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that the magnifying of any object while in motion will exhibit that motion increased in velocity just as many times as the diameter of the object is augmented. Suppose we had at our command an instrument competent to amplify the atoms to the one-fiftieth of an inch in diameter: in the case of the hydrogen-atom the necessary magnifying power would be 10,000,000 diameters, under which power the atoms would have their motions enhanced by the same multiple, and we should then be called upon to examine an image the fiftieth part of an inch in diameter plunging across the field of vision five hundred million times faster than the flight of a cannon-ball.

It follows, since human skill is incompetent to penetrate by any mechanical means into the internal structure of matter, that we shall be compelled to direct our labors to other modes of investigation if we would know more of the atomic structure of matter, possessing as it does a minuteness far surpassing the analytical power of the microscope; in fact, so hopelessly ultra-microscopic as to elude all other processes except that of mathematics and experimental investigation.

The question of the infinitely large and the immeasurably small has engaged the attention of philosophers since the days of Democritus. Modern investigators are, however, in possession of experimental data that aid them in arriving at facts with ever-increasing accuracy. We have the atomic theory first placed upon a substantial basis by Dalton, which treats of the atomic constituents of matter, and gives to each atom a definite size and weight, and establishes the proposition that atoms combine to form molecules, and that molecules aggregate to masses. We have also the kinetic theory of gases, which has been placed upon a purely mathematico-scientific footing, as has also the department of hydro-kinetics; and experiments within these departments are accumulating evidence concerning the atomic and physical structure of matter.

The kinetic theories are based upon the conception that these particles or atoms are in constant motion among themselves; and it assumes, also, that their movements have an infinite series of velocities in all conceivable directions, but with varying degrees of intensity. This idea of atomic and molecular motion puts us in possession of an important factor for determining the causation of all physical phenomena. Of course we do not presume to say that the atom is the primordial or ultimate constituent of matter, for there are many evidences to show that the present list of sixty-five elements of matter may not be elementary at all, but isomeric compounds of one or more simpler constituents.

The question might here be asked, "How does the physicist know anything of the relative size of atoms and their vibratory motions?" The answer is: by mathematical deductions, based upon the behavior of gases; by experimental evidence, principally in the domain of radiant heat; also in the interdiffusion of liquids and gases. Researches