Thomas Jones (1775-1852) learned the instrument trade from Jesse Ramsden in London,
and was elected a Fellow of the Royal Society of London in 1835. This theodolite--a very early
example of a transit theodolite--is one of several instruments that he made for the United States
Coast Survey in the 1840s. The horizontal and vertical circles are silvered, and read by verniers
and magnifiers to 30 seconds.
Ref: Gloria Clifton, Directory of British Scientific Instrument Makers 1550-1851 (London,
1995), p. 154.