Expresses reservations about Samuel Brown's work. Apologizes for delay in trying calotype; has done only some vegetable substance trials.

Thanks for calotypes involving persons engaged in actions. Gives encouragement to WT's planned photographic tour in Germany. JH has been experimenting regarding color photography.

Comments on confusion between observing comet and zodiacal light. Extensive comments on various materials used in a photographic process where negatives change to positives over long time.

Zodiacal light is a real phenomenon. Further comments on negative to positive process. Questions whether WT can define one cometary orbit with two observations.

Thanks for excellent Talbotypes. Notes how few photographs are 'perspective representations on a vertical plane' and suggests how to correct this.

Refers WT to reference work to check WT's experiments [see WT's 1848-2-4]. JH says he will perform no more experiments in physical optics.

Appreciates WT's letter of congratulation on JH's appointment [as Master of the Mint, to the Cambridge Commission?]. Has begun work with Cambridge.

Agrees to WT's use of name 'amphitype' [see WT's 1851-5-6 or earlier].

Wants recommendation from WT for teacher of the 'art of Talbotyping.'

Thanks for examples of WT's photographic engraving; sends a photo in return.

May need WT's permission for the publication in a book on coinage of a photograph of JH prepared using WT's patented process.

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.

Asks WT whether WT made a certain claim about the spectrum of strontium. Recounts observations of the strontium spectrum made by JH in 1822.