174 On the Excursions of the Capillary Electrometer. [Nov. 19, 



from the asymptotic circle, and consequently, by the same reasoning 

 on which the previous method of analysis was based, represents, on a 

 scale which can be easily determined, and which is constant so long 

 as the resistance in circuit is unchanged, the difference of potential 

 between the terminals of the electrometer, minus or plus the 

 difference of potential indicated by the position of the meniscus above 

 or below the zero-line. 



Analysis of a Normal Curve. 



Full details are given of the measurement of a normal curve, the 

 equation to which was shown to be y = ae~ c9 , the maximum differ- 

 ence between the observed and the calculated values being only 

 0'071 mm. The constant multiplier in this case was c 8'50. 

 Details of five other smaller excursions of known value are also given, 

 showing that the error in determining differences of potential by this 

 method is less than 1 per cent. 



Artificial Spikes. 



This name was given to excursions produced by two currents in 

 opposite directions, each lasting about O005 second. It was intended 

 by this means to investigate the effects of overshooting, and also to 

 ascertain whether the electrometer was capable of discriminating 

 between a current of definite strength suddenly communicated to it, 

 and a more or less gradual rise of a difference of potential extending 

 over a period of equal duration. That it can do so was clearly estab- 

 lished. The effect of the elasticity of the meniscus, and of overshoot- 

 ing proper, is shown. With no resistance in circuit it did not exceed 

 O'Ol of the full excursion, and was rendered inappreciable by the 

 introduction of a few thousand ohms. 



PART II. 



Application of the Method to the Study of the Electrical Variations of 



Muscle. 



After a brief sketch of the problem under consideration and the 

 mode in which the physiological experiments were made, the author 

 describes minutely the manner in which a muscle-curve is analysed. 

 In order to illustrate the kind of information which can be thus ob- 

 tained, he gives a series of specimen records of the electrical variations 

 of the gastrocnemius of the frog, together with the analysis of each. 

 T^he interpretation of the results, from a physiological standpoint, he 

 desires to leave entirely in the hands of Professor Burdon Sanderson, 

 to whom he is indebted for permission to make use of the photo- 

 graphs. 



