Sketching the nebulae

Abstract

In recent years, many historians of science have turned their attention to the visual culture of science. However, the value of images within the practice of science -- even within a highly visual discipline like astronomy -- remains incompletely understood. No one disputes that astronomers use images to communicate with their scientific peers and the broader public or that images can shape and influence the questions astronomers ask. But getting at precisely how visual representations contribute to the acquisition of knowledge and insight is a harder task. In his study of nineteenth-century drawings of nebulae and the procedures adopted by the observers who made them, Omar W. Nasim has done exactly this.Nasim's subject lends itself well to this issue. For nineteenth-century observers, the uncertainty of the nebulae created a vexing problem. These clouds of glowing light could not be measured and quantified in the manner of other celestial objects. Their history, structure, and makeup were all up for debate. As Nasim convincingly demonstrates, the act of drawing became a means to discern the very nature of the nebulae.To make his case, Nasim attends closely to a body of images that have not been carefully analysed: drawings in the observing books of scientists. Observing by hand reproduces numerous pages from these personal record books; the illustrations make evident Nasim's research skills and the pleasure he derives from archival discoveries. At first glance, it is easy to see why historians have largely looked past such sketches. Rough and often tiny, wedged between columns of numbers and scribbled notes, they appear rushed, insignificant, and idiosyncratic. But Nasim ably guides the reader to their salient features, reconstructs the processes used by the observers who made them, and reveals the epistemological value of these sketches both to their creators and to historians who strive to understand scientific practice.The first two chapters consider the work of Lord Rosse and his assistants using the Leviathan, as well as the broader response and interpretation of their observations. Nasim tells a new story about this famous reflector by focusing on the recording methods put into place, in particular, the practice of copying personal drawings into a shared ledger book as a means to synthesize and consolidate the diverse observations made by the many eyes and hands that used the Leviathan. This collection of drawings, made over many years, aided and enhanced the process through which observers became familiar with the nebulae. Nasim also introduces two terms to describe the qualities of the Rosse drawings. He argues that the project initially made portraits of the nebulae, drawings that concentrated on morphological features; later, due to pressure from the astronomical community, the project shifted its attention to descriptive maps, drawings that integrated the pictorial features of the nebulae with numeric data and that necessitated the development of a new procedure. …