PHOTOGRAPHIC ACCESSORIES OF THE DRAKE OBSERVATORY. 
BY D. W. MOREHOUSE. 
The application of photography to astronomical research is one of the 
great achievements of science. While the “pioneering experiments” date 
back to the days of Dr. J. W. Draper and Warren de la Rue, the vastly 
interesting and valuable results belong to the present decade. 
Astro-physics, “the new-born child of Astronomy”, owes its phenomenal 
growth and development, if not its birth, to the photographic lens and 
camera. 
It is certain that the sensitive plate will never be as satisfactory for 
general observations as the eye but it is vastly superior for some kinds 
of observations. Take the nebulae for example. Here the camera will 
obtain in the course of a few hours information and detail hopelessly 
beyond the power of any human eye. Moreover, it has no nerves or pre- 
conceived ideas; and you can depend upon its impressions. 
The eight-and-one-fourth-inch equatorial of the Drake Observatory 
is equipped with a third or photographic lens. It was ground by Dr. J. A. 
Brashear, which fact alone is sufficient guarantee as to its quality. At 
the time the instrument was purchased, there was no provision made for 
a guiding telescope; and, as the exposures require hours in some instances, 
a guiding appartus is an absolute necessity. To obviate this deficiency, 
the small telescope or finder which is always attached to the side of a 
large telescope was pressed into service. One could hardly expect this to 
succeed, for it is ill adapted to the work in every respect. However, some 
fairly good results were obtained in this way; just enough to stimulate 
a great desire to do better. Feeling that it was not possible to do much 
better with the finder and that a new guiding telescope was entirely out 
of reach, I cast about for some solution of my problem; and I feel that I 
have happily found it in the simple and inexpensive right-angled eye- 
piece which I had attached to the side of my camera. 
The heavy brass ring shown in Fig. 1 is rigidly attached to the eye end 
of the telescope by four heavy bolts and carries on its outer end the 
heavy camera box. The right-angled prism clearly shown in the cut 
overhangs the edge of the photographic plate and reflects the image of 
the guide star into the magnifying eye-piece attached to the side of the 
box. Here the image is made to coincide, by means of slow motion 
screw's, wnth the intersection of two fine spider-lines. These lines are 
illuminated by a small incandescent lamp contained in the eye-piece tube. 
Fig. 2 show's the camera in place and ready for an exposure. 
By this simple device, I have a guiding telescope of the same aperture 
and focal length as my photographic, and just as rigid. Fig. 3 shows the 
observer at work. Of course, the strain on eve and nerve is so great that 
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