The President gave a short historical sketch of the Society on the occasion of the commencement of its Hundredth Session. He said that, before the business commenced, he ought to call attention to a peculiarity of the present meeting, and to make one or two observations upon it. This was the hundredth session of the Royal Society. Most cordially did he congratulate the Society and its members on having arrived at that interesting period of its history. But it was right he should say that it would be a mistake to suppose that, although this was the hundredth session, they were absolutely centenarian. This was not the anniversary of the birth of the Royal Society. For some reason or other–he did not know how–the hundredth session began before the Society was absolutely a hundred years old. How it exactly came about he was not quite sure. The Royal Society's charter bore date March 1783; and he supposed, like other great institutions, they had a previous autumn session–and in that way, possibly, the difference was to be accounted for. But, in any view, it is a great occasion for meditation and observation, and there may come a time for such a word, but on the present occasion he had not the material sufficient to do anything like justice to a theme so large. Only in a few sentences would he go back to March 1783, and glance upon the long career which the Society had run. A long and distinguished course, he thought they might say, seeing it was to their distinguished predecessors. they owed its glory and its present flourishing existence. There had been many speculations as to where the Royal Society came from, and its feeders had been examined and searched for with great assiduity.