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Darwin Correspondence Project

To Robert Hunt   22 July [1855]

Down Farnborough Kent

July 22d

My dear Sir

I thank you most sincerely for your glass-specimens, (which will be of the greatest use to me) & for your very kind letter.1 The latter came quite in time; for I have only finished a few days ago, your very interesting volume (2d. Edit) on Light.—2 The chapter on the relation of light & actinism towards plants is most suggestive,3 & I had determined on trying the 3 viz blue, red & yellow, which you have sent me. But I want extremely to beg one other favour, viz where can I get such glasses.? I have not the least idea where to try?

Do you know with what the Blue & Red (& yellow) (which I think will be the most valuable to me) are coloured; as this, perhaps, would be an aid in getting the right sorts; for I infer from what you say, that the mere colour is not always a safe guide in regard to the power of the glass in intercepting the radiant powers.

After I have been to some glass place, would you permit me to show you any specimens, the manufacturer may have by them? I shall be in London on 7th, 8th & 9th of August, & with your permission will call & show you any glass which I could meet with. If you will send me a line about glass manufacturers you will complete your kindness, for which I am really very much obliged to you.

Pray believe me | My dear Sir | Your’s sincerely | Charles Darwin


Letter from Robert Hunt, 19 July 1855.
R. Hunt 1854.
R. Hunt 1854, pp. 215–47. These pages are annotated in CD’s copy; on p. 237, CD noted: ‘Make Hybrids under red glass.’


Mentions RH’s book on light [Researches on light in its chemical relations, 2d ed. (1854)]. Asks about coloured glass used in experiments on plants.

Letter details

Letter no.
Charles Robert Darwin
Robert Hunt
Sent from
Source of text
American Philosophical Society (B/D25.287)
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 1727,” accessed on 26 June 2019,

Also published in The Correspondence of Charles Darwin, vol. 5