and contracts for the want of it.  If the right hand piece be the cross-grained one, when the air is very moist, it lengthens, and forces its companion to form a kind of interior annulus of a circle on the left.  When the air is dry, it contracts, draws its companion to the right, and becomes itself the interior annulus.  In order to show this dilation and contraction, an index is fixed on the upper end of the two slips; a plate of metal or wood is fastened to the front of the plinth, so as to cover the two slips from the eye.  A slit, being nearly the portion of a circle, is cut in this plate, so that the shank of the index may play freely through its whole range.  On the edge of the slit is a graduation.  The objection to this instrument is, that it is not fit for comparative observations, because no two pieces of wood being of the same texture exactly, no two will yield exactly alike to the same agent.  However, it is less objectionable on this account, than most of the substances used.  Mr. Rittenhouse had a thought of trying ivory:  but I do not know whether he executed it.  All these substances not only vary from one another at the same time, but from themselves at different times.  All of them, however, have some peculiar advantages, and I think this, on the whole, appeared preferable to any other I had ever seen.  Not knowing whether you had heard of this instrument, and supposing it would amuse you, I have taken the liberty of detailing it to you.

I beg you to be assured of the sentiments of perfect esteem and respect with which I have the honor to be, Sir, your most obedient

and most humble servant,

Th:  Jefferson.

LETTER XXXVII.—­TO JOHN JAY, December 31, 1786

TO JOHN JAY.

Paris, December 31, 1786

Sir,

I had the honor of addressing you on the 12th of the last month; since which your favor of October the 12th has been received, enclosing a copy of the resolution of Congress for recalling Mr. Lambe.  My letter by Mr. Randall informed you, that we had put an end to his powers, and required him to repair to Congress.  I lately received a letter from him, dated Alicant, October the 10th, of which I have the honor to enclose you a copy:  by which you will perceive, that the circumstance of ill health, either true or false, is urged for his not obeying our call.  I shall immediately forward the order of Congress.  I am not without fear, that some misapplication of the public money may enter into the causes of his declining to return.  The moment that I saw a symptom of this in his conduct, as it was a circumstance which did not admit the delay of consulting Mr. Adams, I wrote to Mr. Carmichael, to stop any monies which he might have in the hands of his banker.  I am still unable to judge whether he is guilty of this or not, as by the arrangements with Mr. Adams, who alone had done business with the bankers of the United