One morning John Herschel and I called on Laplace who spoke to us of various English works on mathematical subjects. Amongst others, he mentioned with approbation, "Un ouvrage de vous deux." We were both quite at a loss to know to what work he referred. Herschel and I had not written any joint work, although we had together translated the work of Lacroix. The volume of the "Memoirs of the Analytical Society" though really our joint production, was not known to be such, and it was also clear that Laplace did not refer to that work. Perceiving that we did not recognise the name of the author to whom he referred, Laplace varied the pronunciation by calling him vous deux; the first word being pronounced as the French word "vous" and the second as the English word "deuce." Upon further explanation, it turned out that Laplace meant to speak of a work published by Woodhouse, whose name is in the pronunciation of the French so very like vous deux.
Fourier, then Secretary of the Institute, had accompanied the first Napoleon in his expedition to Egypt. His profound acquaintance with analysis remains recorded in his works. His unaffected and genial manner, the vast extent of his acquirements, and his admirable taste conspicuous even in the apartments he inhabited, were most felt by those who were honoured by his friendship.
With M Biot I became acquainted in early life: he was then surrounded by a happy family. In my occasional visits to Paris I never omitted an opportunity of paying my respects to him: when deprived of those supports and advanced in life, he still earnestly occupied himself in carrying out the investigations of his earlier years.
At a later period I took with me to Paris the complete drawings of Difference Engine No 2. As soon as I had hung them up round my own apartments to explain them to my friends I went to the College de France, where M Biot resided. I mentioned to him the fact, and said that if it was a subject in which he was interested, and had leisure to look at these drawings, I should have great pleasure in bringing them to him, and giving him any explanation that he might desire. I told him, however, that I was fully aware how much the time of every man who really adds to science must be occupied, and that I made this proposal rather to satisfy my own mind that I had not neglected one of my oldest friends than in the expectation that he had time for the examination of this new subject.
The answer of my friend was remarkable. After thanking me in the warmest terms for this mark of friendship, he explained to me that the effect of age upon his own mind was to render the pursuit of any new inquiry a matter of slow and painful effort; but that in following out the studies of his youth he was not so much impeded. He added that in those subjects he could still study with satisfaction, and even make advances in them, assisted in the working out of his views experimentally by the aid of his younger friends.
I was much gratified by this unreserved expression of the state of the case, and I am sure those younger men who so kindly assisted the aged philosopher will be glad to know that their assistance was duly appreciated.
The last time during M Biot's life that I visited Paris I went, as usual, to the College de France. I inquired of the servant who opened the door after the state of M Biot's health, which was admitted to be feeble. I then asked whether he was well enough to see an old friend. Biot himself had heard the latter part of this conversation. Coming into the passage he seized my hand and said "My dear friend I would see you even if I were dying."