Edison light bulb and one page of his notes – £60,000 at Christie’s.

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Sold for £60,000 at Christie’s (25/20/13.5% buyer’s premium) these six leaves, extracted from a ruled notebook dated March 1886, were accompanied by an Edison light bulb of 1880-81.

It was, however, only last November that Aguttes of Paris sold this very lot for €45,000 (then £38,795).

Sold at £3500 in the London summer sale was Percival Lowell’s 1915 Memoir on a trans-Neptunian planet, an illustrated offprint in original wrappers from the Memoirs of the Lowell Observatory.

The paper sparked a search for a planet beyond Neptune that eventually culminated in the 1930 discovery of Pluto by Clyde Tombaugh at the Lowell Observatory. This special copy bore the ownership inscription of both men.

Cat trick

Bid to £18,000 at the online sale that ended on July 16 was a six-page letter of 1925 in which the Nobel prize-winning Austrian-Irish physicist Erwin Schrödinger tells his correspondent, Wilhelm Wien: “Just now a new atomic theory is niggling me. If only I knew more mathematics! I am very optimistic about this thing and hope that if only I can master the calculations, it will be very fine.”

Schrödinger is perhaps best known for formulating the Schrödinger’s cat thought experiment, in which very small-scale quantum mechanical events can affect large-scale objects, such as a cat.

All these prices were dwarfed by the sum required to secure a rare four-motor Enigma cypher machine produced by the Olympia Büromaschinenwerke in 1944. It sold at £280,000.