The two letters here reproduced represent one side of an exchange of four letters between John Quincy Adams and his father during the period when both John Quincy and his brother Charles were enrolled in M. Pechigny's school at Passy, variously called (as the covers show) an “Ecole de Mathematiques” and a “Pension de Mathematiques.” The texts indicate, however, that the school offered a regular classical curriculum. The books and other topics mentioned in the letters have been annotated under the letters themselves (16 and 21 March 1780, below; see also John Adams' prompt and decisive replies of 17 and 22 March respectively, and No. 12 in the present Descriptive List).

But apart from their substance and the striking contrast between the two letters in respect to John Quincy's handwriting (following his father's injunction of 17 March), the letters have a special interest because of their postal markings. These illustrate with remarkable detail and clarity the workings of the highly efficient “petite poste de Paris,” inaugurated in 1760 for the carriage of mail within the city and suburbs. There were nine collections a day throughout the entire area, which was divided into a network of postal districts and routes between them. Both the day of the month (“16” and “21”) and the particular collection (4th and 8th “Levées”) were stamped on the cover at the sorting stage. The next mark affixed was that which appears within the circle on the cover, in both these cases “K/EI.” This was the coded mark of the “facteur” (postman or postal supervisor) in the principal place in the suburbs where letters were delivered from the surrounding localities. K stands for the bureau or office handling all mail from the suburbs, E and I for a particular district and subdistrict respectively (in this case Passy). The “BANLIEU” stamp was also added at this point on the letter of the 16th, signifying that it was a letter from the suburbs; its absence on the letter of the 21st, according to a modern authority on French postal history, “n'est pas étonnant . . . car on ne l'apposait que de façon très irregulière.” The final stamp, “E/P.D,” represents the post office within the city where the letter was to be delivered: E being the code name for the postal district centered on the Rue Saint-Honoré, embracing the Rue de Richelieu, and P.D being the “port dû” or postage due at that point, to be paid by the recipient (in this case, as hand-supplied on the letter of the 16th, three sols or sous, the normal rate from the xviiisuburbs). The amount of postage due is apparently omitted from the letter of the 21st. What looks like a “2” cannot be right for the postage and may be a squiggle by John Quincy, perhaps part of an “A” preceding the word “Monsieur.”

The above account is based in part on the excellent contemporary discussion in Hurtaut and Magny, Dictionnaire historique de la ville de Paris et de ses environs . . ., Paris, 1779, 4:132–133; it also owes much to an explanation of the postmarked covers of J. Q. Adams' letters kindly furnished to the editors by M. Rémi Mathieu, of the Archives of France, in a letter of 12 June 1967.