liv proceedings of the royal horticultural society 



Scientific Committee, November 1, 1892. 



Dr. M. T. Masters in the Chair, and ten members present. 



Injuries to Plants by Fog. — Dr. Eussell observed that with 

 reference to carrying out any experiments, the subject must be 

 regarded from two points of view. Firstly, the object would be 

 to make an exhaustive investigation into the action of fogs upon 

 plants. This, to a considerable extent, the Scientific Committee 

 has already done, as shown in Prof. Oliver's published report,* 

 and in a second upon which he is now engaged. Secondly, 

 taking a wider aspect of the subject, the points which would 

 have to be considered w T ould be the composition of fogs in 

 general, their origin and extent, their comparative densities, the 

 amount of sulphurous acid, the consequent diminution of 

 light, &c. Such investigations would lead to the more univer- 

 sally important consideration as to the increasing unhealthiness 

 of London in winter. To carry out this extensive programme 

 would necessitate the selecting several stations, involving con- 

 tinuous observations, both during fogs and in clear weather. 

 The whole would require a staff of paid analysts. Dr. Eussell 

 then gave some interesting statistics of observations carried out 

 at Manchester by Dr. Bailey, which will in due time be published. 

 One point to which he alluded may be here mentioned — namely, 

 the amount of chlorides contained in " fog collections " washed 

 out of the air. He himself had found a dense precipitate of 

 chlorides even on Dartmoor, whenever sea breezes blew in that 

 direction. A propos of this, Prof. Church remarked that he had 

 on one occasion detected 7 grains of salt per gallon at Cirencester, 

 which was about thirty-five miles from the sea. It is evident, 

 then, that the presence of chlorides does not necessarily always 

 indicate the presence of sewage. Prof. F. Oliver observed thafc, 

 regarding the injuries from a horticultural point of view, the 

 question as to the best means of preventing the action of fogs 

 was most important. He described three methods. The first, 

 with which he was very favourably impressed as to its efficiency, 

 although it would probably prove to be the most difficult and 

 expensive, was as follows : The primary condition for success 



* " The Effects of Urban Fog upon Cultivated Plants," by Prof. F. W. 

 Oliver, D.Sc, F.L.S. Journ. Roy. Eort. Soc, vol. xiii., p. 139. 



