In 1893 Azariah Yeldon Pearl, of West Lebanon, New Hampshire, patented an auger for drilling square holes. It used an auger bit rotating inside a square housing; in addition, a small horizontal shaft near the bottom of the housing turned a pair of relatively thick cutters, one each on opposite faces of the square, and each with diameter equal to the length of the side. They were manufactured by the inventor's company, the Pearl Square Auger Manufacturing Co. As complex as it was, this auger would not qualify for listing on this Vintage Machinery site. But Pearl also manufactured hand-powered boring machines to drive his mortising augers, and those boring machines do qualify.

A series of subsequent patents covered improvements to his auger, to reduce heat buildup, improve chip evacuation, make it easier to extract the auger from the hole, and simplify the mechanism. Despite the simplifications these augers must have been quite expensive. They were also impractical in smaller sizes and the main customers were builders of railcars.

A 1907 patent covered an improved machine for driving the square-hole augers, and we presume that he manufactured this improved machine as well.

Information Sources

• 1894 Proceedings of the Fourth Annual Meeting of the American International Association of Railway Superintendents of Bridges and Buildings, held in Kansas City, Mo., October 16-18 1894 has a full-page from the Pearl Square Auger Mfg. Co., 24 Kingston St., Boston, Mass. "The Pearl Square Auger is the only auger that bores a square hole or mortise. it is adapted for car, pilot, and cab work, mortising for locks, frame buildings, and every place where mortising is required." It was available in hand auger and power auger versions.
• 1895 Proceedings of the Fifth Annual Convention of the Association of Railway Superintendents of Bridges and Buildings, held in New Orleans, La., October 15-16 1895 has a full-page from the Pearl Square Auger M'f'g. Co., Rochester, N. H. A simple belt-powered horizontal mortiser is shown, along with an image of the power auger version of the square hole auger. "Send for Catalogue of Upright Mortising Machine."
• 1896 New England Business Directory has an illustrated ad for the Pearl Square Auger Mfg. Co. of Rochester, N. H. "Factory at Gonic, N.H." "Manufacturers of the Pearl Square Auger, and Round Augers / of every description. / Also / Both hand & power boring machines." The directory listing reads, "PEARL SQUARE AUGER MFG. CO., Rochester. Inc. 1893. A. Y. Pearl, Pres. Harry V. Moore, Sec. M. O. Hall, Treas."
• August 1905 The Engineer, a British journal, describes the Pearl square auger and notes that machines to drive it are manufactured by the Pearl Square Auger Manufacturing Co. of New York.
• British broadside for the Pearl Square Auger, made in Rochester, New Hampshire by the Pearl Square Auger Manufacturing Company of New York. It could be powered by a hand-cranked mortiser or by a belt-driven machine. The British distributor was Messrs. Thos. Thompson and Co., of 35, New Broad-street, London.
• June 2010 CRAFTS New Jersey "The Tool Shed" newsletter (PDF), page 6, has an illustrated article by Frank Kosmerl on the Pearl auger bit.
• A UKWorkshop.co.uk forum discussion provides some key information on this maker. Thanks to Geoff Emms for forwarding the information to us via email.