File:The character and extent of air pollution in Leeds - diagram of the apparatus employed for estimating the solid matter in Leeds air.png

English: diagram of the apparatus employed for estimating the solid matter in Leeds air. A is a leaden tube fixed through one of the windows of the Philosophical Hall, about 18 feet above the ground, and overlooking a side street where there was practically no traffic. Through a cork diaphragm within this, is fixed an open glass tube, B, consisting of a wide portion in front, and a narrow tail piece. The wide portion contains a carefully weighed plug of cotton wool, which filters the air and collects the solid matter. This plug was always dried and weighed against a similar plug. The glass tube, B, is connected with an empty bottle, C, and a Desaga water-jet aspirator, D, which is fixed into a large wash tower, E, so that air can be aspirated through B and C, and delivered to the experimental gas meter F for measurement.