278 Dr. P. F. Frankland and Mr. T. G. Hart. 



© 



Number of 

 micro-organisms 

 falling on 

 1 horizontal 

 square foot 

 per minute. 



8555 



05 

 CM 



CO 

 tH 



05 



i> 



Number of 

 colonies from 

 10 litres of air 



(calculated) . 





O 

 CO 



TP 



iH 



(M 

 CO 



CO 



Number of 

 colonies 

 obtained from 

 given volume 

 of air. 



CD 

 | 

 O 



30 in 10 lits. 

 16 moulds 



13 in 9 lits. 

 11 moulds 



32 in 10 lits. 

 14 moulds 



9 in 11 lits. 

 6 moulds. 



Conditions of experiment. 



1 



Barn, near Hughenden, Bucks. One man thrashing rye 

 with flail, doors wide open, dish exposed 3 feet from 

 ground. 



North Chemical Laboratory, Science Schools, South Ken- 

 sington. About 40 students had been working until half- 1 

 an-hour previously. Almost empty at time of experiment. | 

 16-9° C. 



North Chemical Laboratory. As it was Saturday, only 

 12 students had been working in the morning, and had 

 left about 1 hour previously, the laboratory being quite 

 empty. 16 9° C. 



Private Laboratory, Science Schools. Windows and door 

 closed, 3 persons in room, but not moving about. 

 16-9° C. 



Private Laboratory, Science Schools. Windows and doors 

 closed. 18-6° C. 



Date. 1886. j 



to 



so «aj 



is 



S * 



|S 



October 16th. 

 2.3—2.35 p.m. 



m a 



^ TP 



oq co 

 *«■ d 



tH 



November 12th. 

 3 — 4 p.m. 



