Your letter of June 4. is received as the former one had been in due time. it was not answered because the effects of age oblige me to withdraw from all correspondence which is not of absolute necessity, and especially on subjects of the difficulty of that your letter presents. I am afraid, you are not aware of all it’s difficulties. there are 3. persons, known to myself, capable of deciding on the merit of your discovery; these are Doctr Patterson of Philadelphia, mr Hasslaer in the service of the US. and mr Bowditch of Salem in Mass. I name these because they are known to me. doubtless there are many others unknown to me. but if, thro’ any friend, you can get the opinion of either of these, you may be assured of it’s correctness in a much higher degree than from any opinion of mine. for the good of mankind as well as of yourself, I wish you entire success in your invention.

Th: Jefferson