system and more powerful than the terrestrial magnetism by reason of
its comparative nearness, the insect will lose its bearings.
Naturally, in setting down these lines, I take shelter behind the
mighty reputation of the learned begetter of the idea. It would not be
accepted as serious coming from a humble person like myself. Obscurity
cannot afford these audacious theories.

The experiment seems easy; it is not beyond the means at my disposal.
Let us attempt it. I magnetise a very fine needle by rubbing it with
my bar magnet; I retain only the slenderest part, the point, some five
or six millimetres long. (.2 to .23 inch.--Translator's Note.) This
broken piece is a perfect magnet: it attracts and repels another
magnetised needle hanging from a thread. I am a little puzzled as to
the best way to fasten it on the insect's thorax. My assistant of the
moment, the pharmaceutical student, requisitions all the adhesives in
his laboratory. The best is a sort of cerecloth which he prepares
specially with a very fine material. It possesses the advantage that
it can be softened at the bowl of one's pipe when the time comes to
operate out of doors.

I cut out of this cerecloth a small square the size of the Bee's
thorax; and I insert the magnetised point through a few threads of the
material. All that we now have to do is to soften the gum a little and
then dab the thing at once on the Mason-bee's back, so that the broken
needle runs parallel with the spine. Other engines of the same kind
are prepared and due note taken of their poles, so as to enable me to
point the south pole at the insect's head in some cases and at the
opposite end in others.

My assistant and I begin by rehearsing the performance; we must have a