The data of physical science are readily accessible in several published tables Of physical constants. The mathe maties used in physical science has been summarized, classi fied and formulated, for ready reference, in many published books. The author is not aware, however, of any hand-book or reference work which contains a full list of the general propositions or laws of science. Such reference lists are not without value, and this book has been prepared to fill an obvious gap in the literature of Physical Science. Furthermore, it appears to the author that students in any of the branches of Natural Science will not only find guidance, but will also derive inspiration by having before them under a single [view the very epitome of the world's heritage of the fundamentals of its knowledge and wisdom.' None will question that the fundamentals of science are its laws, principles, theorems and precise state ments of the general properties of matter; but it is not always easy for students in one branch of science to find and to know the literature on important principles and facts in an entirely different, or even' in closely allied branches of science. The author hopes that what has been here gath ered together and classified will help such students in their search and give them the means to broaden their view. We have chosen for a title, Laws of Physical Science but many general propositions, theorems and mere state ments of important facts have been included which perhaps.