He remarked that these improved dwellings "afford accommodation to a population per acre as dense as, and in most cases even denser than, that afforded by the buildings which they replaced. Within limits it is not the density of population which regulates the health. But if a dense population is spread over the surface or close to the surface of the ground, by which means all movement of air is prevented, and if there are numerous corners in which refuse is accumulated, it will be difficult to prevent disease. Dr. Angus Smith's experiments show that while there is less oxygen and more carbonic acid in the eastern and in the more crowded parts of London, yet in open spaces the amount of oxygen rises and the carbonic acid diminishes very considerably; and that we are exposed to distinct currents of good air in the worst, and equally to currents of bad air in the best atmosphere, in towns like Manchester.

Dr. Tyndall showed that where there is quiescence in the air the tendency of his sterilized infusions to produce organisms was increased. The conclusion from all these experiments is to show the importance of laying out the general plan of dwellings in a town so that currents of air shall be able to flow on all sides with as little impediment as possible, by which means the air will be continually liable to renewal by purer air. The dwellings which have been constructed in the place of the very defective dwellings condemned by the medical officers of health in various parts of London specially illustrate the importance of this question of the circulation of air. These dwellings replace those in which the normal mortality was as much as 33, 44, and 50 per 1,000. But these improved dwellings provide ample space all round the blocks of building, so that air can flow round and through them in every direction, and so that there are no narrow courts and hidden corners for the accumulation of refuse. The mortality in the new dwellings is as low as 13 per 1,000 in some, and does not rise above 20 per 1,000 in any of them, and upon an average of years it may be taken at from 14 to 16 per 1,000. It is to this point that I specially desire to draw attention--namely, that these facts prove the possibility of bringing down the death-rate of the class of population which inhabits this sort of accommodation to rates varying from 15 to 16 per 1,000. I say of the class of population, because habits and mode of life have an important influence on health and on longevity.

Mr. Chadwick and Dr. Richardson obtained some statistics for Westminster, for the use of a committee of the Society of Arts, which indicate the very different conditions of health to which the different classes of population are subject. It appeared from these statistics that out of one hundred deaths of the first class, or gentry, six were those of children in their first year, and nine of children within their fifth year; while out of one hundred deaths of the wage classes twenty-two are those of children in their first year, and thirty-nine within their fifth year. If we take the average duration of life of all who have died of the first class, men, women, and children, we find that they have had an average of fifty-five years and eight months of life; while of the wage classes they have had a mean of only twenty-eight years and nine months. And if we take the average duration of life of those who have escaped the earlier ravages of death up to twenty years of age, the males who have died of the first class have had sixty-one years of life, while of the wage class the males have had only forty-seven years and seven months. Moreover, of the first class in Westminster, the proportion who have attained the old age, and died of natural causes, is 3.27 per cent., but of the wage classes only a fraction, or two-thirds per cent., did so. I have obtained similar returns for this town. It was considered desirable, for the purpose of this return, to divide the population into the following five classes: First, gentry and professional men; second, tradesmen and shopkeepers; third, shipwrights, chain and anchor smiths, iron forge laborers, etc., fourth, seamen, watermen, fishermen, etc.; fifth, other wage clashes and artisans; and each of these classes represents distinct sanitary conditions and habits of life. The healthiest class is that of the seamen, watermen, and fishermen. The mean age at death of all who died of that class, men, women, and children, is thirty-seven years, as compared with thirty five years for gentry and professional men; while the mean age of shipwrights, chain and anchor makers, and iron forge laborers is only twenty-two years. The President considered that these points gave much food for reflection. He then touched upon the important question of the effect of occupation upon health, and remarked: If we take the professional and merchant class, who attend at their offices during the daytime, we may be sure that, as a rule, they are placed in unhealthy surroundings during that time, and in many cases have to breathe during their hours of work as bad an atmosphere as that in which the wage classes work. He also quoted returns showing that the great mortality among the tradesmen class in Westminster was explained from the fact that the best rooms in the houses in which they live were let for lodgings, the tradesmen contenting themselves with living in the basements or back premises, which were frequently unhealthy. He looked for great improvements in the health of the wage classes by the construction of improved dwellings; but, he confessed, in many cases workmen required to be taught to attend to precautions devised for their health.

On the subject of sickness caused by insanitary conditions, he quoted the remark of an East London clergyman that the "poor go on living in wretched places, but have much ill-health." He showed from Mr. Burdett's figures that the London voluntary hospitals and dispensaries cost nearly £600,000 a year to administer--an expenditure incurred mainly for the purpose of "patching up" the wretched poor who had been injured by bad drainage, want of ventilation and the like; and he urged that it might be safely assumed preventive measures would bring down the death-rate of the wage class to one-half, reducing also the sickness rate in at least a similar proportion. By means of this item alone the wage-earning power of the industrious classes would be enlarged by some millions of pounds, and their comfort correspondingly increased. There would also, he contended, be other distinct economies, for there would be less need for much of the accommodation in prisons, reformatories, and workhouses now needed from evils incident to unhealthy circumstances and crowded dwellings.

He dwelt upon the economic advantages of sanitary measures generally, dealing first with the subject of the conversion of sewage into manure, and then, in relation to the provision of healthful dwellings, such as those of the Metropolitan Association for Improving the Dwellings of the Industrial Classes, he showed that the cost of such dwellings had been about £1,900,000 for 11,000 persons. By the saving in life and health, through the continuance in earning power of men, whose lives would otherwise have been cut short, he estimated that the expenditure of the £1,900,000 for the 11,000 persons, by the addition often years' earning power to the heads of families, brought in a return of £4,600,000, and urged these facts as showing the pecuniary advantages accruing to the nation from sanitary improvements which led to decreased death and sickness rates. On the one hand, he said, insanitary dwellings and insanitary conditions of life engendered sickness, entailed poverty, and fostered crime, while improved dwellings insured improved health, and by affording a security for the more continuous earning of wages created the possibility of a comfortable home. Advanced sanitarians had long preached these doctrines, and he was happy to think that they were at last beginning to hear some results, and in those results he saw the means of developing morality, contentment, and happiness among the people.

[NATURE.]