ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 233 



from the combined effect of smoky fog and cold. The present author 

 was in London during the whole period, and noted especially the unus- 

 ual number of days during which the darkness and stillness continued, 

 and the tenacity with which the fog clung to the cold ground on the 

 shady sides of squares and streets, when a warm, gentle current from 

 the south improved and cleared the air above a height of 20 or 30 feet. 1 

 The large excess of carbonic acid, of sulphurous acid, and of micro- 

 organisms and effete organic products was partly concerned in these 

 ill effects, but the factor of greatest importance was the finely divided 

 and thickly distributed carbon or carbonaceous matter, which irritated 

 the breathing passages and lungs. The results corresponded rather 

 closely with the more gradual ill effects of dusty trades. The lungs of 

 a man who has spent his life in London or Manchester are found, post 

 mortem, to be choked with black matter. In some parts of London 

 there is sometimes no more light at noon than in the darkest night. 

 After a fortnight of dense fog the deaths in London for one week, end- 

 ing January 2, 1892, exceeded by 1,484 the average number, being at 

 the rate of 42 per 1,000. Increases took place in the following diseases : 

 Measles, 114 per cent; whooping cough, 173; phthisis, 42; old age, 36; 

 apoplexy, 58; diseases of the circulatory system, 106; bronchitis, 170; 

 pneumonia, 111; other respiratory diseases, 135; accidents, 103. 



These results are in the main attributable to the concentration of the 

 ordinary constituents of London air, with moisture and intense cold to 

 help their deadly work. The majority of the fatal cases were in 

 weakened constitutions, though many were among the robust. The 

 experience of large towns always is that the power of recovery after 

 illness is much less within their confines than in the country. In the 

 fog the evil influences of town air are many times multiplied. The 

 blackest fogs, which are local, are the result of variable or Opposing 

 currents which carry up the discolored mass to a height of hundreds 

 of feet, where they condense their moisture in a stratum of unusual 

 thickness or height. By a converging flow of currents, a huge column 

 of blackened fog particles rises vertically to a height where it may 

 remain or whence it may move slowly from place to place. A fog need 

 not always be resting on the ground, but may hang after the manner 

 of stratus cloud at some level, often a few hundred feet above it. This 

 happens when the ground is not much colder than the air. The smoke 

 of a steamer may be seen sometimes thus to form a dark streak, remain- 

 ing about the same level for an hour or more. That domestic fires at 

 least rival manufacturing works in the production of dark fogs is 

 proved by the intense darkness which has prevailed in London on Sun- 

 days, and once on Christmas Day. Factory fires are out on Sundays, 

 but domestic fires are larger and more numerous. Smoky fogs invade 

 houses and even warm rooms, showing that many of the nuclei are 

 solid particles large enough visibly to obstruct light even when dry. 



1 London Fogs. R. Russell. Published by Stanford, London, 1880. 



