On the Earth we see and touch crowds of molecules every particle of which could be neither seen with our eyes nor felt with our touch nor perceived with any of our senses. And yet one meets very often so-called scientific men in the world who say peremptorily: “I only believe what I see.”
A large number of different measurements of the speed of light agree in proving that this speed is 186,000 miles a second. That is a fact of observation absolutely proved by astronomy and by physics.
These 186,000 miles amount to 982 million feet or 11,785 million inches.
Now, certain measurements of the same degree of precision show that in a ray of red light there are 42,300 waves to the inch or 1,666 to the millimetre.
Each of these waves therefore measures 6/10,000 of a millimetre. Those of the extreme red measure 7/10,000; beyond the red, wave-lengths of 8 or 9/10,000 are found; the blue waves measure 4 to 5/10,000 and the violet 4/10,000.
Expressed in millionths of a millimetre, as is usual in spectroscopy, these wave-lengths are the following:—
WAVE-LENGTHS OF LIGHT
| Infra-red | 900 or more |
| Extreme-red (A) | 760 |
| Red (B) | 687 |
| Orange (C) | 666 |
| Yellow (D) | 689 |
| Green (E) | 617 |
| Blue (F) | 486 |
| Indigo (Q) | 431 |
| Violet (H) | 897 |
| Ultra violet | 380 and less |
(These figures are those of the solar spectrum, measured for the first time by Frauenhofer a century ago.)
Those are waves in the ether, which is in perpetual movement.