26 



NA rURE 



[May 12, 1904 



posal works, and the town of Sheerness has taken a 

 still bolder departure in the application of such steam 

 to work pumps supplying the town with water. 

 This latter scheme was carried out by the author him- 

 self, and he is thus able to give full details as to the 

 economical results of this installation ; the first six 

 months' working showed a saving of nearly 500?., 

 equal to a reduction of 3d. per \\. in the town rates. 

 The comparative advantages of steam jet blowers and 

 fans are contrasted, and Mr. Goodrich clearly leans 

 towards the former as the more economical in the long 

 run ; in this connection he lays great stress upon the 

 absolute necessit}' of systematic tests of the waste gases 

 in order to determine whether or not combustion is 

 going on under the most economical conditions ; a 

 diagram given on p. 157 shows how serious the heat 

 losses may be if excess air is used. 



The second half of the book is devoted to a descrip- 

 tion of all the refuse destructors which have been put 

 to work in Great Britain and abroad up to the present 

 time. The date of the installation, the type and make 

 of destructor, the number of cells, the number and 

 type of boilers, height of chimney, the type of draught 

 used, the purpose for which the power is used, the 

 weight of the refuse destroyed daily, and the labour 

 cost per ton of refuse destroyed are all given. Most 

 complete information in regard to this important sub- 

 ject has thus been brought together, and there can be 

 no doubt that it will prove a most useful reference 

 volume to those engaged in planning such plants, 

 and to municipal authorities who are consider- 

 ing the desirability of erecting destructors. Up to the 

 present the various details and results given by Mr. 

 Goodrich have been scattered through the Proceedings 

 of one or two of our engineering societies, or embodied 

 in the reports of borough engineers, and it can have 

 been no light task to gather together the mass of in- 

 formation in this book. We have no hesitation in say- 

 ing that it will be a standard book of reference for 

 several years to come, and it is in a form in which it 

 will be comparatively easy, in the re-issue of fresh 

 editions from time to time, to keep it up to date. 



T. H. B. 



GEMS AND PRECIOUS STONES. 



Precious Stones, a Popuhn Account of tlicie 

 Characters, Occurrence and Applications, with an 

 Introduction to their Determination, for Mineral- 

 ogists, Lapidaries, Jeivellers. <l^-c., with an 

 Appendix on Pearls and Coral. By Prof. Max 

 Bauer. Translated from the German, with addi- 

 tions by L. J. Spencer. Pp. 627; with 20 plates and 

 94 tigures in the text. (London : Charles Griftin and 

 Go., Ltd., 1904.) Price 42,s. net. 



Gems and Gem Minerals. By Dr. Oliver Cummings 

 Farrington. Pp. 229; with 16 coloured plates and 

 Ua half-tone and line engravings. (Chicago : A. W. 

 .Mumford, 1903.) 



THL publication in 1890 by the Scientific Publishing 

 Company of New York of Dr. G. F. Kunz's 

 valuable " Gems and Precious Stones of North 

 .Xmerica " showed for the first time the possibility of 

 NO. 1802, VOL. 70] 



producing, by modern methods of photolithography, 

 illustrations of gems, either cut or uncut, which would 

 give some idea of their characteristic colour, trans- 

 parency and" lustre. The two works of which the 

 titles appear above have adopted the same methods of 

 illustration, and the plates are scarcely inferior in 

 beauty and in fidelity to the originals to those which 

 adorn Dr. Kunz's well known book. 



Prof. Max Bauer's " Edelsteinkunde " was issued 

 in parts in 1895 and 1S96, and at once took a foremost 

 place in scientific literature as the standard work on 

 all subjects relating to gems. It deals not only with 

 the methods adopted by mineralogists and others for 

 determining the mineral species to which gem stones 

 must be referred, but with such questions as their 

 artificial production, counterfeiting of gems, and their 

 alteration by heating, &c. — questions upon which it is 

 often very difficult to obtain satisfactory and trust- 

 worthy information. While mainly devoted to gems 

 viewed from the scientific standpoint, much valuable 

 information is added on the cutting, mounting and 

 price of gems, while the accounts of the localities and 

 mode of their occurrence are exceptionally full and 

 complete, the descriptions being illustrated by sketch- 

 maps and plans of workings. The coloured plates 

 give some idea of the brilliancy and exquisite beauty 

 of the original objects, whether these be crystals in 

 their matrix or cut stones. They are scarcely, if at 

 all, inferior in these respects to those in the work of 

 Dr. Kunz already referred to, and higher praise than 

 this can scarcely be given. 



Mr. Spencer has been well advised in undertaking 

 the translation-, with the aid of his wife, of this im- 

 portant standard work. But the book as it now 

 appears in English dress is much more than a mere 

 translation. Mr. Spencer's familiarity with the biblio- 

 graphv of mineralogy is well known, and he brings to 

 his task, in addition, wide knowledge and experience 

 gained in connection with his work in the splendid 

 national collection of minerals at South Kensington. 

 The author of the work has supplied references to the 

 more important papers which have been issued since 

 the first appearance of the book, and these with many 

 other works, including the valuable annual reports on 

 the production of gem stones by the L'nited States 

 Geological Survey, have been consulted by the trans- 

 lator, many new and valuable facts being added. It 

 would be easy to show, however, that even during the 

 decade that has not quite elapsed since the book was 

 written, much new information has accumulated on 

 man}- of the subjects dealt with, and to incorporate this, 

 as the translator points out in the case of the diamond, 

 so as to bring the matter quite up to date, would 

 involve the complete re-writing of whole sections. 

 The work is, nevertheless, so complete, trustworthy 

 and up to date that no better guide to the study of 

 gems can be indicated to the student, the worker, or 

 the dealer in these interesting objects. 



The general account of precious stones occupies no 

 pages, and, as the translator admits, would have to 

 be considerably enlarged if full justice were done to 

 the optical methods of discriminating the mineral 

 species. This, however, would have only a limited 



