390 



SCIENCE 



[N. S. Vol. LIII. No. 1373 



In all 29 gages are in operation — distributed 

 as follows: Birmingbam 3, London 8, Glas- 

 gow 9, Soutbport 2, and 1 eacb at Kingston, 

 Malvern, ISTewoastle, Eoebdale, Eotbamsted, 

 St. Helens, and Sterling. Two more stations 

 are aibout to operate. 



Full returns bave been publisbed in tbe 

 Lancet. 



Tbe following data are given in tbis report : 

 , 1. Montbly deposits for tbe two stations rep- 

 resenting bigb and low deposits. 



2. Total solids deposited montbly at all sta- 

 tions. 



3. Mean montbly deposits for summer balf 

 years, i.e., April to September, 1918 and 1919. 



4. Mean montbly deposits for winter balf 

 years, i.e., October to March, 1918-19, and 

 1919-20. 



5 and 6. Classification of stations accord- 

 ing to amounts of elements. 



7 and 8. Totals of classified stations for 

 eacb element of pollution. 



9. Comparison of mean montbly deposit dur- 

 ing summer and winter. 



10. Average deposit of each element for eacb 

 month for two London and four Glasgow sta- 

 tions. 



Also six summaries and analyses. 



The station showing the highest mean 

 monthly deposit for tbe year is Southwark 

 Park, London, with 15.35 metric tons per 

 square kilometer, but it is said that probably 

 Newcastle or Rochdale, for which full year 

 results were not available, might have ex- 

 ceeded this figure. The lowest value was 3.17 

 at Malvern. 



The following table^ gives the mean monthly 

 deposits as selected stations: 



MEAN MONTHLY DEPOSIT IN METRIC TONS PER 

 SQUARE KILOMETER 



Meteorological Office 8.43 



FdBsbury Park 10.78 



Bavenseourt Park 14.09 



Southwark Park 15.35 



Hesketh Park 6.41 



Woodvale Moss 5.34 



2 Abridged. Full table gives quantities of tar, 

 carbonaceous matter, etc. 



Bellahoustou Park 8.87 



Botanic Gardens 10.91 



Queens Park 8.01 



Eiehmond Park 12.15 



Generally speaking there is evidence of a 

 considerable diminution of summer deposit in 

 practically all tbe districts. 



The highest deposit of tar in the London 

 group was in February, tbe lowest in May; 

 while in tbe Glasgow group tbe highest was 

 in November and tbe lowest in September. 

 This may be regarded as a normal distribu- 

 tion, as the winter months, including the two 

 highest deposits, are the time when domestic 

 fires are in operation, while tbe lowest deposits 

 occurring in May and September, are in the 

 summer months when fires are presumably not 

 required. In Glasgow there is a second mini- 

 mum in December and February. Wind 

 doubtless has a great influence on the quan- 

 tity of deposit, high winds sweeping it away 

 from the vicinity of its origin and calm 

 weather favoring deposit near the source of 

 impurity. 



Of tbe research work, tbe chief problem has 

 been accurate measurements of acidity in the 

 air. Automatic filters have been devised, hold- 

 ing 24^hour discs and many records bave been 

 made of impurities in London air. It has been 

 shown that there is a definite cycle in the dis- 

 tribution of the impurities during the 24 

 hours. From midnight to 6 a.m. tbe air is 

 practically clean of impurity, very little being 

 recorded except during fogs. At about 6 a.m., 

 when fires are lit, there is an increase in im- 

 purity continuing until 11. From 11 to 10 

 P.M. the quantity varies very little. At 10 it 

 begins to diminish rapidly and has almost dis- 

 appeared by midnight. 



The committee is considering the possibility 

 of utilizing standard rain gages. For large de- 

 posits this might work, but for country places 

 with small deposits tbe 20 cm. gage (8 inch 

 diameter) would not suffice since tbe area of 

 tbis gage is practically 1/10 that of the stand- 

 ard deposit gage. One great objection to the 

 use of the standard rain gage is the imi>ossi- 

 bility of estimating the quantity of tar and 



