Artificial Light eBook

Matthew Luckiesh
This eBook from the Gutenberg Project consists of approximately 330 pages of information about Artificial Light.

Artificial Light eBook

Matthew Luckiesh
This eBook from the Gutenberg Project consists of approximately 330 pages of information about Artificial Light.

Scientists are becoming more and more intimate with the structure of matter.  They are learning secrets every year which apparently are leading to a fundamental knowledge of the subject.  When these mysteries are solved, who can say that man will not be able to create elements to suit his needs, or at least to alter the properties of the elements already available?  If he could so alter the mechanism of radiation that a hot metal would radiate no invisible energy, he would have made a tremendous stride even in the production of light by virtue of high temperature.  This property of selective radiation is possessed by some elements to a slight degree, but if treatment could enhance this property, luminous efficiency would be greatly increased.  Certainly the principle of selectivity is a byway of possibilities.

A careful study of commonplace factors may result in a great step in light-production without the creation of new elements or compounds, just as such a procedure doubled the luminous efficiency of the tungsten filament when the gas-filled lamp appeared.  There are a few elements still missing, according to the Periodic Law which has been so valuable in chemistry.  When these turn up, they may be found to possess valuable properties for light-production; but this is a discouraging byway.

It is natural to inquire whether or not any mode of light-production now in use has a limiting luminous efficiency approaching the ultimate limit which is imposed by the visibility of radiation.  The eye is able to convert radiant energy of different wave-lengths into certain fixed proportions of light.  For example, radiant energy of such a wave-length as to excite the sensation of yellow-green is the most efficient and one watt of this energy is capable of being converted by the visual apparatus into about 625 lumens of light.  Is this efficiency of conversion of the visual apparatus everlastingly fixed?  For the answer it is necessary to turn to the physiologist, and doubtless he would suggest the curbing of the imagination.  But is it unthinkable that the visual processes will always be beyond the control of man?  However, to turn again to the physics of light-production, there are still several processes of producing light which are appealing.

Many years ago Geissler, Crookes, and other scientists studied the spectra of gases excited to incandescence by the electric discharge in so-called vacuum tubes.  The gases are placed in transparent glass or quartz tubes at rather low pressures and a high voltage is impressed upon the ends of these tubes.  When the pressure is sufficiently low, the gases will glow and emit light.  Twenty-eight years ago, D. McFarlan Moore developed the nitrogen tube, which was actually installed in various places.  But there is such a loss of energy near the cathode that short “vacuum” tubes of this character are very inefficient producers of light.  Efficiency is greatly increased by lengthening the tubes, so Moore used tubes of great

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Project Gutenberg
Artificial Light from Project Gutenberg. Public domain.