EXCURSIONS OF THE CAPILLARY ELECTROMETER. 
105 
although it has many advantages, can only give the average time-relations of a 
number of electrical variations due to a rapid succession of stimuli, and is inapplicable 
in any case in which changes may occur in the preparation from fatigue. Moreover, 
my experience of rheotomes leads me to believe that it is much more difficult than is 
sometimes supposed to obtain very short closures of constant duration. The photo¬ 
graphic records given by the capillary electrometer are free from both these objections. 
They show the result of a single stimulus or of a number in rapid succession, and the 
circuit remains unbroken and therefore constant. 
Hitherto no means by which these indications could be quantitatively interpreted, 
except in the case of slow changes, has been in the hands of experimenters. I have 
endeavoured to supply this lack, and in doing so, to represent the capillary electro¬ 
meter in its true light as a measuring instrument, not indeed equal to the galvano¬ 
meter in delicacy, nor in durability, nor, perhaps, in accuracy ; but far excelling it 
and all other electrical measuring instruments in the one property which is peculiar 
to it, namely, rapidity of action. 
Probably in this way the electrometer may be made to serve other purposes than 
those of physiological research ; and I foresee that this method of analysis may be 
applicable to other instruments than the electrometer. 
All the photographs and many of the experiments described in this paper were 
made in the Physiological Laboratory, Oxford, and my thanks are due to Professor 
Bukdon Sanderson for his help and counsel, without which I could not have com¬ 
pleted the research. I have also to thank Mr. C. Crump, of the Record Office, for 
his valuable assistance in discussing the mathematical parts of the problem. The 
complete method of applying the corrections for calibration error and change of 
resistance I had hoped to give with his aid, but it was found that some further 
experiments would be necessary to furnish the requisite data. The treatment of this 
part of the subject therefore must be deferred. In the instrument which was used 
for nearly all the photographs these errors were not sensible. 
[Note.— The curves were analysed by measuring the negatives, and the results 
plotted from left to right. The photographs having been reproduced as prints, must 
be read in the reverse direction, from right to left. March 3, 1892. G. J. B.] 
MDCCCXCII.—A. 
JP 
