McMaster, Hartson & Co. manufactured wooden-works clocks in Vienna, Ohio. The manufactory was located on a site, purchased by Dwight McMaster (born 1802) in February 1828, on the north side of Warren-Sharon Road east of Vienna Center. (The site is now occupied by Crown Hill Burial Park.)
McMaster was joined in this business by brothers David R. Hartson (born 1801) and William H. Hartson (born 1805). According to historian Rebecca M. Rogers, Vienna resident Thomas Merritt and businessman from Lorain County, Ohio, initially financed the venture through mortgages of $475, payable in clocks, and $600 in cash. Successful and influential Warren merchants David and Leicester King also invested $1,000 in the company.
The site had water power, so this company may have manufactured clock parts as well as assembled them. The company purchased clock parts from Ansel Merrell and from Lambert W. Lewis, whose factory stood across the road.
The business ceased as a clock manufactory in 1830, when it was converted to a carding mill.
Dwight McMaster and David R. Hartson moved to Elyria, Lorain County, Ohio. McMaster, Hartson & Co.'s debt led to Thomas Merritt's bankruptcy in 1832.
McMaster's and the Hartsons' careers as clock manufacturers mirrored in many respects those of other Vienna clockmakers. Overextension of credit through mortgages, reduced demand for clocks, and an economic depression in the early 1830s essentially ended the clockmaking "boom" in Vienna and Trumbull County.
Dwight McMaster's brother Schuyler appears to have been an employee of one of the clock factories in Vienna. Schuyler and his wife Lucy Hart lived about one-and-a-half miles north of Woodford's Corners on the east side of Sodom-Hutchins (now Hutchings) Road. (The house still stood in 1999.)
Rogers, Rebecca M. Trumbull County Clock Industry, 1812-1825. Dayton, OH : Sterling Graphics, [1991?].
 David R. Hartson married to McMaster's sister Thirza on February 18, 1826.
 Rebecca M. Rogers, Trumbull County Clock Industry, 1812-1825 (Dayton, OH : Sterling Graphics, [1991?]), p. 24.
 Fred L. Martin and James Bradley, "A Genealogical History of Vienna," in Vienna, "Where We Live and Let Live": Town 4, Range 2 of the Connecticut Western Reserve (Apollo, PA: Closson Press, 1999), p. 52.