Collingwood <1>
Jan 15/68
My dear Sir
Many thanks for your note <2> & for the information it contains. Of course I was well satisfied that the statement I mentioned must have originated in some misconception & I now see how it arose.
The existence of visible rays extending very far beyond the extreme violet ordinarily supposed to limit the spectrum - and only becoming sensible to the eye in the complete absence of all other light, was observed by me in 1819 and in the account given of those observations in a paper in Phil Tr 1840 Part 1 p §56 the fact of the visibility of rays extending beyond the very utmost of the limit of the received spectrum - as established by those observations is very distinctly described & shewn - It is only the name Lavender assigned to those rays that is there applied - At the close of that paper (1840) however I certainly was not aware that you had previously mentioned the visibility of those ultra spectral rays in /34. My impression is that visibility though in a very feeble degree extends quite to the limit of refrangibility.
Did you ever get a little brochure I posted to you some months back - a Latin version of Schillers Spaziergang <3> If so do me the favour - if you still retain it to correct the following slips - for which at school I suppose I should have suffered in the flesh. - or rather - on second & better thoughts let me send you per Book Post a corrected copy & request you to commit the other to the flames or the Adriatic which ever is most convenient.
Siue flammis siue mari libet Adriano <4>
Believe me my dear sir yours vy ty
JFW Herschel
Notes:
1. Hawkhurst, Kent.
2. Letter not located.
3. See Doc. No: 04773. The first version of this accomplished by Herschel was translated into English: The Walk; Translated in the Original Metre from the German of F. Schiller (Collingwood: for private circulation, 1842).
4. Either to the flames or to the Adriatic Sea.