Add MS 88942/1/193

This manifold notebook reflects Talbot's broad interests and contains mainly notes on chemistry, with entries on optics, astronomy and mathematics. Talbot solves equations, conic sections, gives references to secondary literature and copies extracts from Euclid's Elements. The notebook includes some analytical geometry, but mainly contains solutions of indefinite integrals relating to papers Talbot published on the subject in 1836 and 1837.

Talbot records his observation of Halley's Comet on 27 August 1835 with a five feet achromatic telescope at Lacock and summarises other observations of Halley's Comet from newspapers. Proud of having recovered the Comet a day before the Royal Observatory, Talbot sent this observation to John Lubbock in London on 30 August and to George Airy in Cambridge on 1 September. Talbot concludes that the Great 1823 Comet described in Olbers’ catalogue (see Add MS 88942/1/186 ) was the same as Comet XXX of Alexandre Pingré’s 1783 catalogue (notebook p. 136).

The notebook includes an early note on 'sciagraphy' (or the art of fixing shadow images directly onto light-sensitive paper) which points towards Talbot's subsequent invention of the negative/positive process of the calotype: 'In the Photogenic or Sciagraphic process, if the paper is transparent, the first drawing may serve as an object, to produce a second drawing, in which the lights and shadows would be reversed' (notebook p. 90).

The notebook also includes notes on: invisible ink (also referred to in notebooks Add MS 88942/1/190 and Add MS 88942/1/191); crystals and solutions; precipitates; an experiment concerning the velocity of light and electric sparks; magnetic instantaneous light; a description of an electromagnetic apparatus; a method for testing the force of an attraction in different parts of a magnetic bar; an electro magnetic apparatus belonging to Watkins; the adhesion of two glass prisms (quoting Becquerel and Opinus on this topic); determining the distribution of magnetism in a plate of iron; electromagnetic rotation, using suspended needles; letters written with commercial ink turning red when washed with weak sulphuric acid; the colours of flowers at Lucerne; and a chamber illuminated with intermittent light. There are further notes on variation in the phantascope, notes about a magnet and a needle, including a variation involving a revolving cylinder carrying several needles, on Iodides, on a series of bent horseshoe magnets circling a rotating cylinder, on a series of cylinders connected with chains, on the distribution of magnetism in a tetrahedron, on the nature of magnetic motion in a particle, absorption spectra, solar phosphorescence, notes on an 'Electromagnetic engine', and on reproducing images and engravings photographically.

Notebook started: 4 Dec 1834, Lacock. Designated 'M' on outside front cover and inside flyleaf.