The privileging of the public and published has tended to overshadow fundamental factors in the study of scientific visualization, such as the nature of and the significant role played by visual inscriptions and processes within a scientist’s journals, notebooks, observing books, laboratory books, or just ordered sheets of unbound paper. Such internal, tentative, and preliminary sketches or drawings, or what I label «working images» (a variety of sketches or drawings including diagrams, outlines, schematics, «skeletons», mimetic representations, and so on, to be found within the internal records of an observational program) have to some extent or other, to be sure, been used as sources for historians, sociologists, and philosophers of science. But for the most part this has been true only in so far as they have been employed to shed light on final published images or text, and the printing and editorial processes involved. I am, however, more interested on what light a study of the working images and their various functions can shed on the nature of the practices and processes involved in scientific observation.

The general driving force behind this book, therefore, will be the question: what can the drawings of the nebulae and star clusters tell us about the nature of scientific observation in the 19th century? This question has been typically answered, to be sure, by way of photography and self-writing instruments, stereoscopes and kaleidoscopes; but rarely, if ever, by way of the hand, its implements (paper and pencil), and the pragmatic processes into which these were embedded. In the very least, we must ascertain and get the multifarious practices of the latter right (which are neither homogenous nor obvious) before we can go on to discover what precisely was supplanted by the incursion of the former; and it is this that I attempt to do in the following work. [2]

Furthermore, one of the important features overshadowed by the privileging of the published has been the multiple ways in which all sorts of working images move through a series of observing books or sheets of paper. A working image does not stand alone, nor does it stand still. But nor do working images have some kind of intrinsic agency of their own. Rather, they are processed and managed, copied and traced, added to and supplemented, compared and contrasted, selected and multiplied. This is made possible for the working images by internally established and selected processes in which they are made to perform and operate through a systematic, routine, and ordered array of observing books or unbound sheets of paper.