256 Mr Charles Tomlinson on Lightning Figures. 
be on the glass, and the action of the electricity seems to be 
to burn off greater or less portions of this film, coinciding with 
the greater or less projections of the coin, so that when the 
breath is projected on the glass, the moisture becomes. con- 
densed in a regulated manner according to the regulated 
action of the electricity on the film; that is, where the elec- 
tricity has touched the glass and burnt off the organic film, 
the breath becomes condensed in continuous streams of water, 
but where the film still remains, the moisture is condensed in 
minute globules. Now, if we discharge a Leyden jar upon a 
pane of glass, by interposing it between the knob of the jar 
and that of the discharging rod, we get a breath figure which 
may be taken as the portrait of the discharge of a miniature 
flash of lightning, representing, doubtless on a small scale, the 
mode of discharge on the large, where the earth and the clouds 
take the place of the two coatings, and the air that of the insu- 
lating glass. In this expermment, a small Leyden jar and a pane 
of window glass three or four inches square suffice. The glass 
should be held by one corner ; and one knob of the discharging 
rod being placed on the coating of the jar, the glass in contact 
with the other knob should be brought quickly up to the knob 
of the jar, when the discharge will take place not through the 
glass but along its surface, turning over its edge, and passing 
up the glass to the knob of the discharging rod on the other 
‘side. Thus we get two figures, the principal one on the side 
next the jar, and a second subsidiary figure on the discharging- 
rod side. These figures come out beautifully by breathing on 
the glass and holding it up to the light. Wherever the elec- 
tricity has burnt off the film, the moisture is deposited in un- 
broken lines; but in the other parts where the film is intact, 
it is in very minute globules. The following engraving 
represents roughly a specimen of the principal figure, 
which is that of a leafless tree, or something so provokingly 
like a tree, that any one who has seen it, and has read 
the wonderful stories from M. Poey’s Memoir, exclaims 
at once— Here is the origin of the photo-electric figures 
of lightning.” I showed this experiment to one of the 
Professors of King’s College, and he exclaimed—* There 
is the branch and there is the bird’s nest as plainly as pos- 
sible!” We have, in fact. in all these figures a broad and 
