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THE POPULAR SCIENCE MONTHLY.

the upper surface of the cutter-plate. By this operation a new clean surface is constantly produced on the filter-bed, practically starting a new filter, at each revolution of the cutter-plate. A model machine, when tried with common sewer-waters at Asnières, near Paris, having a filter-bed of 978 inches in diameter, filtered eight litres, or 1·761 gallons, in a minute under a pressure of one atmosphere and a half. In the same proportion the rate of filtration with a bed one foot in diameter would be 3·31 gallons a minute, and with a bed ten feet in diameter 260 gallons a minute, or 374,400 gallons a day of twenty-four hours. Applied to the water-supply of towns, a machine having a filter-bed ten feet in diameter should filter, under a pressure of one atmosphere, 466,560 gallons in twenty-four hours.

 

Origin of Diphtheria.—The observations of Mr. G. H. Fosbrooke, medical health-officer of Birmingham, England, have led him to form conclusions respecting the etiology of diphtheria which differ in some points from those which have been urged by other authorities. He regards it as a well-established fact, confirmed by his experience, that the disease is more common in rural than in urban districts, and has observed that even when it has prevailed extensively in a rural district, and has thence been conveyed into a neighboring town, it has not spread in the town. In one town of five thousand inhabitants, diphtheria, when it occurred, prevailed concurrently with typhoid fever or scarlatina, giving rise to the suggestion that all those diseases might originate in a common poison. Mr. Fosbrooke does not agree with other authorities as to the conditions of soil most favorable to the propagation of diphtheria. Generally the disease has been thought to flourish most in damp situations and in connection with damp subsoils. All of his attempts to associate its origin and distribution with any peculiar soil or situation have failed, for he has met it both in villages occupying elevated and airy situations and in low places. The most serious epidemics and the larger number of cases of which he has had personal knowledge have appeared on soils that were "rather gravelly and well drained." With one exception, his experience opposes the idea that houses shut in by trees are more liable to harbor the disease than those which are not surrounded by an abundant vegetation. The fluctuations of diphtheria, when it prevails for any considerable length of time, do not appear to be influenced by changes of season or by variations of weather. Meteorological observations, made with reference to this point, differ widely, and furnish no guide to an opinion. The disease is generally found first to break out in October, and to prevail as an epidemic, when it does so prevail, in the winter months, increasing, as is natural with epidemics, during the earlier months of its course, but without regard to the regularity or irregularity of the season.

 

Anthropology in Russia.—Anthropology has made much progress in Russia. The Imperial Society of the Friends of Natural Science, Anthropology, and Ethnography, founded in 1863, of which Bogdanof is the master-spirit, has done good service in assuming the patronage of investigations among the numerous diverse stocks of whom the Russian nationality is composed, and in encouraging measures to bring the interests of anthropology before the public. The Anthropological Exhibition, which was held at Moscow last summer, had this object prominently in view, and was further intended to promote the establishment of a professorship of anthropology, and of an anthropological museum. The collections exhibited and reported upon embraced skulls, skeletons, relics, prehistoric and modern, and articles of various kinds, illustrating the character, condition, and customs of the ancient and modern inhabitants of the empire. Among the neolithic stone implements from Kazan were hatchets, crossed by a groove in which to fasten the handle, precisely as in the North American hatchets, and arrow-heads, both with and without shafts. Fragments of urns bearing the well-known pack-thread ornament and bronzes of the so-called Tschudic type were shown from the Volga. Filimonof brought from the Caucasus, where he has been digging under the auspices of the society, great bronze whorls, of similar form to those which are met in the Baltic provinces, but