280 



Dr. P. 



F. Frankland and Mr. T. G. Hart. 



Number of 

 micro-organisms 

 falling on 

 1 horizontal 

 square foot 

 per minute. 



1255 



CO 



cq 



00 



CD /• — \ 



2 o 



g £ 



Number of I 

 colonies from | 

 10 litres of air 



(calculated) . | 



OS 



o 



CO 



<M 

 CO 

 rH 



00 

 rH 



1 1 



Number of 

 colonies 

 obtained from 

 given volume 

 of air. 



261 in 8 lits. 

 5 moulds 



158 in 12 lits. 

 17 moulds. 



20 in 11 lits. 

 3 moulds 



1 1 



Conditions of experiment. 



Natural Histori/ Museum Garden, adjoining Exhibition 

 Road. Wind S. Number of people passing along road 

 greater than in morning. 18° C. 



Natural History Museum Garden. Wind S., but not quite 

 so strong as on previous day. Traffic in road less. 175° C. 



Natural History Museum Garden. Wind N.W., very slight 

 and gentle. Heavy rain during greater part of morning. 

 Grass damp, roads wet, pavement dry. Wind blowing 

 across grass and not from road. 15 '5° C. 



Hughenden, Bucks. Naphill Common, covered with heather 

 and fern. Sunshine. Wind very slight. No rain since 

 previous day. 



Ditto. Garden, grass all round. 



Dafe. 1886. 



5g • 



00 S 

 ,3 ^ 



35 8 



| OJ 



i— 1 \o 



a TP 



August 20th. 



11 A.M. 



6.30 p.m. 



