Christiaan Sterken
In 1871, the Belgian astronomer Jean-Charles Houzeau developed a new approach to determine the solar parallax. His "heliometer with unequal focal lengths" produces a large and a small solar image, as well as a large and a small image of Venus. Making the small solar and the large Venus image coincide yields a measure of the angular distance of the centers of both objects. Two such instruments were built for two Belgian expeditions to observe the Venus transit of December 6, 1882: one to San Antonio, Texas, and another one to Santiago de Chile. These were the first major expeditions in the history of Belgian science. This paper documents the expeditions, and clarifies the principal instrument and its present-day whereabouts.
Manuscript: jad19_1q.pdf