took possession of it as a laboratory for the municipal course of
lectures, the nave remained as it was at the time of my former short and
disastrous visit. To the right, on the wall, a number of black stains
struck the eye. It was as though a madman's hand, armed with the inkpot,
had smashed its fragile projectile at that spot. I recognized the stains
at once. They were the marks of the corrosive which the retort had
splashed at our heads. Since those days of long ago, no one had thought
fit to hide them under a coat of whitewash. So much the better: they
will serve me as excellent counselors. Always before my eyes, at every
lesson, they will speak to me incessantly of prudence.

For all its attractions, however, chemistry did not make me forget a
long cherished plan well suited to my tastes, that of teaching natural
history at a university. Now, one day, at the grammar school, I had a
visit from a chief inspector which was not of an encouraging nature. My
colleagues used to call him the Crocodile. Perhaps he had given them a
rough time in the course of his inspections. For all his boorish ways,
he was an excellent man at heart. I owe him for a piece of advice which
greatly influenced my future studies.

That day, he suddenly appeared, alone, in the schoolroom, where I was
taking a class in geometrical drawing. I must explain that, at this
time, to eke out my ridiculous salary and, at all costs, to provide a
living for myself and my large family, I was a mighty pluralist, both
inside the college and out. At the college in particular, after two
hours of physics, chemistry or natural history, came, without respite,
another two hours' lesson, in which I taught the boys how to make a
projection in descriptive geometry, how to draw a geodetic plane, a
curve of any kind whose law of generation is known to us. This was
called graphics.

The sudden irruption of the dread personage causes me no great flurry.
Twelve o'clock strikes, the pupils go out and we are left alone. I know
him to be a geometrician. The transcendental curve, perfectly drawn, may
work upon his gentler mood. I happen to have in my portfolio the
very thing to please him. Fortune serves me well in this special
circumstance. Among my boys, there is one who, though a regular dunce at
everything else, is a first rate hand with the square, the compass and
the drawing pen: a deft-fingered numskull, in short.

With the aid of a system of tangents of which I first