Dear Sir,
I propose to leave this on Friday morning, & if the information I have received is correct, I shall be at Lacock Abbey on that Evening with the help of the Railways from Birmingham to Cheltenham & from Cirencester to Chippenham.<1>
The following Expt was witnessed by Profr Bessel <2> whose words I copy from his MSS.
“A black plate either of horn or Agate is placed below a polished surface of Silver at a distance of 1/20 inch and remaining there for 10 minutes; the latter (the Silver surface) will receive an impression of the Figures [&c?] upon engraved upon the former, which may be rendered visible by exposing the Silver plate to the vapours either of Water or of Mercury &ca.”
I shall bring with me Mosers Paper <3> in German which you will be able to decypher.
I am Dear Sir, Ever Most Faithfully yrs
D Brewster
Leamington <4>
18 Upper Parade
July 13th 1842
Henry Fox Talbot Esqr
Notes:
1. Friday was 15 July. Chippenham, Wiltshire: largest town near Lacock, 3 miles N.
2. Friedrich Wilhelm Bessel (1784–1846), astronomer.
3. Ludwig Ferdinand Moser (1805–1880), ‘Ueber den Process des Sehens und die Wirkung des Lichts auf alle Körper’, Annalen der Physik und Chemie, v. 56 no. 6, 1842, pp. 177–234. [See Doc. No: 04541].
4. Royal Leamington Spa, near Warwick, southwest of Birmingham, where the Brewsters were staying for Lady Brewster’s health.