ely lost his memory in consequence of
an acute fever, that he forgot not only the languages he had formerly
learnt, but even the alphabet; and was hence under the necessity of
beginning to read again. His own poems and compositions were shown
to him, but he could not he persuaded that they were his production.
Afterwards, however, he began once more to compose verses; which had so
striking a resemblance to his former writings that he at length became
convinced of his being the author of them.--_From the Doctor._

* * * * *

READING COINS IN THE DARK.

(_From Sir David Brewster's Letters on Natural Magic_.)

Among the numerous experiments with which science astonishes and
sometimes even strikes terror into the ignorant, there is none more
calculated to produce this effect than that of displaying to the eye
in absolute darkness the legend or inscription upon a coin. To do this,
take a silver coin, (I have always used an old one,) and after polishing
the surface as much as possible, make the parts of it which are raised
rough by the action of an acid, the parts not raised, or those which
are to be rendered darkest, retaining their polish. If the coin thus
prepared is placed upon a mass of red hot iron, and removed into a dark
room, the inscription upon it will become less luminous than the rest,
so that it may be distinctly read by the spectator. The mass of red hot
iron should be concealed from the observer's eye, both for the purpose
of rendering the eye fitter for observing the effect, and of removing
all doubt that the inscription is really read in the dark, that is,
without receiving any light, direct or reflected, from any other body.
If, in place of polishing the depressed parts, and roughening its raised
parts, we make the raised parts polished, and roughen the depressed
parts, the inscription will now be less luminous than the depressed
parts, and we shall still be able to read it, from its being as it were
written in black letters on a white ground. The first time I made this
experiment, without being aware of what would be the result, I used a
French shilling of Louis XV. and I was not a little surprised to observe
upon its surface in black letters the inscription BENEDICTUM SIT NOMEN
DEI.

The most surprising form of this experiment is when we use a coin from
which the inscription has been either wholly obliterated, or obliterated
in such a degree as to be illegible. When