This firm made grinding machines, gun boring machines, metal-spinning lathes, and wood lathes, among other products. They were established in about 1869 by R. I. Costain and Nicholas B. Hadley as Hadley & Costain, "manufacturers of the Diamond Emery Wheel". They were also sellers of the grinder heads made by American Twist Drill Co., another Providence firm that was partly owned by Nicholas B. Hadley.

By 1881 the name had changed to the Diamond Emery Wheel & Machine Co. In 1889 or '90 the name changed again, to the Diamond Machine Co.. The firm incorporated in 1894 and remained in business until at least 1926.

Advertisement from the January 1896 "Machinery" magazine

Information Sources

• A Youtube.com video of a gun barrel borer and rifler from this maker shows a machine of remarkable mechanical automation.
• Various issues of Manufacturer & Builder mention this company. Issues are available through the Cornell "Making of America" archive.
• The Boston Directory for 1873, Sampson, Davenport & Co., lists "Hadley & Costain, Providence, R. I." as emery wheel manufacturers.
• On May 28, 1874, the Rhode Island General Assembly passed legislation to incorporate the American Twist Drill Company. John Worrall, Thomas H. Worrall, Nicholas B. Hadley, and B. H. Hadley were named. The company was established "for the purpose of manufacturing twist drills, solid emory wheel machinery, and for other manufacturing and mechanical business".
• Commerce, Manufactures & Resources of Providence, R.I, 1882, has the following writeup of this firm:

  "DIAMOND" EMERY WHEEL AND MACHINE CO.,

  Manufacturers Of Emery Wheel, Machinery And Tools, Grinding Machinery, Diamond Solid Emery Wheels, Beverly Street, Corner Of Mason And Aborn.

  Providence has long held a pre-eminent reputation as a manufacturing center, and there are certain enterprises carried on here which cannot be regarded as of secondary importance to the growth and prosperity of the city in an industrial sense. Of such concerns as are entitled to consideration, and would naturally be suggested by the above remark, the "Diamond* Emery Wheel and Machine Co. must not be forgotten.

  Established about thirteen years ago, and growing from year to year, the founders and proprietors paying more attention to the excellence of the wares manufactured than the amount or monetary returns, this company has now reached a place in the industrial community excelled by none.

  The present plant of the firm is located on Beverly street, as above indicated, and occupies a superficial area of about 7,000 square feet. Fifty operatives, moat of whom are experts in the working of steel and iron, are engaged here, while the machinery, which is in many respects novel, ingenious and unique, is operated by steam power; it's all new and of the most improved patterns, one hydraulic press, having a power of 560 tons pressure to the square inch, which is used in the manufacture of Emery Wheels.

  The products of this house consist of special tools and machinery, the latter for running emery wheels upon; they have many improvements and inventions of their own which has increased the demand and sale of these machines, beyond their most sanguine expectations.

  The proprietors of the company are Messrs. Benj. H. and George A. Hadley, the former of whom has been an inventor and designer of machinery for upwards of forty years and is widely known throughout the country as a practical and capable mechanic. He has given attention to the manufacture of Emeyy Wheel Machinery; their production is now superior to anything heretofore placed upon the market. That he has succeeded in this object is no matter of doubt, and the excellence the company have acquired in the production of their specialties is such as to have created a demand from the nearest as well as the most remote points of the United States, Canadas and Europe.

  As before remarked, their Emery Wheels may be relied upon to do the best work, they contain a larger percentage of pure emery than any other wheels made, and are guaranteed in every respect. A diamond pointed tool for turning up emery wheels is another specialty to which this house pays particular attention. This tool consists of a Pure Carbon or Black Diamond, set firmly in the end of a steel rod with a suitable wooden handle. An emery wheel so hard that it will cut the hardest file in two in a few moments, will at the same speed be cut to pieces by one of these diamond pointed tools. In all the products of this house superior excellence has been the only standard, and in their manufacture perfection has been as nearly accomplished as is possible to arrive at.

  The standing of the "Diamond" Emery Wheel and Machine Co., is so well-known as to need no commendation at our hands, suffice it to say that they have acquired a reputation of which they may be justly proud, and for which they are entitled to the highest esteem and consideration. Illustrated descriptive circulars will be forwarded upon application.

• June 1883 article on "Emery grinding machine". Looks somewhat like a bench grinder.
• August 1884 article on "Improved grinding machine"
• October 1884 article on "Improved lever and screw feed lathe"
• January 1885 article on "Improved lever and screw feed lathe". Pic clearly shows a wood-lathe version.
• May 1885 advertorial: "The Diamond Emery Wheel & Machine Co., of Providence, R. I., manufacture bench, foot and power lathes and the Diamond solid emery wheel in new and improved designs. They also make Hadley's patent counter shaft and belt shifter."
• The 1890 Railroad, Telegraph and Steamship Builders' Directory has listings for
  • Diamond Emery Wheel & Machine Co., 48 S. Canal st., Chicago, Ill.
  • Diamond Emery Wheel Co., Providence, R. I.
  • Diamond Machine Co., 48 Aborn st., Providence, R. I.
• The 1896-01-04 issue of Electrical World has the following writeup:

  The Diamond Machine Company, of Providence, R. I., was founded in 1883 by the late Benj. H. Hadley. At that time the title of the firm was the Diamond Emery Wheel & Machine Company, and this continued to be the firm name until the present concern was incorporated June 1,1894. After a fire, which consumed the larger part of the books, drawings, photographs, machinery, etc., of the company, a plot of ground about five acres in area was purchased on Atwell's Avenue, near Valley Street, and bordered by the Woonasquatucket River. On this lot a three-story brick building, 20S feet long and 60 feet wide, and several other smaller buildings were erected, which are equipped with the latest and most improved machinery of all descriptions, for the rapid and economical manufacture of the machines made by the company, an electric light plant, elevators, traveling cranes, etc. The shop is one of the best lighted in the city, and is in many respects a model establishment. It is the largest manufactory exclusively devoted to the making of grinding and polishing machinery in this country, if not in the world At first only a few sizes of plain grinding machines were made and the catalogue of 1886 shows seven styles only; it is a modest pamphlet of about 20 pages. The present catalogue of grinding machinery alone contains 64 pages, illustrating more than 40 different machines for grinding of various descriptions. These machines include plain grinders, water tool grinders, punch and die grinders, universal grinders and many others. From time to time a line of polishing and buffing machinery was added to the other productions of the firm, as well as a large variety of speed lathes, which as well as grinding and polishing machinery contain many valuable patented features, and the complete catalogue contains 180 pages, showing more than 100 different patterns of machines. The firm has agencies in various parts of the country, and is represented 'by strong firms in London and Germany. The productions of the concern have gradually found a way on account of their merit to foreign countries, and the trade with South Africa and South America is increasing.

• A posting in an owwm.org forum has pictures of a Diamond Emery Wheel & Machine Co. lathe. Another thread has a discussion about another lathe and about the company as well.
• The 1898 Directory of Rhode Island Manufacturers, published by the Providence Board of Trade, lists this company as a maker of bicycles, general machinery and tools.
• According to http://gorton-machine.org:8080/machines/index.html, The Geo. Gorton Machine Co. (Racine, WI) line of surface grinders was sold to Diamond Machine Co. in 1903. The line included disc sanders and engraving machines.
• The Henry Ford Museum has some ephemera from this company:
• Bulletin on "The Diamond face grinding machine : oil drive type", 1935
• "The 'Diamond' face grinding machine : 18-inch wheel", 1923
• "The 'Diamond' face grinding machine 54-inch wheel.", 1923
• "The 'Diamond' face grinding machine : 30 inch wheel", 1924
• "Diamond wet tool grinding machines", 1926