M. Monge took the trouble to come to me one day, at the Observatory, to ask me to succeed him. I declined this honour, because of a proposed journey which I was going to make into Central Asia with M. de Humboldt. "You will certainly not set off for some months to come," said the illustrious geometer; "you could, therefore, take my place temporarily." "Your proposal," I replied, "flatters me infinitely; but I do not know whether I ought to accept it. I have never read your great work on partial differential equations; I do not, therefore, feel certain that I should be competent to give lessons to the pupils of the Polytechnic School on such a difficult theory." "Try," said he, "and you will find that that theory is clearer than it is generally supposed to be." Accordingly, I did try; and M. Monge's opinion appeared to me to be well founded. The public could not comprehend, at that time, how it was that the benevolent M. Monge obstinately refused to confide the delivery of his course to M. Binet, (a private teacher under him,) whose zeal was well known. It is this motive which I am going to reveal. There was then in the "Bois de Boulogne" a residence named the _Grey House_, where there assembled round M. Coessin, the high-priest of a new religion, a number of adepts, such as Lesueur, the musician, Colin, private teacher of chemistry at the school, M. Binet, &c. A report from the prefect of police had signified to the Emperor that the frequenters of the Grey House were connected with the Society of Jesuits. The Emperor was uneasy and irritated at this. "Well," said he to M. Monge, "there are your dear pupils become disciples of Loyola!" And on Monge's denial, "You deny it," answered the Emperor; "well, then, know that the private teacher of your course is in that clique." Every one can understand that after such a remark, Monge could not consent to being succeeded by M. Binet.