In the spring of 1779, Franklin had taught Jonathan Williams, Jr., the principles of “moral algebra” to help him resolve one of his most troublesome dilemmas—whether or not to return to America. “By the Way,” Franklin added, “if you do not learn it, I apprehend you will never be married.” Williams protested that where marriage was concerned, his negative column seemed always to outweigh the positive one. Besides, he observed, falling in love was rather like falling into a well, which takes more than algebra to get out of.5

The weightiest elements in Williams’ “negative column” seem not to have had to do with the women themselves, but rather with their formidable fathers, and the probabilities of the match increasing his fortunes. He had first met sixteen-year-old Mariamne Alexander while he, at the age of twenty-four, was in England with Franklin in 1774. Smitten, but timid, he periodically consulted with his great-uncle (even after Franklin had returned to Philadelphia) on the course of their affections and the likelihood that her father might be willing to offer a “reasonable assistance.” The Doctor thought she was a “sweet Girl” and encouraged the romance.6 William Alexander, however, when finally approached by the anxious suitor in 1776, set what seemed to be an insurmountable condition to marriage: that Williams be in possession of two thousand pounds, which Alexander would augment with three thousand more in dowry.7

Within a few weeks of arriving at Nantes in January, 1777, Williams gave up hope of marrying Mariamne (citing the hostilities between their countries) and set his sights on a new alliance: he would enter a business partnership with Jean-Daniel Schweighauser and wed his beautiful second daughter.8 The courtship with Miss Schweighauser (her first name is not known) progressed quickly. By August, Williams, encouraged anew by Franklin, spoke to her father. Once again, the suitor’s “present uncertain situation” led to a chilly reception.9

The following spring Williams, abruptly replaced as American agent at Nantes by his would-be father-in-law, found himself enmeshed in the auditing problems occasioned by Arthur Lee’s trumped-up accusations against his business practices. Disheartened, he considered returning to America.1 Although his relationship with Schweighauser was permanently soured, his romance with the merchant’s daughter survived at least through the end of April, 1779, a month when he also received a visit from his English-born illegitimate son Josiah.2

By late July, when Williams was assured of a favorable judgment in the audit of his accounts, his thoughts returned to Mariamne Alexander. He penned a proposal to her father, to be forwarded by Franklin.3 In mid-August, he left Nantes and journeyed to the Alexanders’ home in St.-Germain, stopping along the way and writing his parents of his matrimonial intentions.4 For reasons which remain unclear, William Alexander was now receptive to the proposal. And so—it seems—was his daughter.

The wedding, to which Alexander alludes in his letter below, was held on September 12 in the Protestant chapel in the Hôtel des Ambassadeurs de Hollande, 47 rue Vieille-du-Temple in Paris. The chapel’s records show that one of Franklin’s relatives was married there to a Scottish girl.5 The family reception seems to have taken place the following day at the Alexanders’ residence at St.-Germain. One of the guests, a visiting American who accompanied Franklin’s carriage, later recalled the journey from Passy. They traversed the Bois de Boulogne, passed by the Château de Madrid and Bagatelle, crossed the Seine via the beautiful stone Pont de Neuilly, rode through the magnificent grounds of Marly, and climbed the steep road to St.-Germain, with its commanding view of the countryside. When they reached the Alexander estate, they dined with a host of “distinguished guests,” including the mayor of Nantes.6

All we know about the ceremony itself is what Williams reported to his parents: that Franklin, having given his blessing, acted in the role of surrogate father.7 As to his bride, Williams admitted that since their first meeting, “Our History … has been on both Sides full of Changes in point of Situation,” but “our Affections have uniformly been the same, and we are now as happy a Couple as exists.” Indeed, he continued,

Were I to describe my Wife to you as appears to me, you would suppose the picture to be drawn by a young Lover. I will therefore only tell you what the World says of her, & in a few Words all who know her at all, know her to be Sensible, accomplished good natured prudent, and, what to me crowns all, the tenderest of Wives,—in short, nobody that ever saw her says anything but her Praises.

As a wedding gift, Franklin obliged the bride by presenting her with a miniature of himself. Painted by an unknown artist after Duplessis, the portrait is opaque water color on ivory. On the back of the miniature was affixed a small oval, in which were placed intertwining locks of the bride and groom’s hair.8

The newlyweds remained at St.-Germain until mid-October, but Williams’ honeymoon lasted only a day. On September 13, he was already submitting bills to his great-uncle and conducting business for his father-in-law.9