Figure 10. — Transit and equal-altitude instrument (left) made by EUicott in 1789 

 and used by him in the survey of the boundary between the United States and 

 Florida and in other surveys. USNM 152080. 



Figure 11. — Zenith sector with focal length of 6 ft., made by David Rittenhouse 

 and revised by Andrew Ellicott. Described in Journal of Andrew EUicott 

 (Philadelphia, 1803). USNM 152078. 



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