The above mentioned experiments being objected to on certain grounds, they were repeated by Piefke alone, confirming the previous observations on the passage of bacteria through filters, but under other conditions. —— Zeitschrift für Hygiene, 1894, p. 151, Über Betriebsführung von Sandfiltern. A full account of the operation of the Stralau filters in 1893, with discussion of the efficiency of filtration, etc. PLAGGE AND PROSKAUER. Zeitschrift für Hygiene, 11. p. 403. Examination of water before and after filtration at Berlin, with theory of filtration. REINCKE. Bericht über die Medicinische Statistik des Hamburgischen Staates für 1892. Contains a most valuable discussion of the relations of filtration to cholera, typhoid fever, and diarrhœa, with numerous tables and charts. (Abstract in Appendix II.) REINSCH. Centralblatt für Bakteriologie, 1895, p. 881. An account of the operation of the Altona filters. High numbers of bacteria in the effluents have often resulted from the discharge of sludge from the sedimentation-basins onto the filters, due to the interference of ice on the action of the floating outlet for the basins, and this, rather than the direct effect of cold, is believed to be the direct cause of the low winter efficiency. The author urges the necessity of a deeper sand-layers in no case less than 18 inches thick. RENK. Gesundheits-Ingenieur, 1886, p. 54. —— Über die Ziele der künstliche Wasserfiltration. RUHLMANN. Wochenblatt für Baukunde, 1887, p. 409. A description of filters at Zürich. SALBACH. Glaser’s Annalen, 1882. Filters at Groningen, Holland, built in 1880. Alum used. SAMUELSON. Translation of Kirkwood’s “Filtration of River-waters” into German, with additional notes especially on the theory of filtration and the sand to be employed. Hamburg, 1876. SAMUELSON. Filtration and constant water-supply. Pamphlet. Hamburg, 1882. —— Journal f. Gas- und Wasserversorgung, 1892, p. 660. A discussion of the best materials and arrangement for sand-filters. SCHMETZEN. Deutsche Bauzeitung, 1878, p. 314. Notice and extended criticism of Samuelson’s translation of Kirkwood. SEDDEN. Jour. Asso. Eng. Soc., 1889, p. 477. In regard to the sedimentation of river-waters. SEDGWICK. New England Water-works Association, 1892, p. 103. European methods of Filtration with Reference to American Needs. SOKAL. Wochenschrift der östreichen Ingenieur-Verein, 1890, p. 386. A short description of the filters at St. Petersburg, and a comparison with those at Warsaw. STURMHÖFEL. Zeitschrift f. Bauwesen, 1880, p. 34. A description of the Magdeburg filters, with plans. TOMLINSON. American Water-works Association, 1888. A paper on filters at Bombay and elsewhere. TURNER. Proc. Inst. Civil Engineers, 1890, c. p. 285. Filters at Yokohama. VAN DER TAK. Tijdschrift van de Maatschapping van Bouwkunde, 1875(?).