an Induction-Coil by the Ard of Ausiliary Wires. 491 
The term “assister detached ” means X’ nearly in contact 
with L (the gap varied usually from $ to 1 mm.). 
To start with, it was found that an assister arranged in 
this way gave almost as great an effect as an assister arranged 
to have approximate contact with K, and of course it was 
more convenient to experiment with. 
It was found that a sheet of mica placed midway between 
the assister terminal and the spark-gap caused hardly any 
diminution of the lengthening effect of the assister. A plate 
_ of vuleanite 3 mm. thick acted in the same way as the mica. 
The effect, therefore, in this case could not be due to 
ionization produced by electrons proceeding from the nega- 
tive.assister. 
Experiments were tried to find how the effect of the negative 
assister varied when placed at different distances from the 
positive terminal. With assister of wire 1 mm. in diameter 
and 100 mm. long, the following results were obtained. 
(The assister XX’ was on a line from A at right angles to 
the spark-vap AK.) 
Spark-gap. 
LOMMRISSTEGE GL OTs en 45 mm. 
XA= 63 mm. and XX’ detached ........ 3 
XA= 90 “re «oie (ok, Nim eae ae a5 
XA=120 oc | lla Sg Sass eg aa 50 
Hixperiments were tried to show the effect of moving XX’ 
parallel to itself towards A. 
Keeping the distance from X to AA’=65 mm. and XX’ 
being detached—the following results were obtained :— 
Spark-gap. 
[ITS SECIS UR Ip” oie, A AO al 45 mm. 
eto AA’ — Go mm. A> to lime of XX =O... cots 67 
- A ss XX AO) mines 65 
a A ns X= 30 Res 58 
5 A X'X=120 NE 54. 
‘aid A fe X'X=160 Bey, AT 
Experiments were then tried to show the effect of the 
assister when “‘detached” and when “attached.” When 
trying these, it was observed that when the vulcanite screen 
was brought very close to the point of the assister, then a 
decided diminution of the lengthening effect of the assister 
was produced when the assister was in the “detached” position. 
With negative assister at distance XA=50 mm., the 
vulcanite screen midway between X and A :— 
Spark-gap. 
UMASSIStEG: ene oe yc ats ecu d 75 mm. 
Wath. assister ahtteledie.. ohn eae dle s dare es 83 
With assistertdetaemeds 2 ess ber ek a Tih 
Showing that in this case (with the unassisted spark-gap 
