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Article
December 16, 1911

THE SIMULTANEOUS AND CYCLIC APPEARANCE OF EPIDEMICS OF PNEUMONIA, GRIP AND ENTERITIS ON THE NORTHERN HEMISPHERE: AND THEIR SYNCHRONISM WITH SOLAR ACTIVITY CYCLES

Author Affiliations

SAN FRANCISCO

JAMA. 1911;LVII(25):1964-1967. doi:10.1001/jama.1911.04260120154002
Abstract

Before this Section in 1894, I read a paper on the influence of atmospheric pressure conditions on the prevalence of pneumonia,1 and I published a further study on this subject in 1908.2 My conclusions, based on my former research and with special reference to epidemics of pneumonia in Chicago and San Francisco during the five years, 1899 to 1904, I formulated thus:

Pneumonia is not merely a concomitant of the cold weather season. Its prevalence depends on anticyclonic weather, summer and winter, on the northern hemisphere, and not on low temperature. There is sufficient reason to assume that the quality of the air of an anticyclone changes in conformity with changes in the activity of the sun and that the prevalence of grip and pneumonia is subject to a specific quality of such air.

In support of these conclusions, I prepared charts† showing: first, the even temperature and

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