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Forbes, James David in addressee 
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Herschel3521

From:
Sir John Herschel
To:
James David Forbes
Date:
[3 March 1840]
Source of text:
St. Andrews 12 (C: RS:HS 25.6.1 & TxU:H/L-0157; Reel 1054)
Summary:

Outlines theory behind and method for preparing thermographic paper, which allows observers to determine 'what share each ray of the spectrum bears in producing the observed total effects.'

Contributor:
John Herschel Project

Herschel3595

From:
Sir John Herschel
To:
James David Forbes
Date:
[13 March 1840]
Source of text:
St. Andrews 13 (C: RS:HS 22.44)
Summary:

On the preparation of paper to exhibit a thermal spectrum.

Contributor:
John Herschel Project
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