I came by twice yesterday to tell you that I received a letter from M. de Montalembert, in which he requested that I ask you, since he is not feeling well, to postpone until another day the pleasure that you were to going to give him by going to dine at his house today. Consider yourself informed, my dear doctor.—I am much obliged for what you told me. We have been in agreement on this subject for a long time, thinking that the experiments conducted during the periods of Aurores Boréales should be done with needles of various kinds of metals and other substances. Let me know, please, if you are available this afternoon. Until then, please accept a thousand sincere compliments. I hope that you will accept M. de Paulmy's proposition.