Reviews — J. Murdoch — Opaque Minerals. 425 



III. — Glastonbury Lake- Village. 



. f |THE second volume of Messrs. Bulleid & Gray's report on the 

 JL Glastonbury Lake- Village is just published. It is most 

 valuable, and reflects the highest credit on the authors. This 

 volume contains much matter of geological interest in addition to 

 the archaeology. There are reports on the plants by Clement Reid, 

 on the bird remains by C. W. Andrews, on the wild and domestic 

 mammalia by W. B. Dawkins & J. W. Jackson, and on the humans 

 by "W. B. Dawkins. The illustrations are profuse and excellent, 

 and the report as a whole is as complete an account of such a site as 

 has yet been made available. 



Among the vertebrates the bird Pelecanus erispus is the most 

 interesting, for although remains have been previously found in the 

 Pens, Dr. Andrews has examined portions of five individuals and 

 many fragments from Glastonbury, clearly indicating that the birds 

 bred in the neighbourhood, and possibly pointing to a source of food 

 for the inhabitants. The report closes with an exhaustive index, 

 most wisely provided, which greatly enhances its value. 



BEVIE"W"S. 



I, — Microscopical Determination of the Opaque Minerals. By 

 Joseph Mdrpoch. pp. viii + 165, with 9 figures in the text and 

 1 coloured plate. New York, John Wiley & Sons, Inc. ; 

 London, Chapman & Hall, Ltd., 1916. Price 9s. 6d. net. 



WHY the microscope, while holding so predominant a position in 

 the determination of rocks by means of the characters 

 revealed in a thin slice and in the study of transparent substances 

 generally, has hitherto been so little used in the study of metals and 

 alloys and in the identification of opaque substances, is perhaps not 

 difficult to understand. It is not at first sight by any means obvious 

 that this instrument is at all suitable for the purpose, and so vast 

 was the vista opened out by the application of the microscopical 

 method to penological work that the equally important field of 

 research lying fallow in the case of opaque substances for a long 

 time almost entirely escaped notice. It was, in fact, not till the 

 discovery of different kinds of hardened steels and the consequent 

 necessity for determining and explaining their various characteristics 

 that metallurgists began to pay general attention to the microscopic 

 study of polished sections. Yet more than half a century has 

 elapsed since the gifted Sorby, to whom we are likewise indebted 

 for drawing general attention to the advantage of the microscopic 

 study of thin slices of rocks, had made use of practically all the 

 devices in vogue among metallurgists of to-day; while it is only 

 within the past four or five years that anything like a systematic 

 study of the opaque minerals has been attempted. Mr. Murdoch's 

 book marks the beginning of a new epoch. Previous writers and 

 workers had confined their attention to some particular mineral 

 group or some isolated problem. He is the first to make a systematic 

 study of the opaque minerals, and above all to think out and develop 



