Ennion Williams (1752–1830), merchant, educator, and surveyor, was born near Philadelphia. He was a major in Samuel Miles’s Pennsylvania Rifle Regiment, 1776–77. By 1783 Williams had relocated to Berks County, where he operated a general store and sold real estate. In 1810 he received a patent for a protractor, and from then until at least 1815 he taught at his own academy and at other schools in the vicinity of Philadelphia. His publication of Ennion Williams’s Highly Improved Commercial Tables, of Foreign Weights, Measures, and Coins, Reduced to the Standard of the United States, and of Interest and Commissions (Philadelphia, 1823), led to a newspaper controversy with John Rowlett, who claimed that the work infringed on his own copyright. By 1823 Williams was living in Philadelphia and working as a surveyor and scrivener. When he died in that city, an obituary described him as the “late County Commissioner” (Hinshaw, Quaker Genealogy description begins William Wade Hinshaw and others, Encyclopedia of American Quaker Genealogy, 1936–50, repr. 1969–77, 6 vols. description ends , 2:827; “The Williams Family,” Pennsylvania Magazine of History and Biography 10 [1886]: 111; William Henry Egle, ed., “Journal of Major Ennion Williams, on His Journey to the American Camp at Cambridge, in New England. 1775,” Pennsylvania Archives, 2d ser. [1893], 15:5–20; Heitman, Continental Army description begins Francis B. Heitman, comp., Historical Register of Officers of the Continental Army during the War of the Revolution, April, 1775, to December, 1783, rev. ed., 1914, repr. 1967 description ends , 594–5; Peale, Papers description begins Lillian B. Miller and others, eds., The Selected Papers of Charles Willson Peale and His Family, 1983– , 5 vols. in 6 description ends , 1:201; Philadelphia Pennsylvania Packet or, the General Advertiser, 24 June 1783; Philadelphia Pennsylvania Journal, and the Weekly Advertiser, 23 Aug. 1783; List of Patents description begins A List of Patents granted by the United States from April 10, 1790, to December 31, 1836, 1872 description ends , 78; Philadelphia Poulson’s American Daily Advertiser, 14 July 1810, 1 Apr. 1811, 27 Mar. 1815; Washington Daily National Intelligencer, 7 May 1822; Caution to Banks, Merchants, &c. and An Appeal to the Public whether certain pen-marked, half-formed, spurious interest tables, unjustly published by Ennion Williams, should be discountenanced and condemned as a private injury or a public wrong; being the details of a controversy between John Rowlett & Ennion Williams, Chiefly as it appeared in several Philadelphia Newspapers in the 11th and 12th Months, 1823 [Philadelphia, 1823]; Robert Desilver, The Philadelphia Index, or Directory, for 1823 [(Philadelphia, 1823)]; Philadelphia Mechanic’s Free Press, 13 Feb. 1830).

A nonius is “a device consisting of a series of concentric arcs engraved on a quadrant, used for the accurate measurement of angles, altitudes, and heights” (OED description begins James A. H. Murray, J. A. Simpson, E. S. C. Weiner, and others, eds., The Oxford English Dictionary, 2d ed., 1989, 20 vols. description ends ).