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<rdf:Description rdf:about="https://catalogues.royalsociety.org:443/CalmView/record/catalog/HS/25/6/1" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.1/">
  <dc:title>Copy letter, from Sir John Herschel to James David Forbes, dated at Slough</dc:title>
  <dc:description>Copy letter in John Herschel's hand. 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.'</dc:description>
  <dc:date>3 March 1840</dc:date>
</rdf:Description>