Photographs of Nebulæ and Clusters, Made with the Crossley Reflector

A director’s observing program used the Crossley reflector to photograph brighter nebulæ and star clusters, producing negatives for most of a planned set and reproducing sixty-eight larger subjects as plates. The images revealed many previously unrecorded nebulæ and indicated that spiral structure is common; a catalogue of new objects with accurately measured positions is included. The volume also describes the telescope and observing methods, discusses the technical challenges of photographic reproduction and plate making, and provides lists of subjects, positions, illustrations, and explanatory notes to support technical study and further astronomical work.