Voices of History 2: Arts, Science & Exploration, a new CD set of rare and historic recordings from the British Library, features the only known recording of Lord Kelvin speaking. Unfortunately, no word on what he has to say. It's available on the 28th.
Also newly available: Edison's Conquest of Mars (IEEE review with background info) -- the first full reprint with original illustrations of the unauthorized, serialized technothriller sequel to H.G. Wells's The War of the Worlds, written a year later in 1898 by astronomer and science journalist Garrett P. Serviss.
The novel, a classic example of Edisonade (Victorian and Edwardian era science fiction -- see here for more info on the genre), is primarily about Thomas Edison leading a counter-attack against the Red Scourge of Mars, and features cameo appearances from other famous contemporary scientists, including a "disintegrator-gun-slinging Lord Kelvin."
I haven't read it, but I hope while blasting Martians he gets in some good action lines like "You, like radio, have no future!" or "To measure is to know, but to disintegrate is to DIE!"
UPDATE: I have since read it and added a review.