January 8, 1892.J 



SCIENCE. 



■27 



to tlie atmosphere an " epidemic constitution." The influence of 

 weather would be measured by its effect in providing an environ- 

 ment suitable to germ development. Tbus moist weather, 

 whether bleak or warm, would be found conducive to the spread 

 of contagia, and so it is. This fact has often been attested by the 

 extension of cholera, diarrhoea, and the exanthemata. A warm 

 and dry day, on the contrary, tends to check morbid action of an 

 infectious kind. This fact is susceptible of more than one expla- 

 nation. We may, on the one hand, says Lancet, regard it as a 

 consequence of the absence of that gtrm-fostering condiiion — 

 humidity; on the other, we cannot fail to be reminded that dry 

 warmth and sunshine give the signal for an exodus from many 

 crowded homes, for their freer ventilation, and consequently for 

 diminution in the intensity of contagia. The exact value of 

 weather changes in regard to this class of diseases, however, still 

 is and must for some time remain svib judice. As for the ailments 

 more usually associated with these changes — those, for example, 



more commonly known as inflammatory — the connection is here 

 much more evident, and also in all likelihood, more direct. The 

 association of pneumonia, bronchitis, asthma, and rheumatism 

 with bleak and wet weather is too invariable to permit of our 

 doubting its reality apart from any suggestion of septic agency. 



— Mr. Kehvay, according to Industries, has introduced an ex- 

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 Signalling by this means corresiwnds with the use of the black- 

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 read. 



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