The subject ‘nebulae and star clusters’, centred on the nineteenth century, has hitherto not historically been treated in detail. At best, a few aspects were studied and occasionally results were published. Particularly the ‘history of the NGC’ is new territory and the present work is the first of its kind. The following comprehensive summary concentrates on the following issues (see also Chapter 1):

1. (1) the subject and line of questioning

2. (2) the importance of the New General Catalogue and the motivation of the work

3. (3) objects, observers and methods

4. (4) milestones of the cataloguing of nebulae and star clusters (non-stellar objects)

5. (5) statistical analysis and the way ahead

THE SUBJECT AND LINE OF QUESTIONING

This work deals with the discovery, visual observation, description and cataloguing of nebulae and star clusters, focusing on the nineteenth century. Astronomers, sites and a large number of objects are presented. The climax of the development, starting with William and John Herschel was the publication of the New General Catalogue (NGC) by John Louis Emil Dreyer in 1888. The date also marks the transition from classical astronomy based on visual observations and positional measurements to modern astrophysics represented by spectroscopy, photography and photometry.