George Graham

Graham, George, 1674?–1751, English instrument maker. A clockmaker by trade, Graham designed clocks and watches that earned him membership in the Royal Society and were still manufactured into the present century. In 1725 he built a very accurate 8-ft (2.4-m) quadrant for the royal astronomer, Edmund Halley, at Greenwich; it was widely copied. His most important invention remains the micrometer screw, which enabled him to build zenith sections and calipers of unprecedented precision. Graham is buried in Westminster Abbey.

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

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