I ran forward to put it out, but found that there was no heat in it;
lighting my lamp I could no longer see it, but on the table I found a few
grains of the stuff I had been experimenting on. Turning out the lamp the
light was again visible, and after much thought I concluded that it was
similar to the light given by the little creatures called glowworms, and
which in its turn somewhat resembles the light that can be seen at times
in a pile of decaying fish. I tried many experiments, but as nothing came
of them I gave them up, not seeing that any use could come of a fire that
gave out no heat. I produced a powder, however, that when rubbed on any
substance, became luminous in the dark, presenting an appearance strange
and sufficiently alarming to the ignorant.

"Thinking the matter over some time ago, I took a little of this powder
from the phial in which I had stored it away, and, moistening it, rubbed
it on the wall in the form of circles, triangles, and other signs. I did
this just before it became dark. As the moisture dried, these figures
gradually assumed a luminous appearance. I saw the use to which this could
be put in awing a mob, and, setting to work, made a large supply of this
powder."

"How long does it retain its light, father?"

"That is uncertain. For some hours in a darkened room, the light gradually
growing fainter, but if a bright day follows, the figures stand out on the
following night as brightly as before; while if the day is dull they show
up but faintly at night. I see not that any use can come of such a thing,
for the light is at all times too faint to be used for reading unless the
page is held quite close to it. Come downstairs with me and I will show
you the head of one of the old Roman statues that was dug up near
Rochester, and which I bought for a few pence last year."