Page:Popular Science Monthly Volume 49.djvu/291

Rh A valuable series of archæological investigations is chronicled in a tasteful 8vo entitled The Hill Caves of Yucatan The author, who is Curator of the Museum of American and Prehistoric Archæology at the University of Pennsylvania, had had his eye, so to speak, on the Central American hill caves for several years. The expedition was at last made possible by the munificence of Mr. J. W. Cor with, of Chicago, its purpose being to search for new evidence of man's antiquity in the caves of Central America. The party landed at Progreso, and rapidly made their way into the interior. The coralline and porous Mesozoic limestone of that part of Yucatan had not been upheaved or faulted, and, save for the waves of the hill ridges, lay as it was deposited. The caves were found to open vertically down into the ground like wells, the shaft having evidently been formed by the natural weathering down of a level rock surface until a hole in the roof of the cave was produced. These caves, of which a number were examined, were found in some cases to contain rude inscriptions on the walls, in all cases a large number of broken potsherds, and in the excavations conducted in the layers of rubbish which made up the floor of the caverns, charcoal and ashes, mixed with potsherds of many makes and some bones, but no arrowheads, spear points, or even flakes of hornstone. Some human bones scattered in the rubbish indicated that the old inhabitants of Yucatan practiced cannibalism. Taken as a whole, the antiquities show us the ancient cave visitor as an agriculturist rather than a hunter, although he seems not to have possessed domestic animals. The author, in closing, says: "An earlier people visiting Yucatan under its present topographical conditions must needs have left traces in the caves; because the undisturbed earth beneath the culture layer discovered always failed to show trace of any deeper, older, or more primitive human visitor, the conclusion was that no such earlier people had seen the region while its stony hills, its torrid plain, and its damp caves were as they now are." The book, aside from its archæological value, is of interest as giving a picture of the geography and people of that portion of Yucatan. It is very well illustrated.

One of the most beneficent services rendered by modern science consists in supplying a basis of exact knowledge for those necessary arts that have been carried on by empiric methods for centuries. Among the most ancient of these arts is that of utilizing the milk of our flocks and herds, for which a scientific basis has only recently become available. It is the purpose of the book before us to give the chemistry and bacteriology of the several processes of the dairy. The author first describes briefly the cow's udder and its process of secretion, and then passes to the composition of milk, giving the percentage composition of the milk of a number of animals, with a discussion of the variations observed, and a table of the legal standards in England and many of the United States. After setting forth some of the causes that influence the yield and quality of milk, he passes to the subject on which science has been able to give the most practical knowledge to the dairyman—bacteria. It is bacteria that cause milk to become ropy or viscous to turn blue, red, or yellow, to acquire a bitter taste, and to undergo fermentative curdling. Bacteria also are indispensable in the making of butter and cheese. Pure cultures of these organisms are used in dairies all over the north of Europe for ripening cream, and our author urges his fellow-countrymen not to be behind the foreigner in this matter. After discussing the essential features of the formation of butter and cheese, including the process of churning and the action of rennet, he gives the usual modes of testing milk, and closes with a chapter on milk as a food.

Convinced that throughout Europe there must have existed systems of picture writing such as survive among primitive races, Mr. Arthur J. Evans, the keeper of the Ashmolean Museum, has made extended explorations in Crete which have brought to light