Show me a man who makes no mistakes, and I will show you a man who has done nothing.Liebig. In this little volume the author gives but his own personal opinions upon the subjects discussed, and although the sentiments are expressed with an assurance born of conviction, yet he claims not infallibility. He has ever been unable to accept the usual explanations of the great physical forces; and the inadequacies of mooted theories have impelled him to efforts for more philosophical interpretations. If in his investigations he has been forced to strange and unusual conclusions, he has been actuated only by an honest desire to promote the advancement of science. He is not insensible to the responsibility of the position which he thus voluntarily assumes, in asserting his opinions upon problems so vast and momentous