Faraday, you have been informed, endeavoured to improve the
manufacture of glass for optical purposes. But though he produced a
heavy glass of great refractive power, its value to optics did not
repay him for the pains and labour bestowed on it. Now, however,
we reach a result established by means of this same heavy glass,
which made ample amends for all.

In November, 1845, he announced his discovery of the 'Magnetization
of Light and the Illumination of the Lines of Magnetic Force.'
This title provoked comment at the time, and caused misapprehension.
He therefore added an explanatory note; but the note left his meaning
as entangled as before. In fact Faraday had notions regarding the
magnetization of light which were peculiar to himself, and
untranslatable into the scientific language of the time. Probably
no other philosopher of his day would have employed the phrases just
quoted as appropriate to the discovery announced in 1845.
But Faraday was more than a philosopher; he was a prophet, and often
wrought by an inspiration to be understood by sympathy alone.
The prophetic element in his character occasionally coloured,
and even injured, the utterance of the man of science; but
subtracting that element, though you might have conferred on him
intellectual symmetry, you would have destroyed his motive force.

But let us pass from the label of this casket to the jewel it contains.
'I have long,' he says, 'held an opinion, almost amounting to
conviction, in common, I believe, with many other lovers of natural
knowledge, that the various forms under which the forces of matter
are made manifest have one common origin; in other words, are so
directly related and mutually dependent, that they are convertible,
as it were, into one another, and possess equivalents of power in