Exp Astron (2009) 25:79–89 DOI 10.1007/s10686-009-9138-9 REVIEW ARTICLE “Beautiful and cantankerous instruments”: telescopes, technology, and astronomy’s changing practice W. Patrick McCray Received: 5 January 2009 / Accepted: 6 January 2009 / Published online: 3 February 2009 © Springer Science + Business Media B.V. 2009 Abstract Between the dedication of the 200” Hale Telescope in 1948 and the completion of today’s 8–10 m behemoths, astronomers’ most iconic symbol, the telescope itself—its design, its technology, and its use—was transformed as a research tool. The importance of this is deceptively simple: in astronomy, technological innovations have often led to new discoveries. Driven by the need to get as much observing time as possible and the desire to take advantage of the best observing conditions, modern observatories have experimented with new technologies and modes of collecting images and spectra. This entailed a re-casting of the telescope by astronomers and science managers as a factory of scientific data. At the same time, contemporary astronomers express considerable unease and apprehension about how these technological changes have altered, in ways subtle and profound, the nature of astronomical observing and what it meant to be an astronomer. This short essay addresses the issues associated with these recent changes in astronomical practice and their connections to astronomers’ desire for ever larger and more complex telescopes. Keywords Telescope history · Practice of astronomy · Giant telescopes 1 Introduction Eight years ago, I visited Cornell University. There, in the Astronomy Department, I found a sign in a hallway that read: “Know Thyself. Know Your Telescope.” This adage, paraphrased from Socrates, says a good deal about W. P. McCray Department of History, University of California, Santa Barbara, Santa Barbara, CA, USA e-mail: pmccray@history.ucsb.edu