Believes that the operative rays in JH's thermographic process are neither 'calorific' nor 'thermal'.
Showing 61–73 of 73 items
Believes that the operative rays in JH's thermographic process are neither 'calorific' nor 'thermal'.
Clarification of priority to the prismatic analysis of the Daguerreotype photograph; comments on the location of a limiting diaphragm in a camera obscura.
Will forward RH's paper to the R.S.L.; intrigued by RH's results using mercury vapor to produce the image on exposed paper.
Unable to give any specifics concerning Louis Jacques Mandé Daguerre's new photographic process. Discovered that old paper specimens produced a much better representation of the spectrum in its natural colors than those obtained at the date of JH's paper; these results are 'light on a dark ground,' which makes JH more hopeful that colored photography will someday be perfected. Has experimented with vegetable substances.
Sends RH a packet of photographs with a description of each type.
Some comments about photographic processes and about RH's observations of the heavens [see RH's 1843-3-24].
Read John William Draper's papers; although he believes that Draper's instruments are inconsistent, JH feels that they are still important because they are measurable. Decries [L. F.] Moser's skepticism of photography's value, calling it a 'blindfolding to some of the most interesting physical relations that have ever been discovered.'
Sorry to hear RH has been ill; JH sends some photographic examples.
Comments on RH's chromatype photographic process and other processes tried by JH.
Hopes that his paper does not anticipate any of RH's work; will share with the R.S.L. any of RH's results. Laments that he is unable to fix the spectral colors on photographic paper. Asks if RH has studied the bromines.
Expresses his pleasure at RH's new position at the Museum of Economic Geology.
Wishes to discuss an urgent matter.
Asks to borrow a book.