550 SCIENCE PROGRESS 



The fust part of the book deals with the optical properties of minerals, and is 

 undoubtedly the most lucid description of that fascinating subject which has yet 

 been written. The characters of minerals as seen in thin section under the micro- 

 scope are stated and explained in turn (i) in ordinary transmitted light, (2) in 

 reflected light, (3) with the lower nicol inserted, (4) with both nicols inserted, 

 and (5) with both nicols inserted in convergent light. Next follow detailed 

 descriptions of the chief rock-forming minerals, each of which is admirably illus- 

 trated by one or more photographs. There are also beautiful photographs of 

 interference figures, and a very successful reproduction in colour of Newton's 

 scale as exemplified by a quartz wedge between crossed nicols. Mr. Smith is to 

 be congratulated both on his skill as a photomicrographist and on his choice of 

 material. The book concludes with two sections dealing with the rapid deter- 

 mination of refractive indices, and with a short introduction to petrology. Al- 

 together we have nothing but praise for a wholly admirable book which will 

 lighten the task of many a student and demonstrator, and which ought to be in 

 the hands of all who are making their first acquaintance with microscopical 

 mineralogy and petrology. 



ANTHROPOLOGY 



Wookey Hole : Its Caves and Cave-dwellers. By Herbert E. Balch, 

 F.S.A. [Royal 4to, pp. xiv + 268, with 36 plates and 55 text-figures.] 

 (Oxford University Press, 1914. Price 25^. net.) 



The caves of the south-west of England, such as " Kent's Hole," Torquay, the 

 Cheddar Caves, and the so-called " King Arthur's Cave " on the Wye, have 

 been fruitful in relics of early man; and the small "Hyena Den" at Wookey 

 Hole itself, which was explored by Prof. Boyd Dawkins, was one of the first 

 caves in this country to be opened up scientifically. The great cave at Wookey 

 Hole, where the river Axe flows forth from its subterranean channel, two miles 

 from Wells, has long been famous, and has been regarded with superstitious 

 awe by the country-folk for centuries. In the seventeenth century certain 

 vandals destroyed much of the beauty of the cave by cutting down and carrying 

 away many of the stalactites which decorated the larger chambers. Yet, in 

 spite of this, it has remained for Mr. Balch to open up the inner recesses of 

 the immense cavern, and to reveal to us the most interesting story of an 

 ancient tribe who made their abode there. The great cave is only a few yards 

 from Boyd Dawkins' " Hyena Den," but the cave-dwellers, whom it is the 

 author's main purpose to describe, have no connection with the so-called " cave- 

 men " of the Late Pleistocene. They are a much more recent people who 

 inhabited the cave during the Prehistoric Iron Age and throughout the centuries 

 of the Roman occupation of Somersetshire, and who are obviously closely 

 related to the inhabitants of the neighbouring Lake Village at Glastonbury. 



Mr. Balch has been systematically exploring the caves for several years, and 

 much of the work has been of a laborious and even dangerous character, for 

 many of these old water-channels are very difficult of access. In particular, 

 the descent of a large and deep swallet which exists at Eastwater is evidently 

 a feat which only expert rock-climbers could have accomplished. The chief 

 work, however, was in excavating the floor of the great cave near its mouth, 

 where the rich accumulation of Iron-Age relics was found. Numerous pieces 

 of pottery, iron swords, saws, sickles, and other iron instruments, bronze imple- 



