Dwight Slate was a mechanic and engineer who developed a series of products for metal-working and ultimately founded his own company to make drills, grinders, and chucks.

Information on Slate's early career is sparse. He seems to have worked for Pratt, Whitney & Co. for a time. In late 1881 he was granted a patent for a lathe chuck, which was manufactured by the newly incorporated E. Horton & Son Co. Ezra Brewster Bailey was secretary and treasurer for a time, and later became secretary, treasurer, and general manager. Bailey also invested in Dwight Slate, who had started manufacturing milling machines and drills. Within a few years Slate had incorporated as Dwight Slate Machine Co., with Bailey as one of his directors. The company's assets were sold at auction in January 1913, although apparently some remnants of the company existed until 1915. In 1916 a Dwight Slate marking machine was being made by Noble & Westbrook Manufacturing Co. of Hartford.

Information Sources

• The February 1882 issue of Manufacturer & Builder carries a report on some recent inventions.

  Fig. 2 represents certain improvements in lathe chucks patented by Dwight Slate, of Hartford, Conn., who assigns his invention to the well known E. Horton & Son Co., of Windsor Locks, Conn. This invention relates to that class of combination chucks—that is, those which may be changed from universal to independent, and vise versa—which have an annular gear for engaging with pinions on the various screws which operate the jaws and a loose ring back of the annular gear for use in meshing and unmeshing the annular gear from such pinions. The improvement is a device different from those which have preceded it for causing the meshing and uneshing of said annular gear and said pinions. This invention consists substantially in the combination of the annular gear f, the loose ring g, provided with recesses h, and the radial slot i, the chuck body half b, provided with cams h', and the slot n, together with the disk l provided with the operating button and crank pin and springs o.

• The October 1883 issue of Manufacturer & Builder carries a report on exhibitors at that year's New England Manufacturers' and Mechanics' Institute Fair, including "from Dwight Slate of Hartford, Conn., his milling machines and sensitive drills".
• Seen on the web: 1895 catalog of the Dwight Slate Machine Co., 124 pages, showing chucks, drills, and grinders.
• The Illustrated Popular Biography of Connecticut, published 1891, mentions that Ezra Brewster Bailey was on the board of Dwight Slate Machine Co.
• From the March 1913 issue of Steam

  The business of the Dwight Slate Machine Company, Hartford, Conn., together with the complete equipment, was sold at auction January 16.

• From the website of the Library of the University of Vermont is a listing of holdings related to The Eagle Square Manufacturing Co.: "Carton 23 / Folder 26 / Correspondence #213, Dwight Slate Machine Co. / 12/04/1906 - 10/29/1915".