Jan 4/26 by Post Mark ^<1>
31 Sackville S^{t <2>}

Dear Sir

The account of D^r Balfour ^<3> of the effect of the moon on the human body in India, occupies the first 34 pages of the 8^th vol. of Asiatic Researches (London Edition)–

Yours truly
H. F. Talbot

In your exp^t of manifesting the magnetic influence of the Moon, by neutralising the Earth’s attraction, how do you guard against the effect of moisture on the string which serves for the axis of motion; do you use a metallic wire? – The following is the passage in Frauenhofer’s ^<4> works which I mentioned to you as having much embarrassed me, and that I doubted the accuracy of his observation. He speaks of the Spectrum afforded by Electrical Light. Gegan das Ende des Farbenbildes im Rothen bemerkt man eine Linie, die nicht sehr hell ist; ihr Licht wird eben so stark gebrochen wie das der hellen Orangen Linie vom Lampenlichte. ^<5>
(Fraunhofer, Bestimmung &c. p. 221)

J.F.W. Herschel Esq’
56 Devonshire Street

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Notes:

1. Written in WHFT’s hand.

2. 31 Sackville Street, London residence of the Feildings, often used as a London base by WHFT.

3. Dr John Hutton Balfour (1808–1884), Scottish botanist, Asiatick researches, or, Transactions of the society instituted in Bengal, for inquiring into the history and antiquities, the arts, sciences, and literature of Asia.

4. Joseph von Fraunhofer (1787–1826), optician, Munich.

5. Towards the end of the spectrum, in the Red, a line is visible, that is not very bright, its light is as strongly refracted as the light of the bright Orange Lines of Lamplight. Fraunhofer, Bestimmung des Brechungs–und Farbenzerstreuungs–Vermögens verschiedener Glasarten in Bezug auf die Vervollkommnung achromatischer Fernröhre (Munich: Burndy, 1817).