The memoir was written under great pressure, but I am not ashamed of it as it stands.
Glimpses of Faraday's character and gleams of his discoveries are there to be found which will be of interest to humanity to the end of time.
John Tyndall.

Hind Head, December, 1893.
[Note .-- It was, I believe, my husband's intention to substitute this Preface, written a few days before his death, for all former Prefaces.

As, however, he had not the opportunity of revising the old prefatory pages himself, they have been allowed to remain just as they stood in the last edition.
Louisa C.Tyndall.].