Codd. Engineering News, Apr. 26, 1894.

A description of a filter at Nantucket, Mass.

Cramer. Centralblatt für Bauwesen, 1886, p. 42.

A description of filters built at Brieg, Germany.

Crook. London Water-supply. London, 1883.

Delbruck. Allgemeine Bauzeitung, 1853, p. 103.

A general article on filtration; particularly valuable for notices of early attempts at filtration and of the use of alum.

Deutsche Verein von Gas- und Wasserfachmänner.

Stenographic reports of the proceedings of this society are printed regularly in the Journal für Gas- und Wasserversorgung, and the discussions of papers are often most interesting.

Drown. Journal Association Eng. Societies, 1890, p. 356.