tention of answering them,
fully and confidentially; but you know such a correspondence between
you and me cannot pass through the post, nor even by the couriers
of ambassadors. The French packet-boats being discontinued, I am now
obliged to watch opportunities by Americans going to London, to write
my letters to America. Hence it has happened, that these, the sole
opportunities by which I can write to you without fear, have been lost,
by the multitude of American letters I had to write. I now determine,
without foreseeing any such conveyance, to begin my letter to you,
so that when a conveyance occurs, I shall only have to add recent
occurrences. Notwithstanding the interval of my answer which has taken
place, I must beg a continuance of your correspondence; because I
have great confidence in your communications, and since Mr. Adams's
departure, I am in need of authentic information from that country.

I will begin with the subject of your bridge, in which I feel myself
interested; and it is with great pleasure that I learn, by your favor
of the 16th, that the execution of the arch of experiment exceeds
your expectations. In your former letter you mention, that, instead of
arranging your tubes and bolts as ordinates to the cord of the arch, you
had reverted to your first idea, of arranging them in the direction of
radii. I am sure it will gain both in beauty and strength. It is true
that the divergence of these radii recurs as a difficulty, in getting
the rails on upon the bolts; but I thought this fully removed by the
answer you first gave me, when I suggested that difficulty, to wit, that
you should place the rails first, and drive the bolts through them,
and not, as I had imagined, place the bolts first, and put the rails on
them. I must doubt whether what you now suggest will be as good as
your first idea; to wit, to have every rail split into two pieces
longitudinally, so that there shall be but the halves of the holes in
each, and then to clamp the two halves together. The solidity of this
method cannot be equal to that of the solid rail, and it increases the
suspicious parts of the whole machine, which, in a first experiment,
ought to be rendered as few as possible. But of all this the practical
iron men are much better judges than we theorists. You hesitate between
the catenary and portion of a circle. I have lately received from Italy
a treatise on the equilibrium of arches, by the Abbe Mascheroni. It
appears