Abstract
THE PARIS OBSERVATORY.—We have received Admiral Mouchez's Report for the year 1886, which was presented to the Council of the Observatory on February 4, 1887. Admiral Mouchez first refers to M. Lœwy's proposed new methods for determination of the constant of refraction and of the constant of aberration, the principles of which have already been explained in this column. With regard to refraction, it is pointed out that the exact determination of its amount at different altitudes and under varying conditions is of peculiar interest for an Observatory situated as that of Paris is, on the southern borders of a large city, so that the temperature of,the strata of air to the north and to the south will probably differ considerably. M. Mouchez hopes that during the current year it will be possible to attack these fundamental problems with an instrument constructed on M. Lœwy's plan. The great meridian instrument and the Gambey circle have been actively employed during the year, a grand total of 16,505 observations having been obtained, 798 of which refer to planets, including 148 of the sun and 128 of the moon. The principal meridian work continues, as in recent years, to be the re-observation of Lalande's stars. The equatorials have been employed in the observations of comets, minor planets, nebulæ, eclipses of Jupiter's satellites,: and occultations. It is almost unnecessary to remind our readers of the magnificent work in astronomical photography which has been carried on by the MM. Henry, and which embraces planets and their satellites, (Hyperion has Been photographed with an exposure of thirty-five minutes), the moon and, stars, including clusters and double-stars. M. Mouchez reports that he is considering how the stellar photographs may be most conveniently utilized for the formation of a catalogue, and states that, before final decision, he awaits the results of the then approaching meeting of the Astronomical Congress. The macro-micrometer devised by MM. Henry for measuring the relative positions of stars on the photographic plates is described in detail, and some results of double-star measurements made with this instrument are appended. It appears that these are of considerable accuracy, the mean error of a single measure for the double-star ζ Ursæ Majoris being o″.077 in distance and 0°.55 in position-angle.
Article PDF
Rights and permissions
About this article
Cite this article
Our Astronomical Column . Nature 36, 112–113 (1887). https://doi.org/10.1038/036112a0
Issue Date:
DOI: https://doi.org/10.1038/036112a0