ON THE PRESENT FUNDAMENTAL CONCEPTIONS OF PHYSICS. 



(TWO LECTURES DELIVERED IN VIENNA ON THE IOtii AND 17th OF 



DECEMBER, 1879.) 



By Prof. Dr. Franz Joseph Pisko. 



[Translated from the German by L. Stoerzer.] 



Lecture I. 



He who compares the fundamental principles of physics accepted 

 at present with those prevalent several decades ago must necessarily 

 be astonished at the changes which have occurred within the domain of 

 these branches of science. The " Imponderables" have fallen to the 

 ground and have made way for the various motions and forms of motion 

 of a hypothetical universal aether and the ultimate atoms of matter. 

 One single natural force, or rather one single original universal motion 

 is recognized, which manifests itself in various forms, such as cohesion, 

 adhesion, chemical affinity, gravitation, heat, light, electricity, and mag- 

 netism.* This changed fundamental principle lends to modern physics 

 a coherent and attractive form, which essentially distinguishes it from 

 the incomplete and unsatisfactory system of the older physics. The new 

 system has a very simple basis, and the modern structure of natural 

 philosophy appears accordingly much more connected, comprehensive, 

 and translucent than the old defective and disjointed edifice. 



The physics of to-day is shaped into a logically-constructed theory of 

 motion or kinematics (dynamics). It is however not merely the outward 

 form of the science which is altered, but the comprehension of natural 

 phenomena and laws has also undergone a far-reaching and radical 

 change. For instance, if formerly the falling of a stone was observed, 

 it was believed that on the stone's reaching the ground all its motion 

 had ceased ; it was, according to this, considered possible that motion 



* [The hypothesis advanced by many popular expounders of science, that all the 

 forces and properties of matter are to be ultimately resolved into molecular or atomic 

 motion, is a remarkable instance of premature and over generalization. In the Smith- 

 sonian Report for 187G (pages 275-27'J) reasons were given for believing that gravitation 

 cannot be resolved into any form of motion; and further, that without an inscrutable 

 "force" underlying all motion and antecedent to it, no rational conception of dynamics 

 is possible. Without the ultimate (irresolvable) fact of "elasticity" in material ele- 

 ments (for example), neither transformation of motion nor conservation of energy could 



have auy conceivable basis. — Ed.~\ 



485 



