My dear Sir: Feb. 8, 1860
I have examined and considered the question propounded in your letter accompanying copy of contract in relation Lard Tanks, apparatus &c, and my opinion is that Messrs H. C. Chadsey & Co,  would, as a general proposition, have the right to continue to use the Tanks, apparatus &c, which they have on hand.
The reason why I say ``as a general proposition'' is that I fear the particular phraseology of their contract, deprives them of it. The language of the contract is so explicit, and so oft repeated, that the right to use, ``shall be until the expiration of said patent'' that I fear it will be held that by their contract, they can not have the benefit of the extension.
Much may be said on the other side; and I only mean to say that in my mind the question, on the phraseology of the contract is doubtful, and perhaps is worth trying Yours as ever