PROFESSOR IN BERLIN 371 



of this science from any aims of terrestrial utility, the old rule 

 has held good here, that all serious scientific work must 

 eventually find its practical application, even where this might 

 previously have been least expected. Apart from the fact that 

 astronomy has brought about a total revolution in our concep- 

 tion of the world, in consequence of the ideas it has given us of 

 the construction of the Universe, our navigation and the 

 determination of civil and historical chronology depend essen- 

 tially upon it; and the art of practical optics, of the higher 

 branches of clockmaking, and all refinements of longitudinal 

 and angular measurement, have developed directly out of its 

 problems. Lastly, it would be of the utmost importance for 

 higher scientific education if a small and select number of young 

 men who had already proved their capability for experimental 

 work could be admitted as Assistants or Volunteers at such an 

 Institute, and thus have opportunity to learn the application of 

 the most perfect methods and instruments possible.' 



Helmholtz then enters in detail into the reasons why the 

 establishment of a scientific department of the Physico-technical 

 Institute along with that of technical mechanics would be 

 desirable. He had already outlined the duties of the scientific 

 department of the proposed Physico-mechanical Institute as 

 follows : 



' i. The exact determination of the intensity of gravity, and 

 the comparison of this force at different parts of the Earth's 

 surface. 



1 2. The absolute measurement of gravitation, or the determina- 

 tion of the mean density of the Earth. 



' 3. The continuation of the exact determination of the velocity 

 of light at terrestrial distances, with the object of reducing cosmic 

 distances to terrestrial measures of length. 



' 4. In the theory of the magnetic actions of electrical currents 

 a velocity, which appears to be exactly equal to that of light, 

 and which W. Weber characterizes as critical, . . . seems to play 

 a fundamental part. Its identity with the velocity of light 

 appears to me to indicate an essential and intimate relation 

 between optical and electrical processes. We seem hereby to 

 acquire a clue to the mysterious aspects of electromagnetic 

 phenomena, which probably may lead us to their deepest 

 foundation. 



B b 2 



