Figure 3. — ^Transit telescope made by David Rittenhouse and used by him for 

 the observation of the transit of Venus in 1769. Brass, 33j^-in. tube on a 25- 

 in. axis, with an aperture of 1^4 in. and a focal length of 32 in. Photo courtesy 

 the American Philosophical Society. 



related records has revealed that only a few of the many clock- 

 makers working in the American Colonies in the 18th century made 

 mathematical instruments. Yet, a large proportion of the surviv- 

 ing surveying and nautical instruments produced before 1800 were 

 the work of clockmakers. Classic among these must be noted the 

 instruments produced by the brothers David and Benjamin Ritten- 

 house (see p. 15 and figs. 3 and 4), as well as the fine surveying 

 instruments made by four separate members of the Chandlee 

 family, whose clockmaking traditions began early in the 17th cen- 

 tury (see p. 54). 



11 



