446 Dr. G. Gore on the Influence of Proximity 



usual each following morning, the " A " electrodes having 

 been under the influence of the lead with the circuit open all 

 night, and 115 observations were taken during 8 mornings. 



The average amount of deflexion obtained with the "A" 

 electrodes was 32*4 and with the " B " ones —2*9. The 

 usual period after the circuit was closed in which the amount 

 of effect attained its maximum was in these cases also nearly 

 two hours. The results agreed with the previous ones and 

 with the further conclusion that the influence of the lead 

 upon the electromotive force was increased by time up to a 

 certain limit. 



3rd Series. — Influence of Period of Reversal. 



The hour of the day at which the reversals were made in- 

 stead of being later was now changed to 9 a.m. after the 

 circuit including the galvanometer had been closed all night, 

 the bars of lead being still used and all the other conditions 

 remaining the same. — Ninety-seven observations were made 

 during 5J days. The average amount of deflexion with the 

 " A " electrodes during 2 J days was 31'0, and with the " B " 

 ones during three days 1*4. These results confirmed the 

 previous ones and showed that altering the period of reversing 

 the electrodes had no conspicuous effect. The usual period 

 after each reversal in which the effect of the lead attained its 

 maximum was about two hours. In one instance the influence 

 of proximity of the lead was sufficient to reverse the direction 

 of the deflexion. The results showed that the differences of 

 effect attending the presence and absence of the lead were 

 not due to diurnal changes of magnetism. 



Influence of Conduction- resistance. 



In order to ascertain the influence of extra total resistance 

 upon the time required for the lead to produce its full effect ; 

 whilst the " A " electrodes were between the bars of lead and 

 the full effect had been attained, an extra resistance of about 

 6000 ohms was suddenly inserted in the circuit, and the effect 

 allowed to develop. At the end of 3J hours the influence of 

 the lead was still increasing and had not arrived at its usual 

 maximum. 



After allowing the circuit to remain closed all night the 

 maximum effect of the lead appeared to be about the same as 

 when the 6000 ohms were not in the circuit. The " B 9 * 

 electrodes were now substituted for the " A " ones and the 

 apparatus allowed to remain undisturbed. The maximum 

 effect was now attained in a period of about 3-J- hours. 



These results, when compared with previous ones, indicated 



