Page:Popular Science Monthly Volume 80.djvu/421



T is my purpose herein to review the history of two of our most fundamental physical theories and to present some very simple and easily intelligible experiments which demonstrate the correctness of these theories, though they are by no means the only experiments which lead to the same goal.

If this statement seems too dogmatic and positive to be scientific let me say that I make it advisedly, for I wish vigorously to combat the point of view which I fear too many of those who are not engaged at first hand in scientific inquiry gain, both from the "revolutionary discoveries" which are continually being announced by the daily press, and also from the prominence which scientists themselves naturally give to the demolition of time-honored hypotheses in which they do not believe—the point of view that none of the theories of the scientists are after all any more than transient phenomena, that they are all just a part of the continual change and flux of things, that this generation discards wholesale all the hypotheses which were held adequate in the last and that the next generation will make equally short work of all the theories which hold sway to-day. In opposition to that point of view I wish to assert that there are some things, even in science, which we may safely say that we know, that there are some theories which we may be reasonably certain are going to endure—that in fact we may divide the theories of science into three categories, with broad and indefinite lines of division between them, it is true, but yet with real dividing areas, if not dividing lines.

In the first category may be placed the theories which we may say that we know are correct, using the word "know" not in the abstract