The experimental researches of Faraday are so voluminous,
their descriptions are so detailed, and their wealth of illustration
is so great, as to render it a heavy labour to master them.
The multiplication of proofs, necessary and interesting when the new
truths had to be established, are however less needful now when
these truths have become household words in science. I have
therefore tried in the following pages to compress the body, without
injury to the spirit, of these imperishable investigations, and to
present them in a form which should be convenient and useful to the
student of the present day.

While I write, the volumes of the Life of Faraday by Dr. Bence
Jones have reached my hands. To them the reader must refer for an
account of Faraday's private relations. A hasty glance at the work
shows me that the reverent devotion of the biographer has turned to
admirable account the materials at his command.

The work of Dr. Bence Jones enables me to correct a statement
regarding Wollaston's and Faraday's respective relations to the
discovery of Magnetic Rotation. Wollaston's idea was to make the
wire carrying a current rotate round its own axis: an idea
afterwards realised by the celebrated Ampere. Faraday's discovery
was to make the wire carrying the current revolve round the pole of
a magnet and the reverse.

John Tyndall.
Royal Institution:
December, 1869.