Instrumentation of the nineteenth and early twentieth centuries

Abstract

The régimes of Pond, Airy and Christie at the Royal Observatory, Greenwich, covered a century of rapid progress in physical astronomy high-lighted by pioneer activities in astronomical spectroscopy and astronomical photography. The Observatory's work consequently underwent considerable enrichment and extension, although emphasis continued to be placed on increased precision in fundamental astronomy and time-keeping. Observational accuracy depended heavily on the craftsman's ability to provide the necessary apparatus, the astronomer's expertise in tracing errors of instrumental adjustment and formulating appropriate corrections, and craftsman-astronomer co-operation to effect improvements and tackle new problems. Thus E. Troughton collaborated with Pond on the operation of a new mural circle and transit telescope, W. and J. Simms and C. May translated Airy's designs into instrumental realities, and H. Grubb worked closely with Christie on the replacement 28-inch refractor, the testing of photographic objectives, and trial runs with large astrographs. Airy's flair for optical engineering, coupled with the factory resources of Ransomes and May and Troughton and Simms, led to the acquisition of an altazimuth telescope, the now-famous transit circle astride the prime meridian, and the “Great Equatorial” with its Merz objective. Christie, as Chief Assistant, developed routine programmes in the measurement of double stars and determination of stellar radial velocities. Later, as Astronomer Royal, and with equatorials provided by Grubb, he steered the Observatory in the ambitious Carte du Ciel project, thereby paving the way for the photographic determination of stellar parallaxes and proper motions.