Search: Herschel, John in correspondent 
Forbes, James David in correspondent 
1840-1849::1840::03 in date 
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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

Herschel3614

From:
James David Forbes
To:
Sir John Herschel
Date:
[9 March 1840]
Source of text:
St. Andrews LB III 71, 72 (C: RS:HS 7.295)
Summary:

Would like to know the degree of sensibility to heat of JH's paper. The paper of W. H. F. Talbot is useless for his purpose as only violet heat affects it. Did JH use a flint glass prism for his spectrum experiments? Has he ever used photography to show the impression of polarization and diffraction?

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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