1881. 



on the Weather and Health of London. 



G37 



in the amplitiulo of its annual rage, tho greatest sensitiveness to 

 weather, and pneumonia tho least. They all nhow, though in 

 different degrees, a double-ridged maximum : the one ridge being in tho 

 middle of January, when the temperature falls to the annual minimum, 

 and the other in March, when the combined qualities of cold and dry- 

 ness are at the annual maximum. Asthma and bronchitis are de- 

 cidedly at the maximum when tho weather is coldest, whereas 

 laryngitis has its maximum in March, when tho weather is coldest 

 and driest, the last disease thus forming the link connecting the more 

 strictly throat diseases with diseases of the nervous system. 



Fig. 14. 



Jan. Feb. March. April. May. June. July. Aug. Sept. Oct, .Nov. Dec. 

 130 n 1 I 1 I ! 1 till I M I r I I I I I Ml III I t n I I I III III 



1 



Mean 



~1 t I I 1 I 1 I I I I 111 Ml 1111 111 111 1 1 1 I L 1 I I I II iJ I I 

 Pneumonia. 



Fig. 15. 



50U I I 



ill I II 1 11 



Laryngitis. 



But an element of weather other than mere temperature plays an 

 important part in bringing about the high death-rate from these 

 diseases. That deleterious atmospheric influence is fog ; and in cases 

 where the fog is dense and persistent the mortality from diseases 

 of the respiratory organs becomes truly appalling, as happened 

 in London in 1880, when the mortality was nearly doubled. An 

 examination of the fogs of London shows that they do not commence 

 till the autumnal equinox ; and it is at this epoch that asthma (Fig. 

 12), which is by far the most sensitive of all diseases to fog, starts 

 from its annual minimum j and in the end of November and beginning 



