This is not the report of my own research, but the note of my lecture delivered at the meet ing of the Tokyo branch of the Society.Of many actions of ultraviolet rays and their appl ications, I presented a survey of the following articles:
1 The meaning of the term“ultraviolet rays.”
2 Discovery of ultraviolet rays.
3 Chemical actions of ultraviolet rays.
4 Fluorescence and phosphorescence of ultraviolet rays.
5 Photoelectric effect of ultraviolet rays.
6 Measurement of intensity of ultraviolet rays.
7 Absorption and diffusion of ultraviolet rays.
8 Reflecting power of ultraviolet rays.
9 Sources of ultraviolet rays.
10 How to separate the ultraviolet rays from visible radiation.
11 Bactericidal action of ultraviolet rays.
12 Stimulating action of ultraviolet rays.
13 Effects of ultraviolet rays upon the growth of plants.
14 Sunlight bath and sunlight therapy.
15 Quantity of ultraviolet rays of sunlight on the high mountains.
16 Light sensitiveness of human eyes in the dark places.
17 Application of ultraviolet rays in testing materials.
18 Microscopy with ultraviolet rays.
19 Do the ultraviolet rays produce injury to the human eyes.?

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The present paper is a lecture about the control of light.General idea of the control is delivered.

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The temperature coefficients of thermal expansion of the various heating wires are measured by a high temp.dilatometer from room temperature up to 1000°C.They are nearly constant at all the temperatures tested, and have the values from 1.92×10^-5 to 2.135×10^-5.

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