THE POPULAR SCIENCE MONTHLY
of the soil was reflected in a great abnormal rise in the ground-water. But from August onward through the winter, and till the beginning of the year, the amount of rain and dew which fell was again far below the average, and the ground-water steadily decreased. In the middle of April, 1874, it again began to rise, and then the epidemic of cholera ceased. The abnormal fall of rain in August, 1873, in Munich had the same effect on the cholera there as the southwest monsoons regularly have on the disease in Calcutta. In the relative dryness which follows this excessive wetness the epidemic process is continued as a winter invasion.
Munich and Augsburg are very much alike in situation and in meteorological factors. Both places lie in a direct line not sixty kilometres apart. But that differences in the amount of rainfall may occur is proved by the year of cholera 1873. In Munich, in spite of the excessive fall, the amount for the whole year was hardly up to the average; in Augsburg the excess above the average was thirty per cent. In 1873 the rainfall at Augsburg approached to that of the average at Salzburg. The distribution of the rainfall was different in Augsburg as contrasted with Munich, and the same difference in the history of the cholera holds good of the two towns. Augsburg had an epidemic of cholera in 1854, but none in 1836 or 1873, when only a few isolated cases occurred. That Augsburg in place and time and in individual disposition is susceptible of an epidemic of cholera was seen in the year 1854, when about three per cent of the whole population was destroyed by the malady, while Munich lost that year but two and a half per cent. If the appearance of cholera in the two places mentioned differed only in the time required for the transit from one city to another, then the germs of cholera must pass either from Munich to Augsburg or vice versa. In the year 1836 Augsburg remained free from cholera, which infested Munich for six months. At that period no observations on the rainfall were made, but no doubt exists that cases of cholera passed, without isolation or disinfection, from Munich to Augsburg. These facts prove that cholera is a miasmatic disease, and may be wholly independent of human intercourse. For the year 1854 meteorological data are obtainable, and this year had as dry a season in Augsburg as in Munich, while at both places cholera prevailed. In the year 1873 the case was different. Then there were in Augsburg regulations for the prevention of the spread of cholera, without which precautions, be it noted, in 1836, Augsburg remained free from the disease. Nevertheless, cholera did not visit Augsburg in 1873, during which period stringent measures of prevention were also in full force at Munich. Such considerations lead to the logical conclusion that what saved Augsburg did not relieve Munich. Further, Munich remained free from visitation in the humid summer of 1866, when cholera prevailed in North Germany; so that no importation of cholera to Munich took place from the seat of war.