336 SCIENCE PROGRESS 



These observations were to have commenced on October i, 

 1913, but considerable delay occurred in obtaining a supply of 

 the large number of soot and dust gauges (of a standard size 

 and pattern) required for the work, and the commencement of 

 the observations was delayed in consequence until March 1 

 of the present year. The health authorities of the following 

 twenty-five cities and boroughs are joining in the movement : 

 Aberdeen, Ayr, Birmingham, Coatbridge, Exeter, Glasgow, 

 Greenock, Hull, Leicester, Leith, Liverpool, London (3), 

 Malvern, Manchester, Newcastle-on-Tyne, Oldham, Paisley, 

 Plymouth, Sheffield, Stirling, Wishaw, and York. Hamburg 

 is also commencing similar observations by the standard 

 method, the very active Smoke Abatement Society of that city 

 having agreed to take charge of these observations. 



The principle of the apparatus and method that have been 

 selected by the committee, after careful examination of all that 

 have been tried for the purpose, is that of collecting the soot 

 and dust and other impurities that fall by their own weight, or 

 are carried down by the rainfall in a given area, in one month, 

 in a large collecting gauge of enamelled iron. 



This method does not give, it is true, the amount of solid 

 matter suspended in the air, at any given moment of time. 

 There is, however, a close relationship between the amount of 

 solid matter that falls, or is carried down by the rain, in a stated 

 period, and the amount in suspension — and the former may be 

 taken without serious error as an index and measure of the 

 latter. The apparatus used is therefore simply an enlarged 

 rain-gauge, the catchment area being increased to four square 

 feet, and several large bottles, connected by syphons, being 

 provided to hold the collected solid and liquid matter. The 

 gauges are placed on the ground level, in open spaces free from 

 abnormal dust. The bottles containing the water and deposit 

 are removed on the last day of each month, and are replaced by 

 thoroughly cleaned empty bottles. Before removing the bottles 

 the gauge vessel is washed down with some of the collected 

 water, a brush being used to remove any adherent matter. A 

 chemical analysis of the water and deposit is then made by a 

 standard method, details of which have been settled by the 

 committee. The analysis will reveal the relative proportions 

 of carbonaceous matters and of tarry matters in the solid deposit, 

 and will enable the committee to judge how far the domestic 



