1873 •] Notices of Books. 395 



that tends to subvert a system of honourable economy, all the 

 reckless venture too often witnessed as the cause of monetary 

 panic. Dr. Yeats's works would be an admirable adjunct to a 

 chair of Commercial Economy ; and it is not Utopian to ex- 

 press the hope that at no far distant date colleges will prepare 

 universally for science, commerce, and the arts. 



Popular Lectures on Scientific Subjects. By H. Helmholtz, Pro- 

 fessorof Physics in the University of Berlin. Translated by E. 

 Atkinson, Ph.D., F.C.S. London : Longmans and Co. 1873. 

 Professor Helmholtz has been known for a number of years 

 in the English scientific world as one of the foremost thinkers 

 of the age, and his admirable Memoirs have from time to time 

 appeared in the " Transactions of the Royal Society," and the 

 " Philosophical Magazine." This is, however, the first time 

 that any of his lectures have been brought within the grasp of 

 the well-informed non-scientific reader. But the book will also 

 be very acceptable to the purely scientific man, for it contains 

 several lectures not before published. Nothing, perhaps, strikes 

 us more in connection with our author than his varied and exact 

 knowledge ; as a pure physicist he takes a very high standing; 

 he has done much to develop the now dominant doctrine of the 

 Conservation of Energy ; he has worked considerably in the 

 domain of thermo-dynamics ; and his acoustic researches are 

 most remarkable and original. Again, he is a good physiologist 

 — indeed he was a military physician in the Prussian service, 

 before he was professor of physiology in the University of 

 Konigsberg, and he held a similar professorship in Heidelberg 

 before he was appointed to his present professorship of physics 

 in Berlin. Wherever points of contact have appeared between 

 pure physical actions and purely physiological actions, he has 

 endeavoured to trace the exact nature and course of the con- 

 current phenomena. His researches on the organs of sight and 

 hearing are of high merit, and receive the admiration alike of the 

 physicist and the physiologist. Add to all this the fact that Prof. 

 Helmholtz is a mathematician ; and, most rare of all, that he 

 can clothe his profound generalisations, in whatever subject he 

 may discuss, in most lucid and elegant diction, and the reader has 

 foreshadowed before him what an intellectual feast he may ex- 

 pect from the work we are about to examine. 



The lectures have been delivered at various times during six- 

 teen years; one, "On Goethe's Scientific Researches," so long 

 ago as the spring of 1853 ; another, " On the Interaction of the 

 Natural Forces," in 1854; and the latest, "On the Aim and 

 Progress of Physical Science," in 1869. As to the purport of 

 the lectures, the author says : — " If I may claim that they have 

 any leading thought, it would be that I have endeavoured to 

 illustrate the essence and import of natural laws, and their re- 

 lation to the mental activity of man. This seems to me the chief 



