Societies and Academies

Abstract

LONDON. Royal Society, Feb. 23.—Sir Leonard Rogers: The yearly variations in plague in India in relation to climate: Forecasting epidemics. The seasonal incidence of plague in India depends on monthly variations in mean temperature and humidity, expressed as saturation deficiency, as pointed out by St. John Brooks. Mean monthly temperature variations in hot weather and monsoon periods influence subsequent plague, through high temperatures reducing, and low ones favouring, its prevalence. Saturation deficiency in cold weather as well as in the hot season influences plague incidence, through high saturation deficiency, indicating low relative humidity, reducing prevalence of plague, and vice versa. The great yearly variations in plague can nearly all be explained by the influence of these climatic factors. In the three northern areas, Punjab, United Provinces, and Bihar, four of the six climatic factors become evident before the annual increase of plague from December onwards, and thus allow the more important yearly increases and decreases to be forecast, as a rule. This is also the case to a large extent in Central Provinces. In Deccan, with early increase of plague during monsoon months, forecasts are of less value.