Ordnance Map Office
Southampton 8th June 1860
My dear Sir,
I have obtained Mr Carpmael’s opinion upon the question as to whether the use of gum in the process we have called Photo-zincography is an infringement of either of your patents. I sent him the extract of your note which relates to this point, and the account of our process which is printed in my Report to Parliament on the progress of the survey in the year 1859. Mr Carpmael states "I am of opinion that the process carried on at the Ordinance Survey office is not an infringement of either of Mr Talbot’s Patents" –
I thought it better to have this point settled at once by an official reference through the Solicitor to the War Office, as it put it on record and clears the ground for future operations.
With reference to the reductions of the plans by photography, we reduce 16 sheets (which are 3 ft x 2 ft) to the dimensions of 9 inch x 6 inch, so as to make one sheet on the reduced side which is 3 ft x 2 ft.
We can make the reduction perfectly accurately, the question is how to produce a plate with the 16 reduced plans on it – at present we draw the rectangles on a plate and rub down the reduced plan each in its proper place, and then expand the outline – I think it probable that your process might be rendered useful to us, but I do not recommend you to incur any expense or experiments, as I have all the means here that can possibly be required for testing its value for our purposes –
my dear Sir
H. Fox Talbot Esqre