Abstract
THIS work forms a good practical text-book on the art of photometry, which, both scientifically and commercially, is becoming more and more important. It contains a comprehensive account of the various methods in daily use, so that the student, when he finds that he is dealing with instruments and methods unfamiliar to him, may turn to this book as a guide to the many precautions necessary to insure accurate results. The first few chapters deal with the history and principles of photometry, together with horizontal, radial, and jet photometers, and diagrams are given of the determinations of the quantity of light afforded in all directions horizontally by three classes of flames tested at every 10°, and also of Dr. Pole's method of expressing the illuminating power and rates of consumption per hour of fifteen-candle gas. In chapters vi. and vii. we have a discussion on the various standards of light which have been and are still in use, followed by the numerous proposed substitutes, such as Harcourt's pentane, Sugg's sixteen-candle argand, Methuen's screen, &c. The apparatus necessary to check and measure the flow of gas to the standard burner is given in chapter viii., with detailed descriptions. Chapters ix. and x. treat of “ The Examination and Adjustment of a Gas-testing Photometer” and “Colour Photometry,” the latter dealing with methods of estimating the colour and intensity of the illumination of fabrics, &c. Lastly, in chapter xi., on “Stellar Photometry,” the author gives an account of the methods employed by Sir John Herschel, Zöllner, and others, concluding with a description of a method proposed by himself.
Practical Photometry: a Guide to the Study of the Measurement of Light.
By W. J. Dibdin. (London: Walter King, 1889.)
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Our Book Shelf. Nature 40, 572 (1889). https://doi.org/10.1038/040572a0
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DOI: https://doi.org/10.1038/040572a0