Add MS 88942/1/185

This notebook contains mainly astronomical and a few mathematical notes. The notebook contains substantial records of Talbot’s conversations with Dominique Arago at the Paris Observatory from March 1825. Talbot used the large telescope there to observe Jupiter, the Crab nebula and the Orion nebula. Arago and Talbot discussed in detail Arago’s famous experiments on the effect of rotating metal discs on magnetic needles, on sunlight as the result of burning gas, on the equal refrangibility of all starlight, which both Arago and Fraunhofer judged evidence against the particle theory of light and on the polarisation of moonlight.

In June 1825, Talbot recorded experiments at the Royal Institution on coloured flames and his own work on the polarisation of light from a rainbow. The notebook also contains remarks on the design of a heliostat, designed to maintain the orientation of a telescope, and on Augustin Fresnel’s new wave theory of light. It also includes detailed notes on the effect of rotating bodies on a magnetized needle, on photometers and the sun, on magic squares, and a long entry on light, on wave theory of light. The mathematical notes deal with calculations on the difference between hyperbolic arcs and their tangents, some notes on algebraic equations, and includes some excerpts from mathematical books at the end.

The notebook is dated 'March 1825' on the inside front cover in pencil, but this date does not seem to be in Talbot's hand and appears to have been added at a later date.

Notebook started: Mar 1825. Designated 'C' on outside and inside front cover.