900
��Popular Science Monthly
��is the only city where people habitually have their wall paper cleaned once or twice a year by a professional cleaner. The city was spending more than $730,000 for artificial light in the daytime.
Stringent smoke-abatement ordinances were adopted in 1914, and in the following year it was reported that the amount of smoke emitted had been reduced 75 per cent. Pittsburgh has a Smoke Bureau,
��smoke. Thus many American cities pro- hibit "dense smoke," or "black, thick and continuous smoke," or smoke intercepting a certain percentage of light. But it appears that while the adoption of anthracite coal or coke as fuel will render the discharge of smoke less visible, it will not materially reduce the emission of dust or fine cinder. Another important point brought out by the Chicago investigations is the extent to
���Pittsburgh's sootfall map. To determine the amount of solid matter or soot in the atmosphere, its distribution and composition, stations were selected in various parts of the city. The weight of the sootfall in grams at each station for each month was calculated. Pittsburgh's annual soot- fall was found to be 1,031 tons per square mile. That of Leeds, England, is from 26 to 539 tons
��which costs the city $i i ,000 per annum, and which now effects an annual saving to the community of several million dollars. The methods adopted to diminish the smoke include changes to gas, coke and low- volatile coals, installation of down-draft boilers, inclined chain-grate stokers, under- feed stokers, steam jets and extension stacks. Another city in which elaborate investi- gations have been made is Chicago. Dr. W. F. M. Goss, of the University of Illinois, who directed these studies, brought out several interesting facts, one of which is that too much importance has generally been attached to the mere visibility of
��which the atmosphere of a great city is polluted by forms of dust not due to smoke. Exact measurements of the amount of solid matter contributed to the atmosphere by smoke have been made more extensively in Europe than in America. Measure- ments of sootfall made at twelve stations in Pittsburgh in 1912-13 indicated an annual average deposit of soot in that city amount- ing to 1,031 tons per square mile. In Leeds, England, the sootfall ranges from 26 to 539 tons per square mile in different sections of the town. London's average is 248 tons for the whole city and 426 tons in the central districts. In the center of Glasgow
�� �
