Tyndall, however, states in all frankness, and without the aid of mathematical considerations, that “when we try to visualize the motions of the air having one thousand separate tones, to present to the eye of the mind the battling of the pulses, direct and reverberated, the imagination retires baffled at the attempt;” and he might have added, the shallowness and fallacy of the wave theory of sound was made apparent.  He, however, does express himself as follows:  “Assuredly, no question of science ever stood so much in need of revision as this of the transmission of sound through the atmosphere.  Slowly but surely we mastered the question, and the further we advance, the more plainly it appeared that our reputed knowledge regarding it was erroneous from beginning to end.”

Until physicists are willing to admit that the physical forces of nature are objective things—­actual entities, and not mere modes of motion—­a full and clear comprehension of the phenomena of nature will never be revealed to them.  The motion of all bodies, whether small or great, is due to the entitative force stored up in them, and the energy they exercise is in proportion to the stored-up force.

Tyndall says that “heat itself, its essence and quiddity, IS MOTION, AND NOTHING ELSE.”  Surely, no scientist who considers what motion is can admit such a fallacious statement, for motion is simply “position in space changing;” it is a phenomenon, the result of the application of entitative force to a body.  It is no more an entity than shadow, which is likewise a phenomenon.  Motion, per se, is nothing and can do nothing in physics.  Matter and force are the two great entities of the universe—­both being objective things.  Sound, heat, light, electricity, etc., are different forms of manifestation of an all-pervading force element—­substantial, yet not material.

* * * * *

[NATURE.]

THE RELATION OF TABASHEER TO MINERAL SUBSTANCES.

Mr. Thiselton Dyer has rendered a great service, not only to botanists, but also to physicists and mineralogists, by recalling attention to the very interesting substance known as “tabasheer.”  As he truly states, very little fresh information has been published on the subject during recent years, a circumstance for which I can only account by the fact that botanists may justly feel some doubt as to whether it belongs to the vegetable kingdom, while mineralogists seem to have equal ground for hesitation in accepting it as a member of the mineral kingdom.

It is very interesting to hear that so able a physiologist as Prof.  Cohn intends to investigate the conditions under which living plants separate this substance from their tissues.  That unicellular algae, like the Diatomaceae, living in a medium which may contain only one part in 10,000 by weight of dissolved silica, or even less than that amount, should be able to separate this substance to form their exquisitely ornamented frustules is one of the most striking facts in natural history, whether we regard it in its physiological or its chemical aspects.