Answd May 30 1833 <1>
29 Albemarle St <2>
May [28th? 29th?] <3>1833
Dear Sir,
I do not know whether you are likely to be in Town again during the next 3 weeks, but if you are, I should like to show you an experiment on Newton’s rings <4> which appears to me to be very remarkable. By causing 2 of these rings to interfere, I obtain a vast number of parallel coloured bands at right angles to the line joining their centres, but the most singular thing, and affording a beautiful illustration of the Theory of Interference, is, that by holding the hand in a particular way so as partially to intercept the incident light, the dark part of the rings suddenly become bright, & the bright rings become dark, the colours changing in to such a degree as to give the system of rings a completely new appearance.
I should wish to communicate some account of this to the Royal Society, but am afraid of falling into the error of giving as new what may be already known. I should therefore be much obliged to you if you would inform me whether the conversion of lights into darkness & vice versâ in Newton’s rings has been anywhere described, & also the appearance of the parallel fringes that I have described at the beginning of my letter.
Believe me Dear Sir Yours vy truly
H. F. Talbot
Notes:
1. Annotation added in Herschel’s hand - for his reply, see Doc. No: 02707.
2. WHFT lived at this London address, just down the street from the Royal Institution, for half of April and all of May, 1833.
3. The second number is overwritten and it is unclear which takes precedence. Perhaps WHFT started the letter on the 28th and returned to it the following day?
4. These bands of colour, seen under a variety of conditions, were observed before Sir Isaac Newton (1642–1727), but investigated in Newton, ‘Discourse on Light and Colours’, Opticks, book ii, 1675.