Page:Popular Science Monthly Volume 45.djvu/886

864 whole of tropical Africa and southern Asia. They have lost their original language, and have been encroached upon by surrounding tribes, even within the dense forests to which they retired, until they are met with only in scattered remnants. No trace of degeneracy is to be found among them, for, according to the accounts, they are well proportioned "and certainly not rachitic."

is adduced in Nature, by J. Howard Mummery, contradictory of the hypothesis that caries of the teeth is a modern disease and confined to civilized races. The author's father, in a communication to the Odontological Society in 1870, brought together the results of an inquiry extending over more than ten years, in which he examined more than two thousand skulls, and was brought to very different conclusions. Among thirty-six Egyptian skulls, caries was found in fifteen (41·66 per cent); among seventysix Anglo-Saxon, twelve (15·78 per cent); among one hundred and forty-three skulls of Romano-Britons, forty-one (28·67 per cent); and among forty'-four miscellaneous skulls of ancient Britons, 20·45 per cent, showed carious teeth. Of modern savage races, among the Tasmanians, 27·7 per cent, of caries was found; among native Australians, 20·45 per cent; among East African skulls, 24·24 per cent; and among the skulls of West African natives, 27·96 per cent.

are protected in India against the attacks of insects by pouring a few teaspoonfuls of refined mineral naphtha, or benzine collas, into the crevices of the binding, and then shutting up the volume in a close-fitting box. They have to be afterward sprayed over lightly with the finest kerosene oil, which should be rubbed off before it penetrates the binding. Another way is to brush the books over with a saturated solution of corrosive sublimate. In the Indian Museum Library the books are kept in close-fitting glass cases with a few ounces of naphthaline upon each shelf. The paste used in binding these books is also poisoned with sulphate of copper.

the Kelvingrove Museum, Glasgow, is a crow's nest from Rangoon made of iron wire, such as is used in fastening the corks of aerated water bottles. Mr. Campbell, of the museum, quotes from the donor of the curiosity, who says that such nests can always be obtained from high trees in the vicinity of the factories of aërated water.

extensive series of minute chipped stone implements from India, which has lately come into the possession of the United States National Museum, is described by Curator Thomas Wilson as comprising every condition of the implement and having the single peculiarity, in which these differ from other prehistoric implements, of remarkably small size. The cores are rarely more than an inch and three quarters in length, and the blades are rarely more than an inch and a quarter or an inch and a half, the majority of them being not more than an inch, while the finished specimen is frequently not more than five eighths of an inch in length. The finished implements are of various forms—slim, almost needlelike, triangular, with a base convex, straight, or concave, quadrilateral, trapezoid, rhomboidal, while the most delicate and finely finished are in the form of a crescent.

their woodcut engraving, according to Mr. T. Tokuno, of the United States National Museum, the Japanese artists strive to imitate the original, even to the sweep of the brush, so closely that it shall be difficult for an inexperienced person to detect the difference, and they have been wonderfully successful. The methods employed by them are those used in Europe in the fifteenth, sixteenth, and seventeenth centuries. The material is wood cut in the direction of the fiber, or planks, for which since Bewick's time blocks cut across the fiber have been substituted with us.

chief features of the Karst (limestone) regions of eastern Europe, according to Dr. Jovan Cirjic, are those known as karren dolinen, blind valleys, and poljen. The karren are surfaces composed of blocks of limestone separated by narrow fissures. The dolinen, called by English writers swallow holes, sink holes, or cockpits, are rounded hollows varying from thirty to more than three thousand feet in diameter and from six feet to three hundred and thirty feet in depth, and great numbers of them often occur in a limited space. They may be dish, funnel, or well shaped, or of other forms. Besides the simple basins, the dolinen also occur in the form of chimneys communicating below with blind cavities or with underground river courses or systems of fissures. The first are known in France as avens, and the second in Jamaica as light holes.

the Mining School at Houghton, which had one hundred and one pupils in 1893, Michigan claims to possess the largest school of mining engineering in the United States. The school also excels in the number of graduates in proportion to its age. Its pupils are mostly farmers' sons, and twenty-three States and foreign countries are represented among them. Its equipment has been planned with the idea of providing the means for each student to occupy his entire time without obliging him to wait, and of making the laboratory take the place, to a large extent, of instructors. Candidates for admission are expected to be proficient in the use of the English language and in the special subjects required, including the solution of practical problems in mathematics. A three years' course is prescribed.