PARIS, August 8, 1787.
SIR,--I have duly received your favor of June the 6th, and immediately
communicated its contents to a member of the Academy. He told me that
they had received the other copy of your memorial, which you mention to
have sent through another channel; that your ideas were not conveyed so
explicitly, as to enable them to decide finally on their merit, but
that they had made an entry in their journals, to preserve to you the
claim of the original idea. As far as we can conjecture it here, we
imagine you make a table of variations of the needle, for all the
different meridians whatever. To apply this table to use, in the voyage
between America and Europe, suppose the variation to increase a degree
in every one hundred and sixty miles. Two difficulties occur: 1, a
ready and accurate method of finding the variation of the place; 2, an
instrument so perfect, as that (though the degree on it shall represent
one hundred and sixty miles) it shall give the parts of the degree so
minutely, as to answer the purpose of the navigator. The variation of
the needle at Paris, actually, is 21° west. I make no question you have
provided against the doubts entertained here, and I shall be happy that
our country may have the honor of furnishing the old world what it has
so long sought in vain. I am, with much respect, Sir, your most
obedient humble servant.