Thus, in January, 1882, the mean weekly temperature fell from 43.9° F. in the second week to 36.2° in the third, with fog and mist. The number of deaths registered in London during the third week, which may be taken as corresponding with the meteorological conditions of the second week, was 1,700, and in the next week 1,971. Unusual cold, with frequent fogs and little sunshine, continued for four weeks, the weekly number of deaths rising from 1,700 to 1,971, 2,023, 2,632, and 2,188. The deaths from acute diseases of the lungs in these weeks were respectively 279, 481, 566, 881, and 689, showing that a large proportion of the excessive mortality was caused by these diseases. At the end of November and in December of the same year there was a rapid fall of temperature, when the number of deaths from acute diseases of the lungs rose from 297 to 358, 350, 387, 541, 553, and 389 in the respective weeks. From November 29 to December 9 the sun was seen only on two days for 4½ hours, and from December 9 to the 18th also on two other days for less than 4 hours, making the total amount of sunshine 8.1 hours only in 20 days.

In January and February the excess of weekly mortality from all diseases reached the large number of 504 deaths; in December it was less, the fogs not having been so dense, but the excess equaled 246 deaths per week.

The relations between a high summer temperature and excessive mortality from diarrhoea have long been well known, but the immediate cause of the disease as an epidemic is not known. Summer diarrhoea prevails to a greater extent in certain localities, notably in Leicester (and has done so for years); and the cause has been carefully sought for, but has not been found out. Recent researches, however, point to a kind of bacillus as the immediate cause, as it has been found in the air of water-closets, in the traps under the pans, and in the discharges from infants and young children. In order to indicate more readily how intimately the mortality from diarrhoea depends on temperature, I now lay before you a table showing the mean temperature for ten weeks in summer, of seven cold and hot summers, the temperature of Thames water, and the death-rates of infants under one year per million population of London:

London

Deaths under 1 Year, in July, August, and part of September, from Diarrhoea per 1,000,000 Population Living at all Ages, arranged in the Order of Mortality.

As may be seen, the deaths of infants under 1 year of age from diarrhoea per 1,000,000 population was only 151; while the mean summer temperature was only 58.1° F. against 189 in 1862, when the mean temperature was 59.0°. In 1879, when the mean temperature was 58.7°, the deaths from diarrhoea rose to 228 per million, but a few days were unusually hot. In 1877 the mean temperature of the air was 61.2°, of the Thames water 63.3°, and the mortality of infants from diarrhoea 347 per million population. In 1874, when the mean temperature of the air was 61.7°, the mortality rose to 447 per million; and in the hot summers of 1878 and 1876, when the mean air temperatures were 64.1° and 64.9° respectively, the death-rates of infants were 576 and 642 per million population. The relations, therefore, between a high summer temperature and the mortality from diarrhoea in infants are very intimate. I have selected the mortality among infants in preference to that at all ages, as the deaths occur more quickly, and because young children suffer in greater proportion than other persons.

The proportionate number of deaths at all ages from diarrhoea corresponds pretty closely with those of infants. To prove this, I made calculations for three years, and ascertained that only 3.9 per cent. of all the deaths from this disease were registered in the weeks having a temperature of less than 50°; 11.9 per cent. in the weeks having a temperature between 50° and 60°; while in the comparatively few weeks in which the temperature exceeded 60° F., as many as 84.2 per cent. of the total number of deaths was registered. In the sixteen years, 1840-56, for which many years ago I made a special inquiry, only 18.9 per cent. of all the deaths from diarrhoea occurred in winter and spring, against 81.1 per cent. in summer and autumn. In the twenty years, 1860-79, there were seven years in which the summer temperature was in defect when the mortality per 100,000 inhabitants of London was 200; while in ten summers, during which the temperature was in excess by 2° or less, the mortality was 317 per 100,000. The mean temperature was largely in excess, that is to say, more than 2° plus in three of these summers, when the mortality reached 339 per 100,000 inhabitants.

These figures show that great care should be taken in hot weather to prevent diarrhoea, especially among young children; by frequent washing with soap and water to insure cleanliness, and proper action of the skin; by great attention to the food, especially of infants fed from the bottle; free ventilation of living rooms, and especially of bedrooms; and by protection, as far as possible, being afforded from a hot sun, as well as by avoiding excessive exercise. All animal and vegetable matter should be removed from the vicinity of dwelling-houses as quickly as possible (indeed, these should be burnt instead of being put in the dust-bin), the drains should be frequently disinfected and well flushed out, especially when the mean daily temperature of the air is above 60° F.

Time will not admit of more than a mere mention of the relations between meteorological phenomena and the mortality from many other diseases and affections, such as apoplexy from heat, sunstroke, liver diseases, yellow fever, cholera, whooping-cough, measles, etc., especially as the state of our knowledge on the subject is so very limited. A comparison between the mortality from several diseases in this and other countries shows that certain of these do not prevail under closely corresponding conditions. Thus the curves of mortality from whooping-cough, typhoid fever, and scarlet fever do not correspond with the curves of temperature in both London and New York, and the same may be said of diarrhoea in India. It is therefore evident that some other cause or causes than a varying temperature must be concerned in the production of an increased death-rate from these diseases. The subject is of great importance, and I do not despair of our obtaining some day a knowledge of the agents through which meteorological phenomena act in the production of increased and decreased death rates from certain diseases, and the means by which, to a certain extent, these injurious effects on man may be presented.

P. Rosenbach has found experimentally that potassium bromide diminishes the sensibility of the cortical substance of the cerebrum to electric excitement, while, the excitability of the underlying white substance remains unaltered.