ssantly took them down, as an architect
removes the scaffolding when the edifice is complete. 'I cannot but
doubt,' he says, 'that he who as a mere philosopher has most power of
penetrating the secrets of nature, and guessing by hypothesis at her
mode of working, will also be most careful for his own safe progress
and that of others, to distinguish the knowledge which consists of
assumption, by which I mean theory and hypothesis, from that which is
the knowledge of facts and laws.' Faraday himself, in fact, was
always 'guessing by hypothesis,' and making theoretic divination the
stepping-stone to his experimental results.

I have already more than once dwelt on the vividness with which he
realised molecular conditions; we have a fine example of this strength
and brightness of imagination in the present 'speculation.' He grapples
with the notion that matter is made up of particles, not in absolute
contact, but surrounded by interatomic space. 'Space,' he observes,
'must be taken as the only continuous part of a body so constituted.
Space will permeate all masses of matter in every direction like a net,
except that in place of meshes it will form cells, isolating each atom
from its neighbours, itself only being continuous.'

Let us follow out this notion; consider, he argues, the case of a
non-conductor of electricity, such for example as shell-lac, with its
molecules, and intermolecular spaces running through the mass. In its
case space must be an insulator; for if it were a conductor it would
resemble 'a fine metallic web,' penetrating the lac in every direction.
But the fact is that it resembles the wax of black sealing-wax, which
surrounds and insulates the particles of conducting carbon, interspersed
throughout its mass. In the case of shell-lac, therefore, space is an
insulator.

But now, take the case of a conducting metal. Here we have, as before,
the swathing of space round every atom. If space be an insulator there
can be no transmission of electricity from atom to atom. But there is
transmission; hence space is a conductor. Thus he endeavours to hamper
the atomic theory. 'The reasoning,' he says, 'ends in a subversion of
that theory altogether; for if space be an insulator it cannot exist
in conducting bodies, and if it be a conductor it cannot exist in
insulating bodies. Any ground of reasoning,' he adds, as if carried away
by the ardour of argument, 'which tends to such conclusions as these
must in itself