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Document number: 1677
Date: Mon 19 May 1828
Postmark: 20 May 1828
Recipient: TALBOT William Henry Fox
Author: YOUNG Thomas
Collection: British Library, London, Manuscripts - Fox Talbot Collection
Last updated: 28th January 2013

Park Square

My dear Sir

I can only repeat my suspicion that some of our organs must be differently constituted from those of some others <1> – Herschel <2> agrees with me in the effect of snapdragon: but in this there may be some falacy, from the want of actual red to show the cheeks and the lips: but when I look at the spectrum as I have coloured it, and compare the figure with Fraunhofer’s <3> I cannot persuade myself that we have been painting from the same original – I have not examined the flame of cyanogen: I conclude you are well acquainted with that of the bottom of a candle which is very striking – I suppose the theatrical light is from tin. Is the pale light of cyanogen beyond the common spectrum?

I shall be truly glad to see your investigations in print – and as Fresnel’s <4> outlines are now nearly finished in Brande <5> this would form a very good continuation of the subject.

Your words were “Just so will any number [destroy each other] if equidistant, except in one case – when they all strengthen each other” and you now say, that the sum of the sines is finite only when x = 0, 360º, &c” –

My observation was that when the number is finite the sum is not = 0 in cases like that which I mentioned –

I am still at a loss to conceive how you get an infinite number, or even a very large number of centres of divergence in perfect accordance But I must wait for your paper.

I have nothing to do with force, inversely as the distance – we have problems enough, in all conscience, that are natural without adding artificial ones –

Believe me Dear Sir very truly yours
Thomas Young

H. Fox Talbot Esq
31 Sackville Street


1. See Doc. No: 01668.

2. Sir John Frederick William Herschel (1792–1871), astronomer & scientist.

3. Joseph von Fraunhofer (1787–1826), optician, Munich.

4. Augustine Jean Fresnel (1788–1827), French physicist.

5. William Thomas Brande edited the Quarterly Journal of Science, Literature and the Arts for the Royal Institution and the journal (which had varying titles) was often referred to as his.

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