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such conditions and circumstances as influencing the death rate of cities and towns. They may be grouped in three general classes as follows:

1. Vatural Conditions. - Such as the conditions of climate (temperature, rainfall, humidity, prevailing winds), elevation above sea level, distance from sea, character of the soil (dryness or moisture).

2. Artificial Conditions. — Density of the population, purity of water supply, efficiency of sewerage system and sewage disposal, sufficiency and purity of food supply, and especially of milk, protection from accidents, management and prevention of infectious diseases, freedom of intercommunication, especially among children, efficiency of municipal sanitation.

3. Character of the Population. — Race and nationality, distribution by sexes and ages, occupation, education, social condition as to poverty or wealth, habits, size of families, etc.

Each of the foregoing conditions probably influences the length of human life in a greater or less degree.

In estimating the death rate of cities and towns presented in the first part of this paper, a distinction is maintained between death rate as calculated from the actual number of deaths registered in a given city or town for a definite period, and the true death rate of the resident or census population. For this reason, in estimating the death rates of cities and towns allowance has been made, where actual numbers were known, for the following circumstances : Deaths of non-resident invalids at summer resorts.

Deaths by shipwreck upon the coast and at sea, and by drowning at beaches (of non-residents). For example, there were 2,103 such deaths of Gloucester fishermen, and 37 at Hull and 10 at Nantucket, during the twenty-year period. There were also 229 deaths of non-residents, mostly invalids, at Cottage City, Hull and Nantucket in the same time. Deaths of non-residents at public institutions.

If it were possible to obtain the exact numbers, it would be proper to reduce the death rate of the larger cities and especially of Boston in consequence of two causes : 1. The deaths of non-residents in hospitals, asylums and charitable institutions, who have sought the cities for treatment. 2. The daily accession of a multitude of people from suburban districts, who are not included in the census of the

cities, but contribute to a certain extent to the death rate. (The ratio of fatal accidents reported in Suffolk County in 1890, as compared with the resident population of that census year, was 5.8 per 10,000, while that of the State at large was only 3.8 per 10,000.)

The fallacy of drawing conclusions from small numbers of people and from short periods of time must - be acknowledged as a statistical axiom ; and hence the general conclusions of this paper have been drawn, as far as possible, from groupings of towns and cities extending over a period of twenty years.

MEASLES. - In the section upon measles, the inquiry shows that the course of the disease was very variable from year to year, the mortality rate of 1872 from this cause being nearly thirty times as great as that of the minimum year of mortality from the same cause (1879).

Density of population appears to have furnished a favorable condition for its spread.

Geographical position does not appear to have had a marked influence upon the mortality rate from this disease, except in so far as towns were near to or remote from large and densely settled centres of population, and in free communication with them.

SCARLET-FEVER. — This disease prevailed during the period with greater regularity and with a greater mortality rate than measles. The extreme of its high mortality (in 1875) was about twelvefold greater than that of the minimum year (1889).

Density of population appears to have favored its spread. As in the case of measles, the mortality rate from this cause was least in small, sparsely settled towns, with poor facilities for intercommunication with large cities.

The difference in mortality rate from this cause of the two large manufacturing cities (Lowell and Fall River), with similar populations, is worthy of note, Lowell being below the average of the State and Fall River far above it.

Geographical position does not appear to exert a marked influence on the prevalence of this disease.

DIPHTHERIA AND Croup. — The extremes of mortality in different years have not been so great as in the case of measles and scarlet-fever; that of the highest year (1876) was 19.9 per 10,000, and that of the lowest (1873) was 4.7.

Density of population appears to have afforded a favorable condition for its spread.

Geographical distribution does not appear to have been a prominent factor, except in the fact that a small north-west portion of the State, which is all at a high elevation above the sea, appears to have suffered most severely.

SMALL-Pox. — During all of the years of the period under consideration, except the first three, the State was comparatively exempt from this scourge. The extremes of mortality were 0 in 1886 and 6.7 per 10,000 in 1872.

The conditions which appear to have influenced the mortality from small-pox in Massachusetts are: density of population, nearness to or remoteness from large centres of population, the use of rags in the manufacture of paper, and the thoroughness with which vaccination and revaccination have been performed. Aside from these conditions, geographical position does not appear to have had material effect upon its prevalence.

As a common factor favorable to the spread of each one of the foregoing diseases (measles, scarlet-fever, diphtheria and small-pox), independent of density of population, location upon one of the principal railway lines of communication appears to have had a marked influence.

TYPHOID FEVER. — The mortality from typhoid fever was less variable in its fluctuations than that of either of the diseases before mentioned, the extremes being 3.7 per 10,000 in 1879 and 1890, and 11.1 in 1872. In general, there was a decided decrease, comparing the two decades, from 6.2 in the former to 4.5 in the latter.

Density either does not appear to have had a controlling influence upon the mortality from typhoid fever, or its effect is counterbalanced by the presence of good public water supplies. In cities having a comparatively dense population and a generally polluted water supply, the mortality rate was high.

The greater number of towns lying in certain river valleys had unusually high ratios of typhoid mortality. This applies to the Connecticut and the Chicopee. In the case of the former river it has no apparent relation to the public water supply in the majority of the towns lying within ten miles of its eastern bank, since most of these towns have no public water supply. In the case of the lower portion of the Chicopee, every town had a high mortality from this cause, beginning with Ware, which had the highest of any town in the State except Dalton; and further down the stream, Palmer, Belchertown, Ludlow, Wilbraham, Monson, Chicopee and Springfield, all had unusually high typhoid mortality. The high mortality of the two principal cities in the lower Merrimack valley has already been made the subject of a paper by H. F. Mills, C.E., in the last annual report of the Board, in which it was shown that a polluted water supply was the undoubted cause of the excessively high mortality rate. The greater part of Essex County, lying south of the Merrimack River, was unusually free from the disease, and so also was the entire suburban metropolitan district adjoining Boston.

CHOLERA INFANTUM. — The extremes of mortality from this cause were 21.7 per 10,000 in 1872, and 7.9 per 10,000 in 1879.

Density of population has a marked effect in increasing the mortality from this disease.

The quality of the milk supply appears to have a definite relation to the mortality from cholera infantum.

The employment of married women in industrial operations away from their homes also co-exists with high mortality from cholera infantum.

CONSUMPTION. — Consumption has presented a more uniform mortality rate from year to year than any other disease; the extremes were 36.2 per 10,000 in 1872, and 25.7 in 1889. average for the twenty years was 30.8. There was a gradual decrease from the beginning to the end of the period, the first decade having a mortality rate of 32.7, and the second of 29 2.

The extremes of mortality were in Berkshire and Franklin, which had low death rates from this cause; and Nantucket and Suffolk, which had high rates.

Density appears to have affected the mortality rate from consumption, in the ratio of 1,000 deaths for dense, 810 for medium and 727 for sparse districts.

Geographical position also exercises a marked controlling effect in proportion to the distance of the districts from the sea-coast, the mortality rate decreasing from the sea-coast counties toward Berkshire, at the western extremity of the State. The altitude of the region also generally increases westward or inland.

The

PNEUMONIA. — The mortality rate from pneumonia was also comparatively uniform during the twenty-year period, the extremes being 12.4 per 10,000 in 1871, and 18.2 in 1888. There was an increase from 14.6 per 10,000 in the first ten years to 16.6 in the second ten years.

The effect of density upon the mortality from this disease does not appear to have been so decided as in the case of other well-known infectious diseases, the ratio being as 15.6 per 10,000 for the densely settled towns, and 14.1 for the sparsely settled.

Geographical position, with reference to distance from the sea-coast, appears to have had a marked coincidence with the mortality rate, the inland counties presenting a high mortality rate and the sea-coast counties a low one. Elevation above the sea also appears to have coincided with a high mortality from this cause.

With reference to these two conditions, distance from the sea-coast and elevation above sea level, consumption and pneumonia appear to be to a considerable degree complementary.

In connection with the foregoing summary the following condensed statistics are presented, which have reference to the relation of sex, age and season of the year to the diseases under consideration. They will be found useful in making a more complete study of the subject.

In the table which relates to the mortality by months (page 873) the percentages have been reduced to uniform periods of one-twelfth of a year, in order the better to show the actual incidence of the disease at each such period.

In a very small number of cases the sex was unknown. The numbers were quite small, and are therefore disregarded in the foregoing tables.

The following figures give the mortality by sex, the deaths of each sex from the given disease being compared with the persons living of each ses, and in the case of diseases peculiar to children the comparison is made with the persons living of each sex of ages from 0 to 10, and in the case of cholera infantum from 0 to 5.

In the first table on the following page the only diseases in which the difference in the mortality of the sexes is excessive and worthy of special notice are small-pox and phthisis. For every 1,000 males who died of small-pox there were 662 deaths of females. It is worthy of note, however, that the mortality of the sexes at different ages presented a wide variation. While the mortality of the two sexes for the period of life 0-20 years was exactly equal, or 50 per cent. of each, that of the remainder of life was 70.5 per cent. for males and 29.5 per cent. for females. It would appear that this remarkable result is due to the much greater exposure of males to infection in adult life, while that of children is practically equal; and not even the fact of a greater exposure of female operatives in the paper-making industry is sufficient to counterbalance the still greater exposure of males in other densely settled communities.

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