30 Electric and Magnetic Science 



orientations ; while the electric force merely tends to heap them 

 together in shapeless clusters. 



These facts appeared to Gilbert to indicate that electric 

 phenomena are due to something of a material nature, which 

 under the influence of friction is liberated from the glass or 

 amber in which under ordinary circumstances it is imprisoned. 

 In support of this view he adduced evidence from other quarters. 

 Being a physician, he was well acquainted with the doctrine 

 that the human body contains various humours or kinds of 

 moisture phlegm, blood, choler, and melancholy, which, as 

 they predominated, were supposed to determine the temper of 

 mind; and when he observed that electrifiable bodies were 

 almost all hard and transparent, and therefore (according to the 

 ideas of that time) formed by the consolidation of watery liquids, 

 he concluded that the common menstruum of these liquids must 

 be a particular kind of humour, to the possession of which the 

 electrical properties of bodies were to be referred. Friction 

 might be supposed to warm or otherwise excite or liberate the 

 humour, which would then issue from the body as an effluvium 

 and form an atmosphere around it. The effluvium must, he 

 remarked, be very attenuated, for its emission cannot be detected 

 by the senses. 



The existence of an atmosphere of effluvia round every 

 electrified body might indeed have been inferred, according to 

 Gilbert's ideas, from the single fact of electric attraction. For 

 he believed that matter cannot act where it is not ; and hence 

 if a body acts on all surrounding objects without appearing to 

 touch them, something must have proceeded out of it unseen. 



The whole phenomenon appeared to him to be analogous to 

 the attraction which is exercised by the earth on falling bodies. 

 For in the latter case he conceived of the atmospheric air as the 

 effluvium by which the earth draws all things downwards to 

 itself. 



Gilbert's theory of electrical emanations commended itself 

 generally to such of the natural philosophers of the seventeenth 

 century as were interested in the subject ; among whom were 



