Deposit gauge

They have a large circular funnel on top, made of stone so as not to be corroded by acid rain and mounted on a simple wooden or metal stand, which drains down into a collection bottle beneath.

[5] The first scientific paper featuring deposit gauge measurements was titled "The Sootfall of London: Its Amount, Quality, and Effects" and published in The Lancet in January 1912.

[6][7] Thanks to the introduction of the deposit gauge, air quality in Britain was monitored systematically from 1914 onward and this played an important role in determining the effectiveness of efforts to control pollution.

[4] Although deposit gauges were inaccurate and their limitations were well known from the start,[1][12][13] their widespread introduction still represented a considerable advance in the study and comparison of pollution at different times of the year and in different places.

[4][14] In his book State, Science and the Skies: Governmentalities of the British Atmosphere, Mark Whitehead, a geography lecturer at Aberystywth University, has described the deposit gauge as "perhaps the most important technological device in the history of Britain's air pollution monitoring".