Abstract
I HAVE first to apologise for the very informal character of the communication which I am about to make to the club; I have not been able to put anything down upon paper, but I thought it might be interesting to some to hear an account of experiments that have now been carried on at intervals for a considerable series of years in the reproduction—mainly the photographic reproduction—of diffraction gratings. Probably most of you know that these consist of straight lines ruled very closely, very accurately, and parallel to one another, upon a piece of glass or speculum metal. Usually they are ruled with a diamond by the aid of a dividing machine; and in late years, particularly in the hands of Rutherfurd and Rowland, an extraordinary degree of perfection has been attained. It was many years ago—nearly twenty-five, I am afraid—that I first began experiments upon the photographic reproduction of these divided gratings, each in itself the work of great time and trouble, and costing a good deal of money. At that time the only gratings available were made by Nobert, in Germany, of which I had two, each containing about a square inch of ruled surface, one of about 3000 lines to the inch, and the other of about 6000. It happened, accidentally, that the grating with 3000 lines was the better of the two, in that it was more accurately ruled, and gave much finer definition upon the solar spectrum; the 6000-line grating was brighter, but its definition was decidedly inferior; so that both had certain advantages, according to the particular object in view.
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The Reproduction of Diffraction Gratings1. Nature 54, 332–333 (1896). https://doi.org/10.1038/054332a0
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DOI: https://doi.org/10.1038/054332a0