Our Astronomical Column

Abstract

THE HELIOMETER OF THE YALE COLLEGE OBSERVATORY.—From Dr. Elkin's report of the work done during the year ending June I, 1885, we learn that the principal object of research has been the triangulation of the Pleiades, to which work the heliometer was devoted from September 188410 March 1885. It was originally intended to confine the investigation to the stars measured at Konigsberg and to carry out only one method of triangulation. The scheme has been extended, however, to include all the stars in the Bonn Durchmusterung, within certain limits, down to magnitude 9.2, making sixty-nine stars in all, and also to obtain a determination of the relative positions of the stars which should be strictly comparable with the Königsberg work, viz. measurement of distances and angles of position of the stars from Alcyone. The observations have all been reduced provisionally; the final reduction cannot be undertaken until the results of the meridian observations of the end stars of two zones serving to determine the scale value and zero of position have been received from the observatories which have consented to make them. Measures of the moon from neighbouring stars have also been made on thirty-six nights near the first and last quarters, and the diameter of the moon has been measured at opposition on seven occasions. Observations have also been made of the diameter of Venus, the outer ring of Saturn, and of Titan referred to its primary. It is now proposed to devote the heliometer to systematic investigations in stellar parallax, and, judging from the results which have been obtained by Gill and Elkin at the Cape, we may expect that most valuable work will be done in this direction with the heliometer at Yale College also.