The President commenced his inaugural address by thanking, in the name of the Sanitary Institute of Great Britain, the Mayor and Corporation of Newcastle for the invitation to visit this important industrial metropolis of Northern England. The invitation, he said, was the more satisfactory because Newcastle was advancing in the van of sanitary improvement, and was thus proving the interest of this great city in a subject which was contributing largely to the moral and material progress of the nation. Of all the definite questions which were made the subject of the instruction by congresses at the present time, there was scarcely one which deserved a greater share of attention than that which called that congress together--namely, the subject of the public health. Within the last half century the whole community had been gradually awakening to the importance of a knowledge of the laws of health, and the energies of some of the ablest intellects in the world had been employed in investigating the causes of disease, and in endeavoring to solve the problem of the prevention of disease. There was much that was still obscure in this very intricate problem, but the new light which was daily being thrown upon the causes of disease by the careful and exact researches of the chemist and physiologist was gradually tending to explain those causes and to raise the science of hygiene, or science of prevention of disease, out of the region of speculation, and enable it to take rank as one of the exact sciences. Long ago the careful observation of facts had shown that the preservation of health required certain conditions to be observed in and around dwellings, conditions which, when neglected, had led to the outbreaks of epidemic disease from the days of Moses to the present time. But while the results had been patent, it was only in recent years that a clew had been obtained to the occult conditions in air and water to enable their comparative healthful purity to be distinguished. The researches of Pasteur in respect to the forms of disease in French vineyards opened a fruitful field of inquiry, and the theories of Dr. Bastian on spontaneous generation gave rise to the beautiful series of experiments by Tyndall on bacterian life. A large band of leading scientific men, both in this country and over the whole world, were devoting their energies to a knowledge of the recent theories on the propagation of disease by germs. In a lecture on fermentation, Tyndall remarked that the researches, by means of which science has recently elucidated the causes of fermentation, have raised the art of brewing from being an art founded on empirical observation--that is to say, on the observation of facts apart from the principles which explain them--into what may be termed an exact science.