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Updated: May 26, 2025
The next in importance was a nine and a half-inch instrument at Dorpat, in Russia. This was the telescope through which the astronomer Struve made his earlier studies and discoveries. His field of observation was for the most part the fixed and double stars. At this time the largest instrument in the United States was the five-inch refractor of Yale College.
Now, the reader may ask, "Since reflectors require no correction for color dispersion, while that correction is only approximately effected by the combination of two kinds of lenses and two kinds of glass in a refractor, why is not the reflector preferable to the refractor?" The answer is, that the refractor gives more light and better definition.
It seemed as if every electric light in the house found some kind of a refractor in the thousands of gems of which it was composed, and many of the brilliant light effects of the stage were dimmed in their lustre by the persistent intrusion of Mrs. Burlingame's glory upon my line of vision.
And it is noteworthy in this connection that Professor Barnard obtained in 1894, with the great Lick refractor, "suggestive and impressive views" disclosing details of light and shade on the gray-green patches so intricate and minute as almost to preclude the supposition of their aqueous nature. The closeness of the terrestrial analogy has thus of late been much impaired.
An improved instrument was erected in the autumn of the same year, and the fifty-one stars, bright enough for determination with a refractor of 11 inches aperture, were promptly taken in hand. A list of their motions in the line of sight, published in 1892, was of high value, both in itself and for what it promised.
Yet not one of all the undergraduates felt she could have made a wiser choice. She swept among them. Her own intrinsic radiance was not all that flashed from her. She was a moving reflector and refractor of all the rays of all the eyes that mankind had turned on her. Her mien told the story of her days. Bright eyes, light feet she trod erect from a vista whose glare was dazzling to all beholders.
The purpose of a telescope of either description is, first, to form an image of the object looked at by concentrating at a focus the rays of light proceeding from that object. The refractor achieves this by means of a carefully shaped lens, called the object glass, or objective. The reflector, on the other hand, forms the image at the focus of a concave mirror.
Mills's visit was that in December, 1874, I was invited to visit the European workshops as an agent of the Lick trustees, with a view of determining whether there was any chance of getting the telescope made abroad. The most difficult and delicate question arose in the beginning; shall the telescope be a reflector or a refractor?
The satisfactory nature of its performance is vouched for by the observations made with it upon Jupiter's new satellite in December, 1892. This instrument, to which a Newtonian form has been given, had no rival in respect of light-concentration at the time when it was built. It has now two the Paris 50-inch refractor and the Yerkes 5-foot reflector.
As they went on, the purple light continued to flash more and more rapidly, but still nothing was to be seen. "Take number six visiplate, will you, Mart? It's telescopic, equivalent to a twenty-inch refractor. I'll tell you where to look in a minute this reflector increases the power of the regular indicator." He studied meters and adjusted dials.
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