NATURAL PHILOSOPHY. 



ON THE INTERACTION OF NATURAL FORCES. 



The following lecture by Mr. Helmholtz, Professor of Physiology in the 

 university of Bonn, Germany, translated by Professor Tyndall, and pub- 

 lished in the London Philosophical Magazine, is an exceedingly interesting 

 contribution to science, and, although of considerable length, will well re- 

 pay perusal : 



Anew conquest of very general interest has been recently made by natural 

 philosophy. In the following pages, I will endeavor to give a notion of the 

 nature of this conquest. It has reference to a new and universal natural 

 law, which rules the action of natural forces in their mutual relations towards 

 each other, and is as influential on our theoretic views of natural processes as 

 it is important in their technical applications. 



Among the practical arts which owe their progress to the development of 

 the natural sciences, from the conclusion of the middle ages downwards, 

 practical mechanics, aided by the mathematical science which bears the 

 same name, was one of the most prominent. The character of the art was, 

 at the time referred to, naturally very different from its present one. Sur- 

 prised and stimulated by its own success, it thought no problem beyond its 

 power, and immediately attacked some of the most difficult and complicated. 

 Thus it was attempted to build automaton figures which should perform the 

 functions of men and animals. The wonder of the last century was Vau- 

 canson's duck, which fed and digested its food; the flute-player of the same 

 artist, which moved all its fingers correctly ; the writing boy of the older, 

 and the piano-forte player of the younger Droz : which latter, when perform- 

 ing, followed its hands with his eyes, and at the conclusion of the piece 

 bowed courteously to the audience. That men like those mentioned, whose 

 talent might bear comparison with the most inventive heads of the present 

 age, should spend so much time in the construction of these figures, which 

 we at present regard as the merest trifles, would be incomprehensible, if 

 they had not hoped in solemn earnest to solve a great problem. The writ- 

 ing boy of the elder Droz was publicly exhibited in Germany some years 

 ago. Its wheel-work is so complicated, that no ordinary head would be suf- 

 ficient to decipher its manner of action. When, however, we are informed 

 that this boy and its constructor, being suspected of the black art, lay for a 



