Finding (or Not) An Educator for a Prince—On the Recent Discovery of a Missing Letter from Leonhard Euler

The discovery of a missing letter from Swiss mathematician Leonhard Euler is discussed. Most surviving correspondence of Euler, along with his scientific papers and notebooks, is today housed in the archives of the Russian Academy of Sciences in St Petersburg with smaller collections around the world in Basel, Berlin, and elsewhere. Only very rarely do his letters come up for sale at one of the great or perhaps less well-known auction houses, or simply turn up through serendipitous searching, as was the case with a letter he wrote on some questions in hydrostatics to the French mathematician and natural philosopher, Jean le Rond d'Alembert. It was, therefore, a matter of considerable interest that recently a letter sent by Euler to Johann Daniel Schumacher (1690-1761), head of administration at the St Petersburg Academy of Sciences, came onto the antiquarian market in Germany.