May 22d 1854
My dear Sir
I thought I might meet you at Lord Rosse’s <2> on Saturday evening. I have some difficulties with regard to the affidavit <3> you have sent me. Though I am acquainted with the processes you have invented generally I do not sufficiently bear in mind what you have claimed in your patent and what you had previously given to the public, and I have no copy of the specification to refer to in order to satisfy myself in this respect.
It might be inferred, from the words of the affidavit,<4> that I intended to attribute to you generally the rendering a surface sensitive to light by preparing it with a solution of nitrate of silver, and the development of an invisible image; whereas these processes are common to the Daguerrotype. It appears to me that your substantial claims are, 1st the developing an invisible image of a negative picture for the purpose afterwards of producing and multiplying positive pictures, and 2d the specific employment of gallic acid to effect this purpose.
I am very much engaged
and at present and very little in town. I shall be at the Atheneum <5> on Thursday between 4 and 5 o’clock, and if you will let me previously know will meet you there at any earlier hour on that day. I have spoken to Dr Miller <6> of King’s College, who thoroughly understands the subject, and he has no objection to give you his assistance in any subsequent proceedings.
Yours very truly
2. William Parsons, 3rd Earl of Rosse (1800–1867), astronomer & MP
3. Talbot was securing affadavits to support his claim that the principle of the collodion process was covered by his Calotype patent. This particular case verses James Henderson was brought before the Court of Chancery in 1854.
4. WHFT sought affidavits from friends and colleagues, supporting his contention that he was the true inventor of negative/positive photography. In the end, he published ones from Sir David Brewster and Sir John Herschel.
5. Athenaeum Club, Pall Mall, London: WHFT’s club; a gentleman’s club composed primarily of artists and scientists
6. Professor William Allen Miller (b. 1817), physician & chemist