In 46,077 deaths from scarlet fever in England in 1841 and 1842, and in London in the years 1838, 1839, 1840, 1843, 1844, 1845, 1846, 1847, and 1848, the proportions of deaths in the seasons of those years run as follows:

No. of deaths... 9,068......11,914......14,630......10,465......46,077 Percentage...... 19 679......25-856......31·751......22-711

Derived

The above table requires no comment. from an immense number of cases, the inference to which it leads, viz., that scarlet fever is most prevalent in this country in the last three months of the year, least so in the months of April, May, and June, is obvious. One word I must add. If the reader could see an analysis of the above tabular statement, he would find that the rate of mortality is not always the same in the special quarters of the years specified. So that a calculation made from one or two, or even three, of those years would be likely to lead into a grievous error. When, however, the trouble is taken to reduce the returns of a great number of years to a single calculation, we approach as near to the truth as absolute knowledge can carry us.

The correctness of these results is, moreover, singularly confirmed by the calculations of Dr. Tripe. In a paper in the Transactions of the Epidemiological Society for 1857, Dr. Tripe takes up the statistics of scarlet fever from 1840 to 1856, as they are recorded in the returns of the English Registrar-General. The

summary of Dr. Tripe's labours in this direction was as follows:

"Of the total mortality in the years 1840-56, viz., 33,451, 6042 deaths happened in the spring, 7910 in the summer, 11,706 in the autumn, and 7793 in the winter quarters; or in the following ratio, 18.0 per cent. in spring, 23.6 per cent. in summer, 35.2 per cent. in autumn, and 23.2 per cent. in winter. This disease is, therefore, by far more fatal in autumn than in any other season, and, as before shown, rages most furiously from the middle or end of September to the middle of November; the largest number of deaths having occurred in October. I put the percentages in a tabular form.

Percentages of Deaths from Scarlet Fever.

"The variation in rate of death in the quarters of the two periods under examination was much less than in either measles or small-pox. In the spring quarters of 1840-49, the rate was 17.7, and of 1850-56, 18.5 per cent.; in the summers of 1840-49 it was 24.8, and of 1850-56, 22.2 per cent.; in the autumns of 1840-49 it was 35.6, and of 1850-56, 34.3 per cent.; in the winters of 1840-49 it was 21.9 per cent., and of 1850-56, 25.0 per cent. From these data it is evident that the greatest mortality from scarlet fever occurs in autumn, and the smallest in spring. The variation in the rate of mortality was greatest in the winter quarters; for in the winters

F

of 1840-49, out of each 100 deaths, 21.9 per cent. occurred, whilst in 1850-56 no less than 250 per cent. happened.

"The rate of death in the two periods was by no means alike; 1858 deaths having been registered in each year of 1840-49, and 2124 in each of the years 1850-56, being an excess of one-seventh. This has arisen from the disease having assumed an epidemic form at shorter intervals than usual."

Now, in considering season and its influences, what are we to interpret from it? The term is too wide to be in any degree definite as a cause of disease. What is there in season to determine the origin and modify the course of a pestilence such as scarlet fever? I confess I am unable to tell; for, when the broad affirmative fact is established, all in the way of detail is negative.

I did, indeed, once with great labour endeavour to analyse the facts bearing on this question. I sought through the meteorological changes of season for an explanation of the prevalence of this one disease at particular periods. Was there anything in temperature, in barometrical pressure, in rain, in the electrical conditions of the air, and, above all, in the movements of the winds, that could influence the course of the disorder? It was a painful failure, this research; and I will show it in its failure. After various endeavours to arrive at results which should be to my mind satisfactory, I determined at last to find certain periods when the disease in one given city, say London, should present in a given time, say a

week, the same rate of mortality. This, as the nearest approach both to the prevalence and intensity of the disorder at fixed times, afforded the means of measuring a standard of the disease by a standard of the meteorological states presented during the same times. I found, then, twelve weeks, viz., the weeks ending January 17th and April 4th, 1846; January the 2nd, April the 10th, June the 19th, July the 3rd and 31st, and August the 7th and 14th, 1847; and January 11th, February 1st, and March 15th, 1851; in all of which the mortality from scarlet fever was sixteen cases per week. I found five other weeks, viz., the weeks ending November the 2nd, 1850; September the 20th and 27th, and December the 20th, 1851; and January the 3rd, 1852; in each of which the mortality was forty-one per week. And finally, I selected two weeks, the one of extremely high, the other of extremely low mortality. The week ending October 14th, 1848, represented the first of these, for in this week there were one hundred and eighty-eight deaths; the week ending April the 18th, 1851, represented the second of these, there being only eight cases recorded.

Analysing these cases of death, and subjecting them to careful study by the side of the meteorological conditions, I constructed a table, of which the following is an abstract.

In the twelve weeks in which the mortality was sixteen per week, the mean temperature varied as much as 36°; one of the weeks having a mean of 65°, another of 29°. In the five weeks in which the deaths each

week were forty-one, the range of temperature was from 36° to 57°, giving a difference of 21°. In the week when the mortality was extremely high, viz., one hundred and eighty-eight, the temperature was 52°; whilst in that week in which the mortality was so low as eight, the mean temperature was 46°.

Turning from the thermometer to the barometer, I found an equal want of relationship. In the twelve weeks where there was an equal mortality per week of sixteen, there was a range in the barometrical readings varying from 30-277 to 29-435, or 0.842. In the weeks in which the mortality was forty-one, the reading varied from 30-190 to 29 625. In the week with the high mortality, one hundred and eighty-eight, the mean barometrical reading was 29-824; while in the week with the low mortality, eight, the reading was 29-776.

The Amount of Rain. In the twelve weeks of equal mortality of sixteen, the extremes were 1·61 to 0·00. In the five weeks in which the mortality was fortyone, the rain fall was 0.15 to 0.00. In the week of the high mortality, one hundred and eighty-eight, the fall was 3.42; and in the week of the low mortality, eight, it was 0.02.

The Rate of Atmospheric Movement. In the weeks of equal mortality of sixteen per week, the difference was most varied; in one week there was absolute calm, in another the atmospheric movement had a mean of 207.857 miles per day. In the weeks with an equal mortality of forty-one, the range of atmospheric motion was from 428 to 975 miles per week.