446 



T. Mizuno on the Action of the Coherer. 



which led to the arms of a Wheatstone's bridge. The gal- 

 vanometer used was a Kelvin's astatic double-coil one. The 

 bridge-current was supplied by a single Daniell cell, the 

 resistance, ranging between 1000 and 2000 ohms, being 

 always inserted in the circuit before the current eutered the 

 arms of the bridge. This precaution was. as I found, es- 

 pecially requisite, because when the current exceeded a 

 certain strength, the resistance of the coherer often underwent 

 very marked spontaneous fluctuations during the repeated 

 processes for balancing the bridge. This phenomenon was 

 perhaps due to the self-induction effectof the galvanometer-coil. 

 Taking the above precaution, I have made a general 

 survey of metals, some alloys, and iheir mixtures. So far as 

 I am aware, all the investigators of the coherer simply 

 measured the change of its resistance under the action of a 

 given electric radiation, but did not, any of them, go so far 

 as to examine the successive states of affairs under repeated 

 radiations. My method of procedure was entirely different, 

 and I studied the history, so to speak, of the successive 

 changes of the resistance of the coherer accompanying suc- 

 cessive oscillating sparks of the Hertzian vibrator. The 

 results obtained with the several metals, alloys, and their 

 mixtures respectively are tabulated and also plotted in the 

 following tables and diagrams : — 



Table 1. 



Number of 

 Sparks. 



, 



1 , 

 2 

 3 

 4 

 5 

 6 

 7 

 8 

 9 



10 

 11 

 12 

 13 

 14 

 15 

 16 

 17 

 18 

 19 

 20 

 25 



Brass. 



262-0 

 1460 

 86-0 

 91-2 

 80'0 

 79-3 

 78-9 



74-1 

 834 



77-4 



79-3 



82-0 

 80-3 

 79-9 



84-0 



German 

 Silver. 



oo 

 150 

 132 

 149 

 114 

 110 

 97 

 96 



97 

 99 



102 

 99 



101 



Electric 

 Fuse. 



87-0 

 oo 

 121-0 

 590 

 56-3 

 55-2 



546 

 53-0 



52-9 



52-7 



Soldering 

 Fuse. 



104 





103 



53-3 



100 



52-5 



102 



52-2 



100 



51-4 



99 



oo 



45-4 

 44-3 

 47-3 

 78-0 

 340 

 337 



33-9 



37-0 



Rose's 



Wood's 



Metal. 



Metal. 



oo 



oo 



122-0 



430 



66-0 



520 



61-7 



460 



;) 



42-0 



670 





650 



41-7 



64-4 



41-5 



67-0 





60-0 



» 



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