ig 
0. N. Rood on the discharge of a Leyden jar. 159 
(c) With brass points, this same figure was produced, yet 
een. 
not quite so distinctly. The tail was of course green 
Total duration of the discharge. 
(a) Using brass balls, 
Rate of rotation Number of Distance of elect- Duration in 
per second. observations. rodes in millimeters. seconds. 
109 3 000050 
291° 5 2 000028 
294: 9 1 ‘000017 
120° 6 ac: ‘000030 
30° 8 1 000023 
110: 15 A ‘000022 
No red tail was ever observed in my experiments, the amount 
of electricity employed not being sufficient for its production. 
he difference in these observations arises partly from the faint- 
ness of the terminal portion of the tail, and also from the fact 
that its length is a little variable even in discharges following 
each other in quick succession. Still on the whole, these re- 
sults correspond pretty well with those obtained by Feddersen, 
when it is remembered that the coating of the jar employ: ed by 
me, was less than one half the size of that used by him, which, 
as well as shortening the “striking distance,” tends to lessen 
the duration of the discharge as proved by his observations. 
(6) Using brass points. 
Rate of rota- ‘ tions. Distance of elect- Duration in 
tion per second, He, of Cen eey rodes in millimotess. seconds. 
10 1 000025 
48 10 1 ‘000028 
(c) When platinum points were used as electrodes, with a 
striking distance of three millimeters, the duration, as obtained, 
varied between ‘00004 and 00014 of a second: the variation 
Seems to be owing to the faintness and narrowness of the tail, 
which rendered observation difficult and rather uncertain. 
Duration of the white and yellow portion. 
be rather brownish-yellow, shading off and 
illumination toward its farther boundary. 
