cessary for me to
state that I find both iron and bismuth in such vacua perfectly obedient
to the magnet. From such experiments, and also from general observations
and knowledge, it seems manifest that the lines of magnetic force can
traverse pure space, just as gravitating force does, and as statical
electrical forces do, and therefore space has a magnetic relation of its
own, and one that we shall probably find hereafter to be of the utmost
importance in natural phenomena. But this character of space is not
of the same kind as that which, in relation to matter, we endeavour to
express by the terms magnetic and diamagnetic. To confuse these
together would be to confound space with matter, and to trouble all
the conceptions by which we endeavour to understand and work out a
progressively clearer view of the mode of action, and the laws of
natural forces. It would be as if in gravitation or electric forces,
one were to confound the particles acting on each other with the space
across which they are acting, and would, I think, shut the door to
advancement. Mere space cannot act as matter acts, even though the
utmost latitude be allowed to the hypothesis of an ether; and admitting
that hypothesis, it would be a large additional assumption to suppose
that the lines of magnetic force are vibrations carried on by it, whilst
as yet we have no proof that time is required for their propagation, or
in what respect they may, in general character, assimilate to or differ
from their respective lines of gravitating, luminiferous, or electric
forces.'

Pure space he assumes to be the true magnetic zero, but he pushes his
inquiries to ascertain whether among material substances there may not
be some which resemble space. If you follow his experiments, you will
soon emerge into the light of his results. A torsion-beam was
suspended by a skein of cocoon silk; at one end of the beam was fixed
a cross-piece 1 1/2 inch long. Tubes of exceedingly thin glass, filled
with various gases, and hermetically sealed, were suspended in pairs
from the two ends of the cross-piece. The position of the rotating
torsion-head was such that the two tubes were at opposite sides of,
and equidistant from, the magnetic axis, that is to say from the line
joining the two closely approximated polar points of an electro-magnet.
His object was to compare the magnetic action of the gases in the
two tubes. When one tube was filled with oxygen, and the other with
nitr