have the external propagation, which presents none of the difficulties of its predecessor.
Nor can we pass this stage without calling attention to the startling conclusion to which this external propagation leads.
8. Singular surfaces are wave surfaces.
It is shown that the matter of the molecules passes freely through the medium or vice versâ. What does this imply?
That the singular surface has all the characteristics of a wave boundary.
If the medium is stationary and the molecules are moving with the earth, the grains within the surfaces do not partake of the mean motion of these surfaces, being continuously replaced by other grains by the action of propagation, by which the singular surfaces in their motion are continually absorbing the grains in front and leaving those behind without any mean effect on the motion of the grains. And thus there is perfect freedom of motion of the molecules or aggregate matter, although the grains which constitute the nuclei are changing at the rates expressed by 20 miles a second.
To be standing on a floor that is running away at a rate of 20 miles a second without
