130 Transactions of the South African Philosoj^hical Society. 



order, so that the mean time for the positive pair was approximately 

 the same as for the negative pair. The charging was done from the 

 town hghting mains, and was generally at a potential of + 210-230 

 volts. 



The insulation of the instrument, with the distributor removed, 

 was found to be to all intents and purposes perfect. 



The series of observations was commenced on May 21st, and has 

 been continued up to the present (August 25, 1902). The readings 

 of the barometer, wet and dry bulb thermometers, and the state of 

 the weather were noted at about the mean time of each set of 

 observations. 



During the interval between May 21st and May 30th inclusive,, 

 the mean positive and negative leaks in the morning were 3*0 and 2-8 

 scale divisions respectively, and in the afternoon 3-7 and 3*8 scale 

 divisions, showing no remarkable differences between the rates of 

 leak of positive and negative electricities, but a decided increase in 

 the afternoon over the leak in the morning. 



The results for the month of June bear this out, showing average 

 leaks of 2-65 divisions in the morning and 3*5 divisions in the 

 afternoon for both positive and negative electricity. 



The figures for July were 3*02 and 3*33 for positive and negative 

 respectively in the morning, and 4'66 and 4*57 in the afternoon. 



The readings for June have been more fully analysed than the 

 rest, having been converted into volts and the fall in each case 

 divided by the mean P.D. between the leaves and the case, for the 

 time during which the fall took place. 



The results so obtained are plotted side by side in a diagram, with 

 the corresponding barometer readings. No close connection is 

 noticeable between the atmospheric pressure and the rate of leak, 

 nor was the relation between the relative humidity of the atmosphere 

 and the rate of leak found to be any more marked. 



The results of the months of May, June, July may then be 

 summarised as follows : — 



Month. Mean pos. leak in scale div. Mean neg. leak in scale div. 

 Morning. Afternoon. Morning. Afternoon. 



May 3-0 3-7 2-8 3-8 



June 2-65 3-5 2-65 3-5 



July 3-02 4-66 3-33 4-57 



