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The Total Eclipse at the Observatory.

The work done during the total eclipse of the moon on last Saturday evening at the astronomical observatory was in every way successful. The observations were carried on under the direct personal supervision of Professor Pickering who co-operated with the authorities at the Russian observatory of Pulkova in ascertaining the precise time when certain faint stars were occulted by the moon. These stars, usually invisible when in the neighborhood of the moon, on account of the brilliancy of its light, became visible by reason of the shadow of the earth falling on the moon, the light of which was thereby diminished. So that by determining the time of the occultation of these stars, whose positions are exactly known, the moon's position was ascertained more accurately than it has been heretofore. In addition to this work in co-operation with the Russian observers, a special effort was made to obtain photographs of the moon in the various stages of the eclipse. Photographs of the moon's spectrum were also taken, and these contribute in an indirect way to the study of light, the immediate result being a determination of colors.

The fifteen-inch equatorial telescope was in charge of Mr. O. C. Wendell, while Mr. W. H. Pickering directed the general photographic work. Professor Pickering had twelve persons assisting in one way or another during the three or four busy hours. The photographic plates obtained were not all developed at once, but a sufficiency of each set to show that the apparatus was in good order. The time signal of the observatory was critically compared on Saturday, and was found to be correct, within one-tenth of a second.

The observations were entirely satisfactory, and although the cyclonic conditions had a tendency to produce a tremulousness in the upper atmosphere, disadvantageous to visual observations, this did not diminish the opportunities for photography.

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