No summary available.
No summary available.
No summary available.
No summary available.
No summary available.
No summary available.
No summary available.
No summary available.
No summary available.
No summary available.
No summary available.
Tells WT about JH developing the thermographic paper which is susceptible to 'calorific' and 'chemical' rays of light.
Comments on the affidavit supplied by WT; will sign most of it but objects to one section.
Clarifies JH's position, by saying that he clearly supports WT as the inventor of the calotype or talbotype, but has reservations about the collodion process.
Sent WT's specimens to J. B. Biot and F. J. D. Arago in Paris. Developed paper sensitive to heat rays of sun 'beyond the spectrum.' Diagram of three spectra: 'luminous, chemical, and thermic.'
Considerable comment on procedure for submitting paper to R.S.L. Urges WT to mention JH's method of washing with hyposulfite. Comments on some photographic experiments of WT.
Expresses reservations about Samuel Brown's work. Apologizes for delay in trying calotype; has done only some vegetable substance trials.
Thanks for specimen of light sensitive paper. Provides hint on the chemical process that Louis Daguerre may have used in his photographic work. Sends specimens of JH's own work.
Describes method of varying the size of photographic images. Praises Talbot's light sensitive paper and suggests improvements regarding it. Complains about persons too ready to seek a patent.
[Responding to WT's 1826-2-7], JH thanks WT for materials sent, makes suggestions regarding WT's upcoming trip to Geneva, and asks WT to deliver a book to [Alfred] Gautier.
[Responding to WT's 1826-3-24], JH concurs with P. S. Laplace's view about the advantage of astronomical observation from high elevations, e.g., from mountains. Comments on telescope prices, a paper by WT, Florence, and JH's plan to visit the Continent.