Abstract
THE NEW BRUCE SPECTROGRAPH FOR THE YERKES REFRACTOR.—This instrument has been provided from funds supplied in 1899 by Miss Catherine Bruce and the Rumford fund of the American Academy of Arts and Sciences. The arrangement of the various parts has been designed in view of obtaining the greatest possible rigidity and uniformity, of temperature, as the principal work for which it is to be employed is the determination of velocities in the line of sight. To this end several departures have been made from ordinary designs. The founction consists of two castings rigidly connected by a framework of steel tubes, one of these castings, weighing about 200 pounds, being attached to the massive terminal ring of the 40-inch refractor by eight bolts. The collimator tube is firmly attached to this and the second castings which latter also holds the framework on which the prism train is mounted. It was decided to use three prisms of such angle that the total deviation was 180°, thereby rendering the instrument more compact and free from flexure. The optical train. consisting of the correcting lens, collimating lens, prisms and camera lens, were made by Brashear from formulae supplied by Prof. Hastings. The correcting lens is 57 mm. aperture, and is so designed that when placed 100 cm. in front of the focus of the 40-inch for λ4500; the angular aperture of the large lens is hot altered. The performance of this lens has been found to be very satisfactory, rendering it possible to obtain a star spectrum, of uniform width from λ4300–λ4700.
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Our Astronomical Column . Nature 65, 374 (1902). https://doi.org/10.1038/065374a0
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DOI: https://doi.org/10.1038/065374a0