THE FIRST ELECTRICAL MACHINE. 395 



Von Guericke's position is that if the earth is by sub- 

 stance a magnet, it must have all the magnetic proper- 

 ties not only directive virtue or verticity, but also the 

 attractive magnetic power. But in comparing what he 

 calls the conservative virtue of the earth with its directive 

 virtue, he points out that "the former attracts all bodies 

 not only in the regions of the poles but everywhere. The 

 bodies attracted are not .changed but are held by a conser- 

 vative force." 



In other words, von Guericke believes that the magnetic 

 quality of the earth simply adjusts and holds its axis in 

 space and exerts no attractive force on exterior bodies. 

 The attractive force which the earth does manifest is grav- 

 ity, and that is owing to the "conservative virtue." And 

 the "conservative virtue" is the same thing as electrical 

 attraction, which he says is exerted not like magnetic at- 

 traction merely at the poles but at all points of the electric. 

 So, according to him, gravity is not correlated to the 

 earth's magnetism, but is simply the electrical attraction 

 exerted by the earth upon exterior objects, and he believes 

 it to be due to the rubbing of the globe by the sun's rays. 



Note the difference between this conception and Gil- 

 bert's dictum that the "matter of the earth's globe is 

 brought together and held together electrically." Von 

 Guericke's idea is that the earth, as a mass, electrically 

 attracts, not only its own matter, but also outside matter. 



Now what Monconys saw was the experiment which 

 illustrated the possession by the earth of conservative vir- 

 tue that is, electrical attraction and also of the capacity 

 of not only attracting, but repelling other bodies. Von 

 Guericke had copied Gilbert's idea of the earth-kin the 

 terrella but had made his miniature globe, not of a mag- 

 net, but of an electric. And Monconys saw von Guericke 

 rotate that electric globe to imitate the rotating earth, 

 meanwhile rubbing it; and then he also saw, and describes 

 fairly well, the extraordinary phenomena revealed by this 

 first of all electrical machines. 



