Page:The character and extent of air pollution in Leeds - (A lecture delivered before the Leeds Philosophical Society, on March 3rd, 1896.) By Julius B. Cohen (IA b21534160).pdf/21

21 PART II.

N account of the impurities in the air of a large town would be incomplete without some allusion to that busy and invisible population—the microbes—their numbers and their favourite haunts. The method, which I have used for collecting and counting them in different parts of Leeds, is that described by Professor Percy Frankland (Phil. Trans. 178, 257).

I have devised a slightly modified apparatus, so as to render it more portable.

In order to collect samples of air, and compare the numbers of microbes contained in them with those of open places, like Woodhouse Moor, several rounds of visits have been made to different parts of Leeds, including the courts and yards in "the insanitary area." The experiments, as far as they have been carried, agree with what might have been anticipated. The enclosed and dirty courts are more thickly inhabited by these organisms than the more open and cleaner places.

Samples taken on Woodhouse Moor, and on the tennis court of the Yorkshire College, in January and February of the present year, gave on the average 11 bacteria in 1 cubic foot of air, whilst the samples drawn from the slums, on the same days, contained on the average six times this number. These experiments are still in progress.

It does not follow that these microbes are injurious, but there is no doubt that where they find a fruitful soil for growth, in such places we may expect disease germs to flourish.

Considering what an energetic and progressive community we are, I think we exhibit an unusual amount of deliberation in dealing with the delicate problem of the removal of these