Optical and Physical Instrument Maker to
Her Majesty’s Government,
The Royal Observatory, the Royal Society,
and the Observatories of Cambridge, Utrecht, &c., &c.
63, STRAND, W.C. (Manufactory. 6, Vine Street.)
ESTABLISHED 100 YEARS
31 Aug. <printed> 1874
In reply to your esteemed inquiry I presume that the inquiring you have made refers to the double Slit for the Spectroscope which I have made for Sir Chas. Wheatstone <1> – this is our ingenious contrivance for superimposing two spectra one on the other and thus obtaining the resulting colors from the mixture of various parts of the spectrum. The Slit I have made is adapted for use with one of any direct vision spectroscopes, and the price is about £2. 5 exclusive of the Spectroscope.
I have no second-hand Telescopes by me, and could not let out such instruments on hire.
Awaiting your further favors.
John BrowningH.F. Talbot Esq.
1. Sir Charles Wheatstone (1802–1875), scientist.