In 1841, after seeing the Ertel universal instrument at the Depot of Charts and Instruments
(soon to become the United States Naval Observatory), Father Curley determined to acquire a
similar instrument for Georgetown College (now University), where he served as professor of
mathematics and natural philosophy. Father Curley's quest for funds was successful, and within a
few years he was using "an Universal or Altitude and Azimuth Instrument, reading to 10 seconds,
by Ertel & Son, of Munich," to orient the walls and determine the position of the new
Georgetown College Observatory, and to determine the positions of several prominent sites in
Washington, D.C. The horizontal and vertical circles of this instrument are silvered, graduated to
10 minutes, and read by verniers and magnifiers to single seconds. There is a second telescope
below the horizontal circle.
Ertel & Sohn made the mechanical parts of the instrument. Traugott Leberect Ertel
(1778-1858) had joined the Mathematical-Mechanical Workshop in Munich around 1812 and
become its sole proprietor around 1820. It was probably he who designed this instrument. In
1834, when Georg Ertel (1813-1863) was taken into partnership, the firm began trading as Ertel
& Sohn. They exhibited a larger but still portable universal instrument at the Crystal Palace
Exhibition of 1851, and an "Instrument universel pour les observations astronomiques et
terrestres" at the Paris Exhibition of 1855. The Utzschneider u. Fraunhofer signature refers to the
Optical Institute that made the lenses for the instrument. Since Merz u. Mahler became
proprietors of the Optical Instrument in 1840, the Georgetown instrument might have been one
that had been in stock for some time.
Ref: Francis Heyden, "Astronomy at Georgetown College," Records of the Columbia
Historical Society 53-56 (1953): 155-172.
Annals of the Georgetown Observatory, vol. 1 (1852), p. 14.
Exhibition of the Works of Industry of All Nations, 1851, Reports by the Juries (London,
1852), pp. 250-251.