864 



THE POPULAR SCIENCE MONTHLY 



whole of tropical Africa and southern Asia. 

 They have lost their original langiiage, 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." 



Evidence is adduced in Nature, by J. 

 Howard Mummery, contradictory of the hy- 

 pothesis 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 18V0, brought to- 

 gether the results of an inquiry extending 

 over more than ten years, in which he exam- 

 ined 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 seventy- 

 six Anglo-Saxon, twelve (IS-TS per cent); 

 among one hundred and forty-three skulls of 

 Romano-Britons, forty-one (28-6'7 per cent) ; 

 and among fortj'-f our miscellaneous skulls of 

 ancient Britons, 20-45 per cent, showed cari- 

 ous teeth. Of modern savage races, among 

 the Tasmanians, 2*7-7 per cent, of caries was 

 found ; among native Australians, 20-45 per 

 cent ; among East African skulls, 24-24 per 

 cent ; &nd among the skulls of West African 

 natives, 27-96 per cent. 



Books are protected in India against the 

 attacks of insects by pouring a few teaspoon- 

 fuls 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 pene- 

 trates 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. 



In 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 al- 

 ways be obtained from high trees in the 

 vicinity of the factories of aerated water. 



An extensive series of minute chipped 

 stone imi)lements from India, which has late- 

 ly 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 rarelv 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, quadrilat- 

 eral, trapezoid, rhomboidal, while the most 

 delicate and finely finished are in the form of 

 a crescent. 



In their woodcut engi-aving, according to 

 Mr. T. Tokuno, of the United States Na- 

 tional 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 differ- 

 ence, and they have been wonderfully suc- 

 cessful. 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. 



The chief features of the Karst (lime- 

 stone) 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 swal- 

 low 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 oc- 

 cur in a limited space. They may be dish, 

 funnel, or well shaped, or of other forms. 

 Besides the simple basins, the dolinen also oc- 

 cur in the form of chimneys communicating 

 below with blind cavities or with under- 

 ground river courses or systems of fissures. 

 The first are known in France as avens, and 

 the second in Jamaica as H</7it holes. 



In 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 pu- 

 pils are mostly farmers' sons, and twenty- 

 three States and foreign countries are rep- 

 resented 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 solu- 

 tion of practical problems in mathematics. 

 A three years' course is prescribed. 



