manner a train of ether-waves to their source; remembering at the same time that your ether is matter, dense, elastic, and capable of motions subject to and determined by mechanical laws. What, then, do you expect to find as the source of a series of ether-waves? Ask your imagination if it will accept a vibrating multiple proportion—a numerical ratio in a state of oscillation? I do not think it will. You cannot crown the edifice by this abstraction. The scientific imagination, which is here authoritative, demands as the origin and cause of a series of ether-waves a particle of vibrating matter quite as definite, though it may be excessively minute, as that which gives origin to a musical sound. Such a particle we name an atom, or a molecule. I think the seeking intellect, when focussed so as to give definition without penumbral haze, is sure to realize this image at the last."
The import of these sentences is plain. It is that an ethereal or other atom, or a molecule, is related to its vibratory motion just as any ordinary body is related to its movements of translation—as a stellar or planetary body, for instance, is related to its movements of rotation or revolution; and that, just as the conception of the stellar or planetary body of necessity precedes the conception of its rotary or revolutionary motion, so also the conception of the atom or molecule of necessity precedes the conception of the vibratory motion whereof light, heat, electricity, chemical action, etc., are known or supposed to be modes. In other words: to make the existence of matter, such as we deal with in action and in thought, conceivable, we are constrained, according to Tyndall, to assume ultimate material particles as preexisting to those motions or manifestations of force which are apprehended as light, heat, electricity, chemical action, etc.
In order to preclude all possibility of misunderstanding, it is perhaps well to call attention to the fact that, while Tyndall speaks in terms only of the relation of the ether to its vibratory motion, it is evident from his own language that this is meant as an illustration or exemplification of the relation of all matter to any or all motion whatever.
Now, let us for a moment contemplate an ultimate particle of matter in this state of existence in advance of all its motion. It is without color, and neither light nor dark; for color, lightness, darkness, etc., are luminar affections, and, according to the received mechanical theory of "imponderables," of which Prof. Tyndall is a distinguished champion, simply modes of motion. It is similarly without temperature—neither hot nor cold; for heat also is a mode of motion. For the same reason it is without electrical or chemical properties—in short, it is utterly destitute of all those properties in virtue of which, irrespective of its magnitude, it could be an appreciable object of sense, unless we except the properties of weight and extension. But weight is a mere play of attractive forces; and extension, too, is known to us only as resistance, which in turn is a manifestation of force, and thus a phase of motion. Extension per se, abstract extension, cannot