The present Astronomer Royal, appreciating this possibility, has been searching by photography for Halley’s comet since November, 1907, although its perihelion passage will not take place until April, 1910.
FOOTNOTES:
[1] In 1874, when the writer was crossing the Pacific Ocean in H.M.S. “Scout,” Coggia’s comet unexpectedly appeared, and (while Colonel Tupman got its positions with the sextant) he tried to use the prism out of a portable direct-vision spectroscope, without success until it was put in front of the object-glass of a binocular, when, to his great joy, the three band images were clearly seen.
[2] Such as The World of Comets, by A. Guillemin; History of Comets, by G. R. Hind, London, 1859; Theatrum Cometicum, by S. de Lubienietz, 1667; Cometographie, by Pingré, Paris, 1783; Donati’s Comet, by Bond.
[3] The investigations by Von Asten (of St. Petersburg) seem to support, and later ones, especially those by Backlund (also of St. Petersburg), seem to discredit, the idea of a resisting medium.
15. THE FIXED STARS AND NEBULÆ.
Passing now from our solar system, which appears to be subject to the action of the same forces as those we experience on our globe, there remains an innumerable host of fixed stars, nebulas, and nebulous clusters of stars. To these the attention of astronomers has been more earnestly directed since telescopes have been so much enlarged. Photography also has enabled a vast amount of work to be covered in a comparatively short period, and the spectroscope has given them the means, not only of studying the chemistry of the heavens, but also of detecting any motion in the line of sight from less than a mile a second and upwards in any star, however distant, provided it be bright enough.
