Inventors at work, with chapters on discovery (1906)
Iles, George, 1852-1942 · New York, Doubleday, Page & company · leaf 128
an auger takesits way through a plank itremoves as chips all thewood within the circle ofits range; a drill, of com-mon form, as it piercesstone or metal acts in asimilar manner. Motivepower is greatly econo-mized when a drill is tubu-lar, with the further ad-vantage that within thering cut a solid… … 92 FORM—DRILLS fields, or to the geologist who reads at a glance the compositionof a mineral, the forces which have impressed it age after age.Such drills, set with bortz diamonds, have accomplished remark-
Inventions · Inventors
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![An illustration from [Electric engineering.] (1902)](https://img.insideoutlibrary.com/img/200/ia-electricengineer01inte-97-24.webp)
