Abstract
THE presidential address of Mr. W. Taylor to the Institution of Mechanical Engineers on October 28 was mainly devoted to the application of mechanical engineering to the production of lenses, particularly photographic lenses, which to-day are made by the tens of thousands. One of the characters of mechanical engineering, he said, is the extraordinary accuracy regularly attained in its best products. One thousandth of an inch is approximately the limit of accuracy which can be attained in the ordinary machining of metal with cutting tools, one ten thousandth the order of accuracy by grinding and lapping; but in making the best photographic lenses and other optical instruments of precision, the accuracy of the surfaces of the elements, such as lenses, prisms and mirrors, must be from one hundred thousandth to a few millionths of an inch, and this accuracy is attained in everyday working, not only by skilled artist craftsmen, but also by less skilled persons doing repetition work by the aid of special appliances, the products of mechanical engineering. In tho course of his address, Mr. Taylor referred at length to the functions and designing of lenses, the properties and the production of optical glass and the various workshop processes by which lenses are cut, ground, polished and tested. It was in connexion with work on photographic lenses that the need was felt for screw-threads much more accurate in form, more free from pitch and periodic error, and this in turn led to improved technique of screw-thread measurement, gauging and generation.
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Manufacture of Lenses. Nature 130, 732–733 (1932). https://doi.org/10.1038/130732c0
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DOI: https://doi.org/10.1038/130732c0