I return your two Portraits <1> with many thanks. After exhibiting them at my Lecture which was well received, I sent them to Lord Gray <2> who was very anxious to see them; but having laid them up too carefully I did not receive them from his Lordship till this morning. <3>
I have succeeded in obtaining some very important results respecting the polarising structure of the Atmosphere;– the Compensation of polarised light, and the phenomena of thin Plates seen by polarised light, which will form three Papers <6> for the Royal Society.
The results regarding the Atmosphere are very singular. Arago <7> & Babinet <8> each discovered a Neutral point. There are 4 neutral points <9> produced by the opposite actions of Reflexion & Refraction, which are the cause of all the phenomena of atmospheric Polarisation. The Reflective influence predominates in a clear sky; but in cloudy or hazy weather it is often destroyed by the Refractive influence which sometimes predominates over it.
I am Dear Sir Ever Most Truly yrs
Feby 4th 1841
H.F. Talbot Esqr
1. In September 1840, photographic portraiture, in paper processes, had been made possible by the discovery of the calotype process. As copying would have been difficult in the fainting light of winter, WHFT evidently could only afford to lend Brewster these rare specimens. Five early photographic portraits by WHFT can be found in Brewster’s album. For these images see: ‘A Man Standing in a Doorway’, taken 1840 or 1841, reproduced in Graham Smith, Disciples of Light: Photographs in the Brewster Album (Malibu: The J. Paul Getty Museum, 1990), p. 140; ‘Lady Elisabeth Feilding’, taken August 1841, reproduced in Disciples of Light, p. 32; ‘Lady Elisabeth Feilding as Paolina Borghese’, Schaaf 3693, taken 20 April 1842, reproduced in Disciples of Light, p. 136; ‘Workman at Lacock’, taken 9 April 1842, reproduced in Disciples of Light, p. 137; and ‘Nicolaas Henneman’, taken 1842 or 1843, reproduced in Disciples of Light, p. 37.
2. Francis Gray, 14th Lord Gray of Kinfauns, near Perth (1765–1842).
3. At the 1 March 1841 meeting of the St Andrews Literary & Philosophical Society, “Sir David Brewster, exhibited new specimens of Photography, executed under the direction of Mr Fox Talbot of Lacock Abbey.” Minutes, v. 1, 1836–1861, Special Collections, The Library, University of St Andrews.
4. It has been argued that the consequent freedom to practise WHFT’s process in Scotland allowed photography to develop rapidly both as a process and as an art-form, beginning with Brewster and his associates in St Andrews, and from 1843 with Robert Adamson in Edinburgh and his subsequent partnership with David Octavius Hill (1802–1870), Scottish painter. WHFT's encouragement might well have been a factor, but the complex mix of personalities in both St Andrews and Edinburgh was an essential element.
5. That of the calotype.
6. Only two seem to have appeared: D. Brewster, ‘On the phenomena of thin plates of solid and fluid substances exposed to Polarized Light’, Philosophical Transactions of the Royal Society of London 1841, pp. 43–58; and ‘On the compensations of polarized light, with the description of a Polarimeter for measuring degrees of polarization’, Proceedings of the Royal Society of London, v. 4, 1841, pp. 306–307.
7. Dominique François Jean Arago (1786–1853), French physicist, astronomer & man of science.
8. Jacques Babinet (1794–1872), French physicist and astronomer, inventor of the Babinet compensator.
9. See Brewster, ‘On the existence of a new neutral point and two secondary neutral points’, Report of the British Association for the Advancement of Science, 1842, part 2, p. 13.