opportunity I can, of doing it. I shall cheerfully execute your commands
as to the _Encyclopedie_, when I receive them. The price will be only
thirty guineas. About half the work is out. The volumes of your Buffon,
which are spoiled, can be replaced here.

I expect that this letter will be carried by the Mr. Fitzhughs, in
a ship from Havre to Portsmouth. I have therefore sent to Havre some
books, which I expected would be acceptable to you. These are the
_Bibliotheque Physico-oeconomique_, which will give you most of the
late improvements in the arts; the _Connoissance des Terns_ for 1786 and
1787, which is as late as they are published; and some pieces on air and
fire, wherein you will find all the discoveries hitherto made on these
subjects. These books are made into a packet, with your address on
them, and are put into a trunk wherein is a small packet for Mr. Wythe,
another for Mr. Page, and a parcel of books, without direction, for
Peter Carr. I have taken the liberty of directing the trunk to you, as
the surest means of its getting safe. I pay the freight of it here, so
that there will be no new demands, but for the transportation from the
ship's side to Williamsburg, which I will pray you to pay; and as much
the greatest part is for my nephew, I will take care to repay it to you.

In the last volume of the _Connoissance des Terns_, you will find the
tables for the planet Herschel. It is a curious circumstance, that this
planet was seen thirty years ago by Mayer, and supposed by him to be a
fixed star. He accordingly determined a place for it, in his catalogue
of the zodiacal stars, making it the 964th of that catalogue. Bode,
of Berlin, observed in 1781, that this star was missing. Subsequent
calculations of the motion of the planet Herschel show, that it must
have been, at the time of Mayer's observation, where he had placed his
964th star.

Herschel has pushed his discoveries of double stars, now, to upwards
of nine hundred, being twice the number of those communicated in the
Philosophical Transactions. You have probably seen, that a Mr. Pigott
had discovered periodical variations of light in the star Algol. He
has observed the same in the _n_ of Antinous, and makes the period of
variation seven days, four hours, and thirty minutes, the duration of
the increase sixty-three hours, and of the decrease thirty-six hours.
What are we to conclude from this? That there are suns which have their
orbits of revolution