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This instrument, C.I.W. No. 20, was manufactured by the Department of Terrestrial Magnetism of the Carnegie Institution of Washington. It was acquired by the Dominion Observatory prior to the 1907 field season, and was used until the late 1940s.
The instrument is of the “universal” type; that is, it can be used for measuring declination, inclination, horizontal intensity, and even total intensity, although the attachments necessary for the latter measurement were never acquired by the Dominion Observatory. The telescope on the side made it possible to take astronomical observations as well.