THE UNIVERSE. DISCOVERIES IN THE CELESTIAL SPACES. 341 



Guerike, was the first who observed more than mere pheno- 

 mena of attraction. In his experiments, made with a 

 rubbed cake of sulphur, he recognised phenomena of 

 repulsion, which afterwards led to a knowledge of the laws 

 of the sphere of action and of the distribution of electricity. 

 He heard the first sound and saw the first light in artificially 

 elicited electricity. In an experiment made by Newton in 

 1675, the first traces of the "electric charge" in a rubbed 

 plate of glass were seen. ( 529 ) We have here sought out 

 only the first germs of the science of electricity, which, in 

 its great and singularly retarded development, has not only 

 become one of the most important parts of meteorology, 

 but also, since we have learned that magnetism is one of the 

 manifold forms in which electricity discloses itself, has 

 cleared up to us so much belonging to the internal operation 

 of terrestrial powers or forces. 



Although Wall in 1708, Stephen Gray in 1734, and 

 Nollet, conjectured the identity of friction electricity and of 

 lightning, yet the experimental certainty was first attained 

 about the middle of the 18th century by the successful 

 endeavours of the illustrious Benjamin Franklin. Prom 

 this epoch the electric process passed from the domain of 

 speculative physics to that of the cosmical contemplation of 

 nature from the chamber of the student to the open field. 

 The doctrine of electricity, like that of optics and of mag- 

 netism, has had long periods of exceedingly slow development, 

 until in these three branches the labours of Franklin and 

 Yolta, Thomas Young and Malus, Oersted and Faraday, 

 aroused their cotemporaries to an admirable activity. The 

 progress of human knowledge is generally connected with such 

 alternations of slumber and of suddenly awakened activity. 



