My dear Sir
I have taken the liberty of enclosing a letter for one of my Sons, & beg that you will have the goodness to frank it to him,<1> as it is more than a Double one.
I have just sent off to Mr Taylor <2> a Paper on Accidental Colours <3> in which I have proved that the Direct and accidental impression are contemporaneous, which is hostile to the Theory of these colours just published in the Ann. de Chimie by M. Plateau of Brussels. <4>
I have observed a curious fact that a small blow on the head makes the accidental colour suddenly disappear. – I suspected that the vibrations of a powerful Gong wd communicate a tremor to the head which would extinguish the accidental impression, but I have just tried it, and it produces no effect.
I am, My Dear Sir, Ever Most truly yrs
H.F. Talbot Esqr
&c &c &c
1. As an MP, WHFT had franking privileges and was entitled to free postage. Members commonly gave signed covers or envelopes to friends. At the time, the recipient paid for postage (to ensure that the letter was delivered). This arrangement was withdrawn in January 1840 with the introduction of the Penny Post, which instituted uniform costs and pre-paid stamps.
2. Richard Taylor (1781–1858), publisher & naturalist.
3. D. Brewster, ‘Account of two experiments on Accidental Colours; with observations on their theory’. Philosophical Magazine v. 4, 1834, pp. 353–334.
4. Joseph Plateau (1801–1883), ‘Sur le Phénomène des Couleurs accidentelles’, Annales de Chimie et de Physique, s. 2 v. 53, 1833, pp. 386–398.