240 ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 



Natural History Museum, Entrance Hall, Wliitnionday 1, 755 



Hospital for Consumption, raorniug 18 



Hospital for Consumption, afternoon 66 



Railway compartment, open window, 4 persons 395 



Railway compartment, window 4 inches open, 10 persons 3, 120 



In experiments made with the object of finding' the number of 

 microbes in a certain volume of air, be found at a height of 300 feet on 

 Norwich Cathedral, only 7 in 2 gallons; on the gravel near the cathe- 

 dral, 18 ; at the top of Primrose Hill, 9 ; at the foot, 24. 



Dr. Fischer found, in experiments made at sea, that at 120 miles 

 from land, in eleven out of twelve experiments, the air was quite free 

 from germs; that at 90 miles from land, in seven cases out of twelve, 

 there were germs, but very few. Practically it appears that at 120 sea 

 miles distant from land the air is pure and free from microorgauic life. 



Angus Smith roughly calculated the amount of organic matter, living 

 and dead, to weigh, in pure air on high ground, 1 grain in 209,000 cubic 

 feet; in a bedroom, 1 grain in 64,000 cubic feet; in a closely packed 

 railway carriage, 1 grain in 8,000 cubic feet. 



He obtained some curious results by shaking up air in different places 

 with water. The air of a cowhouse gave an effect only produced by 

 fifty to one hundred times the quantity of good air, and contained a 

 mass of debris, hairs, etc. The air behind houses in streets was worse 

 than in front of them. 



Moisture collected from the air above marshes has been found by 

 Italian observers to contain multitudes of seeds of algae and of micro- 

 scopic infusoria. The condensed dew exhibits a surprising quantity of 

 spores and sporangia. 



Other observers agree in noting decaying organic matter in abun- 

 dance, vaporous and solid, together with living minute forms of animal 

 and vegetable life, floating in the air; these consist of algae, diatoms, 

 fungi, bacteria, and other microorganisms. 



The subtilis, or bay bacillus, is always- present in the open air, but 

 the bacilli generally keep to low levels and do not extend so high as 

 the mold fungi. 



Cunningham, at Calcutta, found spores and other cells constantly 

 present in the free air, usually in considerable numbers. The majority 

 were living, capable of growth, and seemed iudependent of moisture 

 and direction of wind. 



Mr. Greenleaf Tucker found that outside the City Hospital of Boston 

 10 liters of air contained on an average 10 colonies of bacteria, 7 of 

 molds, in November; 13 of bacteria and 3 of molds in January. The 

 number of bacteria was less on rainy days. The hospital itself con- 

 tained few bacteria, owing to constant care and cleanliness, but the 

 number was much increased after sweeping and bedmaking. 



Carnelley found in clean one-roomed houses 180 bacteria per 10 liters; 

 in dirty houses, 410; in very dirty, 930; in schools, from 300 to 1,250, 

 according to ventilation; in the Koyal Infirmary, Dundee, 10 to 20. 



