childbirth every day of the year. The mortality was one death to 171 births registered.

We entirely concur in Mr. Farr's remarks on the serious advantages which must result from the establishment of schools for the education of nurses and midwives in the metropolis and large towns. By such means a highly useful profession would be thrown open to women; and the utility to the community of a recognised body of respectable women, educated as nurses, acquainted with the plain doctrines laid down in the popular medical works on health, and possessing as much knowledge of midwifery as the French sage-femme, would be incalculable. Some of these schools, he thinks, might be connected with the present hospitals and lying-in institutions; others might be founded for the delivery of easy popular lectures, and for providing the wives of the indigent with gratuitous attendance, or attendance slightly remunerated-to be supplied by the young nurses, superintended by those practically versed in their art, and by medical officers. In a year or two years, intelligent women would acquire, at such an institution, sufficient information and skill to be useful nurses. He thinks it questionable, however, whether they should be taught the properties of drugs. He thinks it would be quite enough if they were taught in what circumstances to give a few drops of laudanum after delivery, and when to administer castor oil, or tincture of rhubarb, themselves, or in what way to apply the remedies prescribed by physicians or surgeons. To do more, would be to establish a new class of half-educated practitioners, like the druggists, and would infallibly lead to mischief, without any chance or prospect of countervailing good. The suggestions thrown out by Mr. Farr, in this part of his paper, are truly valuable, and well deserving the attentive consideration of the community at large. After having consulted several medical men in extensive practice, he states, that the want of good educated, trustworthy nurses, is felt in the highest circles, as well as in the middle ranks of society. He conceives that an institution for the education of nurses would probably succeed better than many of the medical schools; but they would be nurses for the middle and higher classes; the small outlay of capital which an education of the kind would involve, must tend very much to preclude the admission of midwives for the poor labourer's or the artizan's wife. For the many collateral advantages that would result to society from the possession of well-educated nurses we must refer to the original paper.

The next most important subject discussed in Mr. Farr's paper, is the Causes of the High Mortality in the Town Districts.

The population, in 1841, of the districts in the counties of Essex, Norfolk (except Norwich), Suffolk, &c. &c. an area of about 9,352 square miles, was 1,700,484. The deaths registered in the 4 years (1838-41) were 132,116.

The population of Birmingham, Aston, Bristol, Clifton, and several other towns, standing on 666 square miles, was 1,883,693, and the deaths registered in the 4 years were 205,966. The population of the town was greater than that of the country districts by 183,209; as a correction for this excess strike off 20,000 from the deaths in the former districts, and the excess of the deaths in the town districts will be found to be 53,850.

For another comparison the Metropolis, inhabited in 1841 by 1,875,493 persons, was compared with the South Western Division, comprising in Wiltshire, Dorsetshire, Devonshire, Cornwall, Somersetshire, a population of 1,740,017. The deaths were 189,927 in the Metropolis, 130,298 in the South Western Division, and after the same kind of correction as above, the result is of the same character.

The essential character, by which Mr. Farr was guided in classifying districts under the head of "town" or " country," is the density of the population, which can be expressed numerically by the "population to a given area," or the " area to each person." After having obtained from an immense number of facts the undeniable result, that certain diseases are much more fatal, and that the mortality is much greater, in towns than in the open country, Mr. Farr proceeds to enquire into the causes of the diseases, which the registration has proved to be so much more fatal in the town than in the country districts. To distinguish those causes, and to determine precisely the share which they have, single or combined, in the production of disease, it becomes necessary to institute an elaborate series of observations and experiments, in which the resources of chemistry, natural philosophy, medicine, and the mathematical sciences, must be called into requisition. Our present information does something more than prove the necessity of further inquiry; it enables us to trace the disease of towns to groups of causes, and to analyze them partially. And first with respect to the necessaries of life, a deficiency of which may stand as one of the causes of diseases in towns; these being the produce of labour, and of variable value, a portion of every population, savage or civilized, is unable to procure them, and is subject to privation in different degrees. These necessaries are, 1, Drink; 2, Food (animal and vegetable); 3, Physic; 4, Clothing; 5, Firing; 6, Lodging; 7, Cleansing. The relative value of these articles is represented by their price, which varies at different times and places; this price, however, it is evident, does not express the relative facility of procuring them; such facility being expressed by the ratio of the earnings of a family to the cost of its subsistence. Now when in any case this ratio is one of equality, there is what may be called a competency. This may be expressed by the value of the above-mentioned ratio. Let us suppose that a sufficient supply of necessaries can be procured by a family for £100. per annum; what would be the effect of reducing the earnings to £50. Experience proves to us, that the duration of life is not diminished in that ratio, for this reason, that by substituting a cheaper food the body may be sufficiently nourished. A low standard of subsistence, however, might be fixed on, any fall below which would be accompanied by a certain reduction of the mean life of the people. The ratio may be conceived under this simple form

Income

Drink+food + physic+ clothing + firing + lodging + cleansing,

= r;

and putting N for income (in money), C for the aggregate cost (in money) of the seven necessaries, and L for the mean physiological duration of life, the equation is L=L'; L' being the mean life in the particular cir

cumstances.

Suppose the cost of a full supply of subsistence for a labourer in the country to be £50. a year, and that the income of his family is £50. and that he is in such favourable circumstances altogether that he attains the natural mean term of life, the equation will be L=L. But let the income be reduced to £40, and if the ratio be simple the equation will be 40L= L. So that, if the mean natural life = 56 years, it would be reduced to 456, or 45 years, which is the present mean life in the best country districts. So that, by having several series of observations on the incomes of the labouring population in town and country, in different circumstances, together with the cost of the necessaries of life, we might determine the effect on the mean life of the people. It is hoped that such observations will be made. There are circumstances, however, which must prevent us from admitting that the command over the necessaries of life is in favour of the country population.

Another class of causes which may be supposed to affect the mean duration of life consists of atmospheric impurities, organic matter undergoing decomposition, and the contagious principles of zymotic diseases. The most minute investigation has established the fact, that the excessive mortality in towns is scarcely in any degree to be ascribed to the accumulation of carbonic acid gas, or any other gases, so complete is the provision made for their dispersion. The next consideration is, whether it is to matters suspended in the atmosphere of cities that the excessive mortality must be referred. Smoke is heated gas, carrying with it unburnt particles in suspension; the carbonic acid is scattered immediately by its diffusive velocity, and the particles of solid matter, carried up by the heated air into the sky, disperse, become invisible, and fall around insensibly, in a clear atmosphere, or at a distance when there is any wind. That the smoke is irritating to the air-passages, injurious to the health, and one of the causes of death, to which the inhabitants of towns are more exposed than the inhabitants of the country, is exceedingly probable; but, if the effect were very considerable, it would be most evident in the dense fogs, when the atmosphere is loaded with smoke, and breathed for several consecutive hours by the population-men, women, and children. Now no connexion has ever been observed between the increase of the mortality and the London fogs. The diseases, again, caused by smoke, must be of a mechanical nature, and affect the lungs and air-passages; it may increase the pulmonary diseases, but will assuredly not produce scarlatina, measles, typhus, and other diseases which prevail in towns. There is still another class of agents. Suppose in a school-room there are 100 children: a child is introduced for a few hours, in a state of scarlatina. The children have not had the disease before; 10 of them are affected. If 10 children with scarlatina were introduced, and the room were ill-ventilated, 30 or 40 of the children might be affected. The same may be said of other contagious diseases, as small-pox, measles, hooping-cough, dysentery, &c. &c. The numbers attacked by an infectious disease depend upon-1st. the susceptibility of the persons exposed; 2ndly, on the strength of the zymotic matter, which varies in the stages and forms of the several diseases; and 3rdly, on the density of the air in the room, and on the ventilation in it. If 100 healthy were placed in a room in immediate contact with 10

sick persons, if the room were small, the doors and windows closed, the greatest number possible would be infected; and if they went through the disease in the same circumstances, the mortality would also be the greatest possible. Thus, in consequence of the various public buildings in which crowds of persons assemble not being provided with the proper mechanical means of ventilation, and the air not being withdrawn, the very walls reek with the breathed atmosphere; and if any epidemic, such as influenza, be rife, several persons affected with the complaint are present, and great numbers are infected; the headache and oppression which come on are the first and often not the last symptoms. This is literally "taking poison;" though generally called "taking cold." It is a vulgar error to suppose that rooms are healthy when they are not hot; but the heat which is generated may increase the effect of the zymotic matter. Certain substances, then, taken from the bodies of the sick, produce, when introduced into other bodies, a series of specific phenomena, developed according to a determined type. Varioline, for instance, produces small-pox. These substances act as ferments.

The 267 feet of air passing through the lungs daily, if charged with these particles, will bring them into contact with the blood. With respect to the physical properties and chemical nature of these morbific particles, Professor Graham's hypothesis is, that they are highly organised particles of fixed matter, which may find its way into the atmosphere, notwithstanding, like the pollen of flowers, and remain for a time suspended in it; a condition which is consistent with the admitted difficulty of reaching and destroying those bodies by gaseous chlorine, and with the washing of walls and floors as an ordinary disinfecting practice.

It is certain that animal matter is exhaled from the lungs and cutaneous surface. The particles are small and rare, but inelastic, devoid of the diffusive force of gases and vapours. These particles, so held in suspension and inelastic, stagnate in air, and can only fall to the ground, or be carried away with the fluid in which they float. Smoke and organic matters are removed from a room in this way-by replacing all its gaseous contents. Every population throws off insensibly an atmosphere of organic matter, excessively rare in country and town, but less rare in dense than in open districts; and this atmosphere hangs over cities like a light cloud, slowly spreading-driven about-falling-dispersed by the winds-washed down by showers. This is matter which has lived, is now dead, has left the body, and is undergoing by oxidation decomposition into simpler than organic elements. The exhalations from sewers, churchyards, vaults, slaughter-houses, cess-pools, commingle in this atmosphere as polluted waters enter the Thames; and, notwithstanding the great provisions of Nature for the speedy oxidation of organic matter in water and air, accumulate, and the density of the poison (for in the transition of decay it is a poison) is sufficient to impress its destructive action on the livingto receive and impart the processes of zymotic principles-to connect by a subtle, sickly, deadly medium, the people agglomerated in narrow streets and courts, down which the wind does not blow, and on which the sun seldom shines. A small quantity only of organic matter can escape with the carbon and aqueous vapour from the skin and lungs (374 ounces daily, according to Dalton). Liebig, by operating on large masses of air, has

obtained ammonia, which is a product of the putrefaction of animal matter. So that the existence in the atmosphere of organic matter is incontestable ; and as it must be most dense in the densest districts, where it is produced in greatest quantities, and the facilities for its decomposition and removal are least, its effects-disease and death-will be most evident in towns. To this cause it is that Mr. Farr ascribes the mortality of towns, the people living in an atmosphere charged with decomposing matter, of vegetable and animal origin. He next proceeds to prove, not only that the mortality is greater in the town than in the country districts, but that the mortality of town districts has a certain relation to their density. The relation exists strictly between the density of the organic particles suspended in the atmosphere and the mortality; the density, however, of the matter in the air cannot be determined directly; and with the same number of persons on a square mile, the number of particles in the atmosphere will vary in different districts, according as the means of removing the refuse matter, by sewerage and other means, are more or less efficient. It is evident that, from the occupations of men in towns being mostly carried on in-doors, and in crowded workshops, while the agricultural labourer spends the greater part of the day in the open air, that the artisan indoors is not placed in the same favourable circumstances as the labourer; the sun and wind carry off the breath as soon as it is formed, while in the workshops of towns the men are shut in from the sun, and no streams of air carry off the steaming breath and perspiration; hence the mortality of working men in the Metropolis is much greater than the mortality of women at the corresponding ages-no such great discrepancy existing in the country districts. Thus, in estimating the effects of density of population in districts, Mr. Farr takes examples from the observations on females, in order to simplify the enquiry. The Metropolis presents the most favourable opportunity for investigating the influence of density; it is an aggregate of masses of people in districts larger, more homogeneous, and more on an equality in respect to subsistence, than could be found elsewhere; the difference between district and district is very great; but yet districts may be selected resembling each other on an average in all other points, save density.

For the purpose of comparison, he selects three of the statistical districts of the metropolis in which the mortality is highest-Whitechapel, Shoreditch, and Bethnal Green. These resemble each other in a great many particulars; but the density is different, and the mortality is greatest in the densest districts.

The mortality here taken was for the four years 1838-41.