GRAVITY is the general Endeavour and Tendency of Bodies towards the
Center of the Earth; this is overcome by the Magnet with Regard to Iron,
and by Electricity with Regard to light Substances both in its
Attraction and Repulsion; but I have never been able to discern that
vortical Motion, by which this Effect was said to be brought about by
the late Dr. _Desaguliers_ and others, having no other Conception of its
Manner of acting than as Rays from a Center, which indeed is confirmed
by several Experiments. One of which, very easy to be tried, is, that if
a single downy Seed of Cotton Grass is dropped from a Man's Hand, and in
its Fall comes within the Attraction of the rubbed Tube; the Down of
this Seed, which before seemed to stick together, separates, and forms
Rays round the Center of the Seed: Or if you fasten many of these Seeds
with Mucilage of Gum Arabic, round a Bit of Stick, the Down of them when
electrified, which otherwise hangs from the Stick, is raised up, and
forms a circular Appearance round the Stick. As these light Bodies are
directed in their Motions, only by the Force impressed upon them, and as
their Appearance is constantly _radiatim_, such Appearance by no Means
squares with our Idea of a Vortex. Some have imagined a Polarity also,
when they have observed one end of an excited Glass Tube repel light
Substances, and the other attract them. But this Deception, arising from
the whole Length of the Tube not being excited, but only such Part of it
as has been rubbed; so that as much of the Tube as is held in the Hand,
remains in an unexcited State, and permits light Substances to lie still
thereon, though forcibly repell'd at the other End. This attractive
Power of Electricity acts not only upon Non-electrics, as Leaf-Gold,
Silver, Thread, and such like, but also upon originally Electrics, as
Silk, dry Feathers, little Pieces of Glass and Resin; it attracts all
Bodies, that are not of the same Standard of Electricity, (if I may be
allowed the Expression) as the excited Body from which it proceeds. I
have found no Body however dense, whose Pores are not pervious to
Electricity by a proper Management, not even Gold itself.