THE MICROBES OF THE AIR 273 



(b) that there are a larger number of microbes in 

 the atmosphere during the summer than any other 

 period of the year. Miquel has also shown that as 

 the number of microbes in the atmosphere increases, 

 so does the mortality from zymotic or infectious 

 diseases. 



The investigations of Dr. P. F. Frankland on 

 aerial microbes have added considerably to our 

 knowledge of this interesting subject. Frankland 

 has not only examined the air so as to ascertain the 

 number of microbes present in a known volume, but 

 he has discovered many new forms. 1 



Frankland has obtained the following results 

 concerning the number of microbes present in ten 

 litres, or two gallons, of air at different places : 



Primrose Hill (top), ... 9 



(bottom), . . 24 



Norwich Cathedral (top of spire, 300 ft. ), . 7 



(tower, 180ft.), 9 



,, ,, (in the close), . . 18 



St. Paul's Cathedral (Golden Gallery), . 11 



(Stone Gallery), . 34 



' (Churchyard),. 70 



>> f Reigate Hill, . 



J Heath near Norwich, 



q g I Garden at Reigate, . . 25 



I Garden near Norwich, . . 31 



g [ Kensington Gardens, . . .13 



-2^ { Hyde Park, . . 18 



^ j I Exhibition Road, . . 554 



Frankland has also shown that within doors the 



1 Philosophical Transactions, vol. clxxviii. p. 257. 



