Part 30

A. Lamb & Son (fl. late 18th century); mathematical instruments.

Anthony Lamb (1703-1784); mathematical instruments.

John Lamb (1735-1800); mathematical instruments.

M. Morris (fl. 1785); protractors.

Widow Balthaser Sommer (fl. 1753); optical instruments.

Charles Walpole (fl. 1746); mathematical instruments.

James Youle (1740-1786); surgical instruments.

John Youle (fl. 1786); surgical instruments.

OHIO

Columbus: Augustus Platt (1793-1886); mathematical instruments.

Benjamin Platt (1757-1833); surveying instruments and clocks.

Gallipolis: Joseph (fl. 1792) and Francois Devacht; watches, compasses, and sundials.

PENNSYLVANIA

Bucks County: W. L. Potts (late 18th century); surveying instruments.

George Wall, Jr. (fl. 1788); surveying instruments.

Germantown: Christopher Sower (c. 1724-1740); mathematical instruments and clocks.

Christopher Witt (fl. 1710-1765); mathematical instruments and clocks.

Harrisburg: Frederick A. Heisely (1759-1839); clocks and mathematical instruments.

George Heisely (1789-1880); clocks and mathematical instruments.

Lancaster: George Ford (late 18th century to 1842); surveying and nautical instruments.

George Ford II (fl. 1842); surveying and nautical instruments.

Frederick A. Heisely (1759-1839); clocks and mathematical instruments.

George Hoff (1740-1816); clocks, surveying instruments.

Thomas Mendenhall (fl. 1775); mathematical instruments and clocks.

Norristown: David Rittenhouse (1732-1796), practitioner; astronomical and surveying instruments.

Philadelphia: Owen Biddle (1737-1799), practitioner.

Thomas Biggs (fl. 1792-1795); surveying instruments.

Isaac Brokaw (fl. 1771).