UISC'OVERIES IN THE CELESTIAL SPACES. 343 



Bubsequently led to the establishment 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-produced elec- 

 tricity In an experiment instituted by Newton in 1675, the. 

 first traces of the electric charge in a rubbed plate of glass 

 were seen.* We have here only sought the earliest germs 

 of electric knowledge, which, in its great and singularly-re- 

 tarded development, has not only become one of the most im- 

 portant branches of meteorology, but has also thrcwn much 

 light on the internal action of terrestrial forces, since magnet- 

 ism has been recognized as one of the simplest forms mider 

 which electricity is manifested. 



Although Wall in 1708, Stephen Gray in 1734, and Nob . 

 let conjectured the identity of friction-electricity and of light- 

 ning, it was first proved with empirical certainty in the mid- 

 dle of the eighteenth century by the successful efforts of the 

 celebrated Benjamin Franklin. From this period the electric 

 process passed from the domain of speculative physics into that 

 of cosmical contemplation — from the recesses of the study to 

 the freedom of nature. The doctrine of electricity, like that 

 of optics and of magnetism, experienced long periods of ex- 

 tremely tardy development, until in these three sciences the 

 labors of Franklin and Volta, of Thomas Young and Mains, 

 of Oersted and of Faraday, roused their cotemporaries to an 

 admirable degree of activity. Such are the alternations of 

 slumber and of suddenly-awakened activity that appertain to 

 the progress of human knowledge. 



But if, as we have already shown, the relations of tempera- 

 ture, the alternations in the pressure of the atmosphere, and 

 the quantity of the vapor contained in it, were made the ob- 

 ject of direct investigation by means of the invention of ap- 

 propriate, although still very imperfect physical instruments, 

 and by the acute penetration of Galileo, Torricelli, and the 

 members of the Accademia del Cimento, all that refers to the 

 chemical composition of the atmosphere remained, on the other 

 hand, shrouded in obscurity. The foundations of pneumatic 

 chemistry were, it is true, laid by Johann Baptist von Hel- 

 mont and Jean Key in the first half of the seventeenth cen- 

 tury, and by Hooke, Mayow, Boyle, and the dogmatizing Be- 

 cher in the closing part of the same century ; but, however 

 Btriking may have been the correct apprehension of detached 

 and important phenomena, the insight into their connection 

 WDS still wanting. The old belief in the elementary simplit^- 

 * Brewster, Life of Newton, p. 307. 



