TERRESTRIAL MAGNETISM, ETC. 247 



that there is a real physical action of a magnet 

 through all the space round it though no other 

 magnet be there to experience force and show its 

 effects. The meaning of the little bars bordering 

 the terella in Lochman's frontispiece is explained 

 near the beginning of Gilbert's book (Lib. I. Cap. 



FIG. 33- 



iii.), where he describes a very fine iron wire, "of 

 the length of a grain of barley," placed upon a 

 terella and standing erect from the surface at either 

 of two points, which he calls poles, but taking ob- 

 lique positions at other points, and lying flat at any 

 point of a circle midway between the two poles. 



