376 ; Analyses of Books.’ - ~~ [Novw. 
with magnetism, have opened an extensive field of inquiry in 
physical science, and have imparted much additional interest to 
electrical investigations. 
“Is electricity a subtile elastic fluid? Or are electrical effects 
merely the exhibition of the attractive powers of the particles of 
bodies ? Are heat and light elements of electricity, or merely the 
effects of its action? Is magnetism identical with electricity, or 
an independent agent put in motion or activity by electricity?” 
The solution of these queries, it is observed, “is of the high- 
est importance, and though some persons have undertaken to 
answer them in the most positive manner,” yet there are few 
sagacious reasoners who think that our present data are suffi- 
cient for decision in such abstruse parts of corpuscular philo- 
sophy. 
“It appeared to me,” continues Sir Humphry, “ an object of 
considerable moment, and one intimately connected with all 
these queries, the relations of electricity to space, as nearly void of 
matter as it can be made on the surface of the earth.’ Walsh and 
Morgan had concluded from their experiments, that the electrical 
