Among the early makers of mathematical instruments in Philadelphia was William Dean (?-1797), who is believed to have been working in that city as early as 1778. His name first appears in local directories in June 1792, where his shop address was listed as No. 43 South Front Street. Later he advertised that he made and sold "Surveying instruments--Telescopes, Sextants, Quadrants--and every article requisite for navigation, surveying, levelling, &c...." According to details which were noted in his last will, which was dated June 1, 1797, and filed and proved in the following month, Dean's death appears to have been preceded by a long illness. He designated his two sisters as his executrices, and the fact that his will specified the appointment of a Mr. Thomas Yardley, Jr., as guardian of his three children indicates that he may have been a widower at the time of his death. A surveying compass by this maker was recently brought to light in, the Clark County Historical Society, Springfield, Ohio, by Dr. Donald A. Hutzlar of the Ohio State Museum. The instrument is a plain compass in brass without levels, 13-1/2 inches in length, and with a 5-inch needle. The dial is marked "DEAN PHILAD^a." The wooden cover for the instrument is marked with the names of previous owners and dates, as follows: Jno. C. Symes, Aug. 10, 1778 I. Ludlow, 1791 Henry Donnel, July 24, 1794 Jonathan Donnel, 1796 John Dyherty Thomas J. Kizer, 1838 David J. Kizer, '78. A description of this instrument in "_The History of Clark County, Ohio_" by A. P. Steele, published in 1881 by the W. H. Beers Co. of Chicago, adds considerably to its interest as a historical record of American scientific instruments and their use: "Col. Thomas Kizer, the veteran surveyor, has in his possession a compass made by Dean of Philadelphia; this instrument was owned and used by his father, David Kizer, who obtained it from John Dougherty about 1813; Dougherty got it from Jonathan Donnel. This relic is marked I. Ludlow, 1791; Henry Donnel, 1794; J. Donnel, 1796, John Dougherty, 1799; these marks are rudely scratched upon the cover of the instrument, and bear every evidence of being genuine; there is no doubt but that this old compass was used in making the first surveys in this county, or that it is the identical instrument used by John Dougherty, in laying off Demint's first plat of Springfield, and by Jonathan Donnel on the survey of 'New Boston.'" It is to be noted that some discrepancies exist in the listing of names and dates of the previous owners between Steele's _History_ and those which actually appear on the cover of the instrument. Steele apparently made the changes he deemed necessary in his account of the instrument.