Figure 4.—Surveying compass marked "Potts and Rittenhouse." Believed to be the work of David Rittenhouse in partnership with Thomas Potts. Photo courtesy the American Philosophical Society.
Finally, one must not overlook the fact that examples of English and other European instruments were available in the Colonies, and that at least some of the early colonial makers undoubtedly copied them. It is apparent from some surviving early American instruments that the materials, designs, dimensions, and details of European prototypes had been deliberately copied. It is possible to see in public collections, for instance, a Davis quadrant of English manufacture exhibited beside a later example, signed by a New England maker, which comes extraordinarily close to duplicating it in every feature.
As with the presumed influence of published works, the practice of copying imported instruments cannot be documented, but it must have been engaged in by many of the unschooled New England instrument makers. By this means some may even have profited to the degree that they became professional craftsmen without benefit of formal apprenticeship.
Yet it is remarkable that although numerous instruments were produced by native artisans, in addition to the substantial number which were imported before the end of the 18th century, relatively few specimens have survived in public collections as well as in private hands. Despite the exhaustive combing of attics and barns throughout the country by dealers in antiques and by avid collectors during the past several decades, the number of surviving instruments now known is incredibly small in comparison with the numbers known to have been made locally or imported before the beginning of the 19th century. Since instruments are not items which would ordinarily be deliberately discarded or destroyed, or melted down for the recovery of the metal, this small percentage of survival presents a puzzle which has not been resolved.
Figure 5.—David Rittenhouse. Engraving from portrait by Charles Wilson Peale.