e to his speculative writings. On Friday, January 19, 1844,
he opened the weekly evening-meetings of the Royal Institution by a
discourse entitled 'A speculation touching Electric Conduction and the
nature of Matter.' In this discourse he not only attempts the overthrow
of Dalton's Theory of Atoms, but also the subversion of all ordinary
scientific ideas regarding the nature and relations of Matter and Force.
He objected to the use of the term atom:--'I have not yet found a
mind,' he says, 'that did habitually separate it from its accompanying
temptations; and there can be no doubt that the words definite
proportions, equivalent, primes, &c., which did and do fully express all
the facts of what is usually called the atomic theory in chemistry, were
dismissed because they were not expressive enough, and did not say all
that was in the mind of him who used the word atom in their stead.'

A moment will be granted me to indicate my own view of Faraday's
position here. The word 'atom' was not used in the stead of definite
proportions, equivalents, or primes. These terms represented facts that
followed from, but were not equivalent to, the atomic theory. Facts
cannot satisfy the mind: and the law of definite combining proportions
being once established, the question 'why should combination take place
according to that law?' is inevitable. Dalton answered this question by
the enunciation of the Atomic Theory, the fundamental idea of which
is, in my opinion, perfectly secure. The objection of Faraday to Dalton
might be urged with the same substantial force against Newton: it might
be stated with regard to the planetary motions that the laws of
Kepler revealed the facts; that the introduction of the principle of
gravitation was an addition to the facts. But this is the essence of
all theory. The theory is the backward guess from fact to principle;
the conjecture, or divination regarding something, which lies behind
the facts, and from which they flow in necessary sequence. If Dalton's
theory, then, account for the definite proportions observed in the
combinations of chemistry, its justification rests upon the same basis
as that of the principle of gravitation. All that can in strictness be
said in either case is that the facts occur as if the principle existed.

The manner in which Faraday himself habitually deals with his hypotheses
is revealed in this lecture. He incessantly employed them to gain
experimental ends, but he ince