520 



Dr. P. F. Frankland. 



[June 10, 



In the table (p. 519), the results of the experiments made near 

 Reigate and in the vicinity of Norwich are recorded. 



These figures present a very marked contrast to those contained in 

 the previous table ; thus the average number of organisms found in 

 the country experiments amounts to only 14 in 10 litres, whilst 

 an average of 79 fell on 1 square foot in one minute. 



Particularly noticeable is the great relative freedom from micro- 

 organisms of the air collected on the heath near Norwich during the 

 comparatively warm weather of April last when the ground was dry. 

 In the experiments made both at Norwich and Reigate it will be 

 observed that the air in gardens was richer in micro-organisms than 

 that of the open country, although in the Reigate experiments of 

 May 23rd there were more on the dish exposed on the hill than in the 

 garden, but this is easily accounted for by the fact that the wind on 

 the hill was very much stronger than in the garden, the number 

 found in a given volume being very much less in the case of the air 

 on the hill. 



In the table (p. 521) are the results of the examination of the air in 

 Kensington Gardens, Hyde Park, and Primrose Hill. 



Prom these figures it will be seen that on the whole the number of 

 organisms found in the air of these open spaces is less than in that 

 collected on the roof at South Kensington, but greater than in the 

 experiments made in the country, although the number found in the 

 second experiment in Kensington Gardens is scarcely in excess of 

 anything found in the country p J aces. 



The average number of micro-organisms found in 10 litres amounts 

 to 24, whilst an average of 85 fell on 1 square foot in one minute. 



