The very favourable reception which my book has met with, both from the press and the public, seems to call for my grateful acknowledgment on the issue of a second edition.

In revising the former, I have added some further particulars about Faraday, especially in regard to "his method of working;" and an engraving from a photograph by Watkins, which best recalls to my recollection the features and the usual expression of the genial philosopher.