The report of the Metropolitan Board of Health for the past year has just been published in a large volume of 635 pages, which contains a vast amount of valuable information relating to the sanitary government of the Metropolitan District.

The vital statistics therein presented were published in the TIMES several weeks ago from advance shoots of the report; but there is one feature of the document which has not yet been made public, and that is a special record of the Sanitary condition of the tenement-houses of the City, which was carefully prepared by Mr. Norris R. Norton, a competent and well-informed clerk in the Bureau of Vital Statistics. In detailing the condition of those houses, Mr. Norton divided the City into three districts. The First District comprises the First, Second, Third, Fourth, Fifth, Sixth, Eighth, Ninth, Fourteenth and Fifteenth Wards: the Second District, the Seventh, Tenth, Eleventh, Thirteenth and Seventeenth Wards, and the Third District the Twelfth, Sixteenth, Eighteenth, Nineteenth, Twentieth, Twenty-first and Twenty-second Wards. The results of his observations as given in the report are substantially as follows:

The First District

The lower portion of the First District is almost wholly given up to the commerce of the City. It is filthy in the last degree, and is peopled by a class that is exceedingly improvident, consisting mainly of newly-arrived immigrants, and those who make their living about the docks and piers and by the water side. It is, in some respects, the worst district in the City, containing numerous lodging-houses, dance-houses, drinking-dens and brothels, which serve not only to perpetuate the degradation upon which they subsist, but also to swell the mortality record to a degree that would be frightful, if its causes were not understood. The upper and western porti0n of the district is in much better condition than the lower one, although there are many unwholesome spots upon its surface. Cart men and teamsters are, chiefly, its occupants, and they are a thrifty, economical and industrious class of people. The numerous stables in which their horses are kept are the source of considerable discomfort, however, and much of the mortality of the district is due to the deleterious gases there generated and scattered through the atmosphere. The entire district contains five public markets, six first-class, and several very low hotels, more than two-thirds of the drinking dens and brothels, with a large majority of the gamblers and thieves of the City. According to a recent census it embraces 3,965 tenement houses and 187,280 inhabitants. It is not only the commercial centre of the metropolis, but it is also the centre of its vice and crime.

The Five Points of New York, whose former depravity has passed into the annals of history, still remain, in spite of mission efforts, although their condition has been materially improved within the past few years. Little was accomplished toward the reform of the Fourth Ward brothels and rat pits, by the efforts of religious men, and they, too, still remain as a dark blot upon that portion of the City. From Canal-street to Fourteenth-street Broadway is flanked, throughout almost its entire length, two blocks deep, by brothels, which, day by day and night after night, disseminate an infection that imperils the health and lives of all classes of people to an extent that can scarcely be measured. Two reformatory institutions are located within the district, "The Home for the Fallen" and "The Midnight Mission," and both are doing much, in a quiet and unobtrusive way, to elevate the moral and social status of the population. The tenement-houses of the district suffer greatly from defective sewerage, cleansing, scavenging and subsoil drainage, and almost uniformly from a lack of care of sufficient ventilation. Nearly sixty-three per cent, of the whole number of these dwellings are in a condition detrimental to health and dangerous to life.

The Second District

This sub-division of the City is situated east of Catharine-street, the Bowery and Fourth-avenue, and south of Fourteenth-street. It is the most densely populated part of the City, the Seventeenth Ward, which comprises less than one-fortieth of the total area of the City, alone, containing not less than one-tenth of the whole population. A census of that ward, taken recently by the Police, showed that 4,120 houses contained 95,091 inhabitants, of whom 14,016 were children under five years of age. The Eleventh Ward is still more densely populated, the rate being not less than 200,000 to the square mile, and giving scarcely sixteen square yards to each person.

The Seventh, Tenth and Thirteenth Wards are also very much crowded, the average number of square yards to each person being about twenty. The house accommodations are thoroughly inadequate. The population is mainly foreign born, the Germans being largely in the majority. It is composed for the most part of those industrial classes who depend upon the various trades for a livelihood, including a large colony of rag-pickers. They are vastly superior to the people of the First District, in that they are self-supporting and less vicious. They need hospitals more than prisons, and they tax the public charities more through their misfortunes than their crimes. The sanitary wants of the people are principally domestic and domiciliary: wants that may readily be met by a remedy of the merely architectural mistakes that prevail to a great extent in the dwellings of the humbler classes. The total population of the five wards comprising the district in 1865, was 233,403, but these figures have since been largely increased. The mortality in its tenement-houses during nine months of the year 1868 was eighty-three per cent. of the whole, which is a striking fact.

The Third District

The third and last group of wards set apart for examination in regard to the housing of the poor, in its relation to the public health, embraces all that portion of the Island that lies north of Fourteenth-street. The insufficient sub-soil drainage of Murray Hill; the saturated soil of the eastern margin of the Eighteenth and Twenty-first Wards; the rapid transition of the Nineteenth and Twenty-second Wards from rocky ridges and tortuous water courses to paved thoroughfares and densely peopled squares; the unhealthy lowland known as Harlem Flats, and the sanitary benefits bestowed upon the district by the health-giving Central Park are so familiar that repetition is needless. Nevertheless, these circumstances must be borne in mind as a very important element in the problem which the Board of Health is called upon to solve. They lie at the very foundation of the study of preventable causes of sickness and death, and require the best efforts of the Sanitary inspector, together with the most consummate skill of the Sanitary Engineer.

From the social stand-point every grade and class of society, the virtuous and the vicious, the bone-picker and the banker, the mendicant and the millionaire, may be found in this district, in some places removed from each other less than the distance across a single block. It is the most fashionable part of the Metropolis, and contains a large proportion of its wealth, culture and refinement, and yet some of the finest residences overlook the filthiest shanties to be found within the City limits.

The ground area in many places is fearfully overcrowded. Front and rear buildings encumber the surface of the lots fronting nearly every street. The rows in the rear are almost invariably built back to back, and very frequently with no intermediate space whatever. These houses, similar in structure, from cellar to roof, are made to accommodate from two to six families on each floor, and the number of floors is left entirely to the option of the owner. Through and through ventilation, especially in the rear houses, is an utter impossibility. It is a fact that the darkness of these houses of the Second and Third Districts afford many circumstances which conspire to perpetuate that vice which in the First District walks freely abroad amid the glare of open day. "Clearly, it would be far wiser," so reasons the report, "to make such an effort as will prevent the yielding ranks of vice from being newly recruited, than to attempt to reform those persons who are already its victims. And for such labor there is no field that promises so rapid and so large a harvest as the overcrowded tenement-houses of the eastern and northern portions of the City. The tenements of the lower wards will soon give place to the demands of trade. Those north of Fourteenth-street will, consequently, become more crowded and more vicious, and to ignore the social results which must of necessity follow, will be fatal, not only tot he health, but also to the best interests of the community, already overtaxed in the effort to pay for its vice."

The tenement-houses of the Third District, from a sanitary point of view, present examples of the very best and the very worst of their class. They furnish homes for a very large number of the laborers and mechanics of the City, as well as for the vast majority of those who, although having more lucrative occupations, are compelled by the high price of rents and room articles to accept a condition which, however distasteful, can scarcely be avoided. The large tenement buildings of this district number 6,955, and the population of the district is about 310,000. The death records of this district, with those of the others, show conclusively the fatal influences working upon the tenement house population, and the comparative immunity from death of those who dwell in private houses.

In the present state of sanitary knowledge, it is impossible to doubt that much of this waste of life and health is altogether needless and preventable; and it is quite certain that whatever is needless depends upon certain local conditions which may be easily discovered and thoroughly understood, and whose control is entirely within the scope and province of the sanitary authorities.