this apparatus has two tubes less than 

 one foot long" and about one inch and six inches in 

 diameter respectively. To the smaller tube is attached 

 a camera with a bellows extending from oue to six 



