Refractor by J. Dollond(?)

Refractor by John Dollond. 42-inches focal length.
This refractor was used by Dr. J. A. Hamilton to make a series of measures of the Sun's apparent diameter in 1794-95, in order to test the relative accuracy of a wire-micrometer and an object-glass micrometer (both by Dollond). See Trans. Roy. Irish Acad., 10, 109-117.

Last Revised: 2009 November 18th