THE following is the text of the address presented by Sir Arch. Geikie for the Royal Society at the recent celebration of the quatercentenary of the University of Aberdeen —The Royal Society of London for Promoting Natural Knowledge sends cordial greetings to the University of Aberdeen on the auspicious occasion of the celebration of the four hundredth anniversary of its foundation. The Royal Society would more specially desire to record its sense of the importance of the services which the University has rendered to the progress of science. From its infancy the society has been privileged to count among its fellows distinguished professors and graduates of Aberdeen, and this close and valuable association still continues. It is a gratification to recall that the illustrious family of the Gregorys, which for some two centuries shed so much fame upon the University and upon Scotland, were from the beginning intimately linked with the Royal Society. James Gregory early reached such eminence in mathematical and astronomical research that in 1668, when he was only thirty years of age, he was elected a fellow, six years after the incorporation of the society. His invention of a reflecting telescope, of which he had first conceived the idea, prompted Newton to proceed in a similar direction in order to evade the difficulties of chromatic dispersion, and led to mutual regard and friendly cooperation. To his brother David Gregory, who had the distinction of being one of the earliest effective promoters of the Newtonian philosophy, the society is also indebted for important communications published in early volumes of the Philosophical Transactions. The obligations of physical science to Aberdeen did not end with the lives of the masters of the seventeenth century, for within living memory the University has numbered among its professors the world-renowned pathfinder James Clerk Maxwell. To the progress of the study of medicine the same remarkable family of Gregory continued during successive generations to make important contributions, while the fame of the medical school was in more recent years extended by Allen Thomson. In natural science the well-remembered names of John Fleming, William MacGillivray, and James Nicol appear among those who have sustained the scientific reputation of Aberdeen. But it is not only with the scientific side of culture in the University that the Royal Society has had interesting links. It is a pleasure to remember that Thomas Reid, the father of Scottish philosophy, whose fame is one of the fairest pearls in the chaplet of the northern University, contributed to the Royal Society in 1748 an essay upon quantity. In remembrance of these varied associations of the past, and with sincere wishes for their continuance in the future, the Royal Society gladly adds its felicitations to those which will this year come from all civilised countries to the University of Aberdeen.