54 STUDIES IN ELECTRO-PHYSIOLOGY: 



static capacity is also known, because when perfectly 

 insulated the body can be charged to a high potential. 

 That it has inductive capacity also is not so well under- 

 stood. 



So far as capacity is concerned, we may liken the body 

 to a collection of storage cells or Leyden jars, which are 

 liable to become more or less highly charged, or to have their 

 charge altered by any direct or passing current or exciting 

 influence, or change in exterior insulation. 



Now, these storage cells or Leyden jars cannot, if they 

 depend for their charge upon some outside source of 

 energy as the exciting influence, be in a constant state of 

 tension, because the outside current is not always flowing 

 either to charge them directly or by passing in their 

 vicinity. We must then depend upon muscular move- 

 ment for the charge, and if we find, as we do find, that 

 movement of any kind exercises only a momentary effect 

 upon the human electromotive force, and that, within 

 limits, such electromotive force continues to be produced 

 even when the body is absolutely motionless, we must look 

 further for the source of energy. 



CAUSES WHICH HAVE CONTRIBUTED TO ERROR. 



We will now take the three factors I have mentioned 

 seriatim, but before doing so it would be well to mention 

 that in the majority of tests, upon which the conclusions 

 to be given hereafter are based, a Kelvin Astatic reflecting 

 galvanometer of a resistance of 88,000 B.O.T. ohms at 

 15 C. and perfect insulation was used. This instrument 

 was made for me by Elliott Bros., of Lewisham, and its 

 sensibility was such that a scale deflection of 400 mm. 

 from a central zero could be obtained with a current of 

 0-1 micro-ampere. (See p. 235.) 



The electrodes I will describe later. 



