SIR, -- I have been lately honored with your letter of September the 24th, 1788, accompanied by a diploma for a Doctorate of Laws, which the University of Harvard has been pleased to confer on me. Conscious how little I merit it, I am the more sensible of their goodness and indulgence to a stranger, who has had no means of serving or making himself known to them. I beg you to return them my grateful thanks, and to assure them that this notice from so eminent a seat of science, is very precious to me.

The most remarkable publications we have had in France, for a year or two past, are the following. `Les voyages d'Anacharsis par l'Abbe Barthelemi,' seven volumes, octavo. This is a very elegant digest of whatever is known of the Greeks; useless, indeed, to him who has read the original authors, but very proper for one who reads modern languages only. The works of the King of Prussia. The Berlin edition is in sixteen volumes, octavo. It is said to have been gutted at Berlin; and here it has been still more mangled. There are one or two other editions published abroad, which pretend to have rectified the maltreatment both of Berlin and Paris. Some time will be necessary to settle the public mind, as to the best edition.

Montignot has given us the original Greek, and a French translation of the seventh book of Potolemy's great work, under the title of `Etat des etoiles fixes au second siecle,' in quarto. He has given the designation of the same stars by Flamstead and Beyer, and their position in the year 1786. A very remarkable work is the `Mechanique Analytique,' of Le Grange, in quarto. He is allowed to be the greatest mathematician now living, and his personal worth is equal to his science. The object of his work is to reduce all the principles of mechanics to the single one of the equilibrium, and to give a simple formula applicable to them all. The subject is treated in the algebraic method, without diagrams to assist the conception. My present occupations not permitting me to read any thing which requires a long and undisturbed attention, I am not able to give you the character of this work from my own examination. It has been received with great approbation in Europe. In Italy, the works of Spallanzani on digestion and generation, are valuable. Though, perhaps, too minute, and therefore tedious, he has developed some useful truths, and his book is well worth attention; it is in four volumes, octavo. Clavigaro, an Italian also, who has resided thirty-six years in Mexico, has given us a history of that country, which certainly merits more respect than any other work on the same subject. He corrects many errors of Dr. Robertson; and though sound philosophy will disapprove many of his ideas, we must still consider it as an useful work, and assuredly the best we possess on the same subject. It is in four thin volumes, small quarto. De la Land has not yet published a fifth volume.

The chemical dispute about the conversion and reconversion of air and water, continues still undecided. Arguments and authorities are so balanced, that we may still safely believe, as our fathers did before us, that these principles are distinct. A schism of another kind, has taken place among the chemists. A particular set of them here, have undertaken to remodel all the terms of the science, and to give to every substance a new name, the composition, and especially the termination of which, shall define the relation in which it stands to other substances of the same family. But the science seems too much in its infancy as yet, for this reformation; because, in fact, the reformation of this year must be reformed again the next year, and so on, changing the names of substances as often as new experiments develope properties in them undiscovered before. The new nomenclature has, accordingly, been already proved to need numerous and important reformations. Probably it will not prevail. It is espoused by the minority only here, and by very few, indeed, of the foreign chemists. It is particularly rejected in England.