Dear Sir/
My friend Mr Hussey <1> for whom I requested you to order the apparatus from Messrs Utzschneider <2> has sent me the following list of what he expects
2 Rectangular Prisms of Flint glass 0in·5 square
1 Rectangular Do – 1in·2 square
1 Equilateral Prism
2 Lenses 50 or 60 feet focus the least 3in diameter.
3 Achromatic Object glasses 2in diameter & under 12in focal length
15 Plano convex Lenses, of 2, 1, 0·75, 0·5, 0·25, 0·1, 0·05, 0·03, 0·025, 0·02, 0·0166, 1/70, 1/80, 1/90, 1/100 inch focus
15 Do Do Plano concave
“Two or three other things” he adds “were mentioned but I cannot at this moment find the memorandum.” Besides these I have some recollection of having got Mr Hussey to include in his list some rectangular prisms for myself, but I am even worse than Mr H. for I not only cannot find the memorandum, but I can no how call to mind what it was I wanted.
I am at length bringing my article on “Light” <3> to a close and shall send you a copy as soon as it is complete
I should like very much to possess one of the 5 or 6 inch object glasses of that manufactory, but I really have a fancy to mount it myself– Have you any idea of what their present price for such a one would be, and whether they would furnish it alone, or at least with only the tube – & eyepieces & an illuminated wire micrometer? for as to their equatorial stands, I don’t like them, & one can get it put on a polar axis as well here as at Munich. but I have a different contrivance altogether in view.
I remain dear sir yours very truly
JFW Herschel
H.F. Talbot Esqr
A.8. Albany
Piccadilly
London
Notes:
1. Thomas John Hussey (1792-1854), amateur astronomer, rector of Hayes Kent.
2. Joseph von Utzschneider (1763–1840), German instrument maker.
3. This was the article finally published in 1830, John F. W. Herschel, ‘Light’ Encyclopaedia Metropolitana, 2nd division, Mixed Sciences, v. 2, pp. 341–586. The manuscript for this article is dated 1827, St. John’s College, Cambridge.