University of Virginia Library

TO THOMAS JEFFERSON.

Dear Sir,—My journey from Annapolis was so
retarded by rains and their effect on the water courses
that I did not complete it till the ninth day after I left
you. I took[2] Col. Mason in my way & had an
evening's conversation with him. I found him much
less opposed to the general impost than I expected.
Indeed he disclaimed all opposition to the measure itself
but had taken up a vague apprehension that if
adopted at this crisis it might embarrass the defence
of our trade agst British machinations, he seemed
upon the whole to acquiesce in the territorial cession,

but dwelt much on the expediency of the guaranty.
On the article of a convention for revising our form
of Government he was sound and ripe and I think
would not decline a participation in the work. His
heterodoxy lay chiefly in being too little impressed with
either the necessity or the proper means of preserving
the confederacy.

The situation of the commerce of this country as
far as I can learn is even more deplorable than I had
conceived. It cannot pay less to Philada. & Baltimore
if one may judge from a comparison of prices here &
in Europe, than 30 or 40 Per Ct. on all the exports &
imports, a tribute which if paid into the treasury of
the State would yield a surplus above all its wants.
If the Assembly should take any steps towards its
emancipation you will no doubt be apprized of them
as well as their other proceedings from Richmond.

I am not yet settled in the course of law reading
with which I have tasked myself and find it will be
impossible to guard it against frequent interruptions.
I deputed one of my brothers to Monticello with
the draught on your library, but Capt. Key was
down at Richmond. As soon as he returns I propose to
send again. My Trunk with Buffon &c. has come
safe to Fredg. so that I shall be well furnished with
materials for collateral reading. In conversing on
this author's Theory of central heat I recollect that
we touched upon as the best means for trying its
validity,[3] the comparative distances from the earths

center of the summits of the highest mountains and
their bases or the level of the sea. Does not the
oblate figure of the earth present a much more extensive
and perhaps adequate field for experiments?
According to the calculations of Martin grounded on
the data of Manpertius &c.      

The Equatorial diameter of the Earth is	7942.2	Eng. Miles
The polar diam:	7852.4	E.M.
difference between eq: & pol. diameter	89.8.	E.M.

The difference then of the semidiameters is 44.9, E.
miles, that is 1/87.94 the mean semidiameter calling
this difference in round numbers 45 miles, and disregarding
the small variations produced by the elliptical
form of the Earth, the radii will be shortened 1/2 of a
mile by each degree from the equator to the poles.
It would seem therefore that the difference of distance
from the center at the Equator & at the highest
latitude that may [be] visited must be sufficient to produce
a discoverable difference in the degrees of any heat
emitted equally in every direction from the center:
and the experiment might be sufficiently diversified
to guard against illusion from any difference which
might be supposed in the intermediate density of
different parts of the Earth. The distance even between
the Equator & the polar circle produces a
difference of no less than 33 1/6 miles i.e. 1/119 of the
mean distance from the center; so that if the curiosity
of two setts of French Philosophers employed in
ascertaining the figure of the earth, had been directed
to this question, a very little additional trouble &
expence might perhaps have finally solved it. Nay
the extent of the U.S. computing from the 31° of
lat: to the 45° only makes a difference of 7 miles in
the distance from the center of the Earth; a greater
difference I suppose than is afforded by the highest
mountains or the deepest mines or both put together.

On my delivering you the draught on Mr. Ambler I
remember you put into my hands a note which I
never looked into supposing it to relate to that circumstance
In examining my papers I perceive that
I have lost it and mention it to put you on your
guard in case the note sd. fall into bad hands & be
capable of being abused. Present my respects to
Mr. Mercer & the other gentlemen of the Delegation
& be assured that I am yrs sincerely
You will be so good as to give the inclosed a safe
conveyance to Mrs. House.