1891.] 



the Disc/targe of Ley den Jars. 



9 





cascade of sparks ; the number of these splashes gradually decreasing 

 down to one again as the spark A was shortened. 



It was also found that after an overflow another was more likely,, 

 whereas after a failure another failure was probable : that there was y 

 in fact, a kind of hysteresis, the conditions of overflow being easier 

 for a decreasing A spark than for an increasing one of the same 

 length. This seemed especially noticeable when the long connector 

 was thin copper, instead of being so thick and massive as the No. 1 

 copper on the one hand, or so highly resisting as thin iron on the other. 



The table on p. 10 summarises the readings. The full contrast 

 does not come out strong in the early numbers : there is some caprice 

 about whether the jar overflows or not, probably having something 

 to do with the state of the glass surface. 



The contrast comes out best towards the middle of the table. The 

 " thick copper" and other long wires are those specified in 2. 



Spiral Conductor. 



6. Another connecting path was now made, consisting of 8 yards 

 of the No. 1 copper wound into an open spiral about a foot in 

 diameter, and suspended in air by ribbon, as indicated by the dotted 

 line in fig. 5 ; when in use, its two ends were led, one to a machine 

 terminal, the other to outer coat of gallon jar, whose inner coat was 

 connected to the other machine terminal. 



This being so, the lengths of machine spark needed to make the 

 jar overflow (round its lip always) under different circumstances were 

 again read as follows : 



Kind of connector used. 



Length of a spark needed 

 for overflow. 



fThick copper spiral 

 Short circuit . . . 



'" | Spiral again 



J3 -\ Long thick wire round room 

 ^ Both this and spiral in series 



<5 I The two in parallel 



^The spiral alone again 



f Thick copper spiral 



Thick wire round room 



Spiral 



Short circuit 



Spiral 



( Thick iron wire round room 



Iron and copper round room in parallel. 



Iron alone 



Copper alone 



Short circuit 



^Copper again 



-61 inch. 



1 -50 

 '(53 

 0-57 

 0-56 

 062 

 -61 



-58 to -52 inch. 

 0'51 inch. 

 0-53 



0-54 



-66 



0-62 



0-67 



0-52 



1-4 



0-52 



