rface being
emitted from its relaxed pores attracts bodies. And if it be an effusion
does it seize upon the air whose motion the bodies follow, or upon the
bodies themselves? But if amber allured the body itself, then what need
were there of friction, if it is bare and smooth? Nor does the force arise
from the light which is reflected from a smooth and polished body; for a
Gem of Vincent's rock[138], Diamond, and clear glass, attract when they are
rough; but not so powerfully and quickly, because they are not so readily
cleansed from extraneous moisture on the surface, and are not rubbed
equally so as to be copiously resolved at that part. Nor does the sun by
its own beams of light and its rays, which are of capital importance in
nature, attract bodies in this way; and yet the herd of philosophizers
considers that humours are attracted by the sun, when it is only denser
humours that are being turned into thinner, into spirit and air; and so by
the motion of effusion they ascend into the upper regions, or the
attenuated exhalations are raised up from the denser air. Nor does it seem
to take place from the effluvia attenuating the air, so that bodies
impelled by the denser air penetrate towards the source of the rarefaction;
in this case both hot and flaming bodies would also allure other bodies;
but not even the lightest chaff, or any versorium moves towards a flame. If
there is a flow and rush of air towards the body, how can a small diamond
of the size of a pea[139] summon towards itself so much air, that it seizes
hold of a biggish long body placed in equilibrio (the air about one or
other very small part of an end being attracted)? It ought also to have
slopped or moved more slowly, before it came into contact with the body,
especially if the piece of amber was rather broad and flat, from the
accumulation of air on the surface of the amber and its flowing back again.
If it is because the effluvia are thinner, and denser vapours come in
return, as in breathing, then the body would rather have had a motion
toward the electrick a little while after the beginning of the application;
but when electricks which have been rubbed are applied quickly to * a
versorium then especially at once they act on the versorium, and it is
attracted more when near them. But if it is because the rarefied {55}
effluvia produce a rarefied medium, and on that account bodies are more
prone to slip down from a denser to a more attenuated medium; t