he law that, whatever quantity of oil
might be in the lamp, the position of equilibrium just brought the oil up
to the edge of the cylinder, at which a bit of wick was placed. As the wick
exhausted the oil, the cylinder slowly revolved about the pivots so as to
keep the oil always touching the wick.

Great discoveries are always laughed at; but it is very often not the laugh
of incredulity; it is a mode of distorting the sense of inferiority into a
sense of superiority, or a mimicry of superiority interposed between the
laugher and his feeling of inferiority. Two persons in conversation {253}
agreed that it was often a nuisance not to be able to lay hands on a bit of
paper to mark the place in a book, every bit of paper on the table was sure
to contain something not to be spared. I very quietly said that I always
had a stock of bookmarkers ready cut, with a proper place for them: my
readers owe many of my anecdotes to this absurd practice. My two
colloquials burst into a fit of laughter; about what? Incredulity was out
of the question; and there could be nothing foolish in my taking measures
to avoid what they knew was an inconvenience. I was in this matter
obviously their superior, and so they laughed at me. Much more candid was
the Royal Duke of the last century, who was noted for slow ideas. "The rain
comes into my mouth," said he, while riding. "Had not your Royal Highness
better shut your mouth?" said the equerry. The Prince did so, and ought, by
rule, to have laughed heartily at his adviser; instead of this, he said
quietly, "It doesn't come in now."

HERBART'S MATHEMATICAL PSYCHOLOGY.

De Attentionis mensura causisque primariis. By J. F. Herbart.[578]
Koenigsberg, 1822, 4to.

{254}

This celebrated philosopher maintained that mathematics ought to be applied
to psychology, in a separate tract, published also in 1822: the one above
seems, therefore, to be his challenge on the subject. It is on _attention_,
and I think it will hardly support Herbart's thesis. As a specimen of his
formula, let _t_ be the time elapsed since the consideration began, [beta]
the whole perceptive intensity of the individual, [phi] the whole of his
mental force, and _z_ the force given to a notion by attention during the
time _t_. Then,

z = [phi] (1 - [epsilon]^{-[beta]t})

Now for a test. There is a _jactura_, _v_, the meaning of which I do not
comprehend. If there be anything in it, my mathematical readers ought to
i