In early 1858, William T. Nicholson and Isaac Brownell established a partnership, Nicholson & Brownell, to manufacture jewelers' tools and light machinery. The following year Brownell left the partnership and Nicholson continued the business as W. T. Nicholson. By the early 1860s he was making "rifle and milling machines for gunmakers", supplying the numerous Providence-area armament makers who were producing weaponry for use in the U.S. Civil War. In 1860 Nicholson manufactured Clark's Improved Vise invented by Charles B. Clark. Nicholson partnered with a Mr. H. A. Munroe, organizing as Nicholson & Co. That firm seems to have primarily manufactured parts for the Springfield rifle. In early 1864, with the Civil War at its peak, Nicholson patented a file-making machine, sold off his armaments-related business and went on to much greater fame and fortune as a file maker after incorporating as the Nicholson File Co. As of 2018, Nicholson remains one of the world's larger file makers, and the early foray into milling machines is virtually forgotten.

Information Sources

• The 1864 book A History of American Manufactures, from 1608 to 1860: Exhibiting, Volume 2, by John Leander Bishop.

  W. T. Nicholson is a prominent manufacturer of small Machinery, especially such as Jewellers and Silversmiths use, and latterly of Rifle and Milling Machines for Gunmakers. He is also the inventor of a Metallic Spirit Level, which is now found in many of the best machine shops, whose proprietors recommend it as far superior to the ordinary wooden level for accuracy and durability. The sides and edges being perfectly true, it combines with a Level a convenient and reliable Straight Edge. Mr. Nicholson is also the manufacturer of Clark's Patent Vise, which has all the advantages of the common parallel Castiron "Vise, besides the important additional one of holding taper as well as parallel forms, and being simple in its construction. These Vises are self-adjusting, and have a strong rib built up back of the swivel jaw to receive the strain from all directions. Mr. Nicholson has also recently patented a machine for making Files, and a large establishment for their manufacture is about going into operation.

• The 1886 book, The Providence Plantations for Two Hundred and Fifty Years, by Welcome Arnold Greene, has a good biography of Mr. Nicholson.