National Geographic : 1900 Aug
THE SCIENTIFIC WORK OF THE NATIONAL GEOGRAPHIC SOCIETY'S ECLIPSE EXPEDITION TO NORFOLK, VA. By SIMON NEWCOMB, LL. D. The expeditions spread along the path of total eclipse in the acces sible regions over which it swept were so numerous and so well equipped that it was quite unnecessary for the National Geographic Society to attempt their work, even had it possessed the means of doing so. Its plan was therefore restricted to a modest attempt to supplement the work of others by such observations as did not require elaborate instrumental means or long previous preparation. The operations finally undertaken were three in number: 1. Observations of the times of contact and their comparison with prediction. 2. Photographing the sky during totality, the corona and other surroundings of the sun included, with the view of finding any un known object and of making photometric comparison of the light of the sky on the disk of the moon with that away from the sun. 3. Observations of the so-called shadow bands. The following imperfect summary of results is all that it is possible to prepare at the present time. TIMES OF CONTACTS As the observer had no optical instrument but a good spyglass, the second and third contacts were the only ones seriously attempted. Such an instrument, is as good as a larger one for these contacts. The time was determined by a pocket watch, which was compared with the standard clock at the Naval Observatory the day before and the day after the eclipse. The corrections of the watch to eastern standard time thus determined were: May 27................. ................ Corr. =-- 2SS .2 May 29 ................... .............. Corr.= - 28.5 The correction at the time of the eclipse would then be - 28 s 3. It may be remarked'that by a long series of comparisons the accidental daily variation of the watch is about ± 0.2, and that the mean rate during the three weeks before the eclipse chanced to be about zero.