Dear Sir,

I wrote you last on the 25th of September. Since that I have received
yours of October the 25th, enclosing a duplicate of the last invented
tongue for the harpsichord. The letter enclosing another of them, and
accompanied by newspapers, which you mention in that of October the
25th, has never come to hand. I will embrace the first opportunity of
sending you the crayons. Perhaps they may come with this, which I think
to deliver to Mr. Bingham, who leaves us on Saturday, for London. If, on
consulting him, I find the conveyance from London uncertain, you shall
receive them by a Mr. Barrett, who goes from hence for New York, next
month. You have not authorized me to try to avail you of the new tongue.
Indeed, the ill success of my endeavors with the last does not promise
much with this. However, I shall try. Houdon only stopped a moment, to
deliver me your letter, so that I have not yet had an opportunity of
asking his opinion of the improvement. I am glad you are pleased with
his work. He is among the foremost, or, perhaps, the foremost artist in
the world.

Turning to your _Encyclopedie, Arts et Metiers_, tome 3, part 1, page
393, you will find mentioned an instrument, invented by a Monsieur
Renaudin, for determining the true time of the musical movements, largo,
adagio, &c. I went to see it. He showed me his first invention; the
price of the machine was twenty-five guineas: then his second, which
he had been able to make for about half that sum. Both of these had
a mainspring and a balance-wheel, for their mover and regulator. The
strokes are made by a small hammer. He then showed me his last, which is
moved by a weight and regulated by a pendulum, and which cost only-two
guineas and a half. It presents, in front, a dial-plate like that of
a clock, on which are arranged, in a circle, the words _largo, adagio,
andante, allegro, presto_. The circle is moreover divided into fifty-two
equal degrees. _Largo_ is at 1, _adagio_ at 11, _andante_ at 22,
_allegro_ at 36, and _presto_ at 46. Turning the index to any one of
these, the pendulum (which is a string, with a ball hanging to it)
shortens or lengthens, so that one of its vibrations gives you a crochet
for that movement. This instrument has been examined by the academy of
music here, who were so well satisfied of its utility, that they have
ordered all music which shall be printed here, in future, to have the
movements numbered in correspondence with this plexi-