Photographs of Nebulæ and Clusters, Made with the Crossley Reflector

by James Edward Keeler

[6] Mem. R. A. S., 46, 173.

[7] Mon. Not. R. A. S., 48, 280, 1888.

[8] Mon. Not. R. A. S., 49, 297. The construction here described is not followed exactly in the Crossley apparatus. The guiding eyepiece slides freely when not held by a clamp. Pin-holes for preventing fogging are unnecessary when red light is used.

[9] It so happens that the tension of the vertical thread is such that it begins to slacken when the temperature falls to within about 2° of the dew point. The thread thus forms an excellent hygrometer, which is constantly under the eye of the observer. When the thread becomes slack, it is time to cover the mirrors.

[10] Mon. Not. R. A. S., 48, 352.

[11] The following list includes all papers of interest:

“Photographic Observations of Comet I, 1898 (Brooks), made with the Crossley Reflector of the Lick Observatory.” A. J. No. 451, 19, 151; see also Ap. J., 8, 287.

“The Small Bright Nebula near Merope,” Pub. A. S. P., 10, 245.

“On Some Photographs of the Great Nebula in Orion, taken by means of the Less Refrangible Rays in its Spectrum,” Ap. J., 9, 133. See also Pub. A. S. P., 11, 70; Ap. J., 10, 167; A. N., 3601.

“Small Nebulæ discovered with the Crossley Reflector of the Lick Observatory,” Mon. Not. R. A. S., 59, 537.