1869.] Physics. 315 



had written. The difficulty of doing this we fully admit, and its 

 danger. Many of the chapters must have been entirely re-written ; 

 and then, indeed, the work would have been no longer a translation 

 of Simonin's, but the production of the English geologist, founded 

 on the idea of the French mining; engineer. 



No one desiring an account of all the mining countries of the 

 world, and of the methods by which the exploration of mines are 

 carried out, can find in any one volume so much instruction on 

 these points as in this one. Commencing with coal-mining, M. 

 Simonm proceeds to the consideration of metalliferous mining; 

 and follows this by descriptions of the processes of washing for gold, 

 the search for gems, &c. ; each division of the subject being treated 

 with considerable detail — as to methods of working, statistics of pro- 

 duction, and the like. For the latter, the author is under considerable 

 obligations to 'The Mineral Statistics of the United Kingdom.' 



The whole is most amply illustrated, and the chromo-lithographic 

 plates of the minerals are beautifully executed. We have never seen 

 anything of the kind to equal them. The new maps of the mining 

 fields of all countries, which have been executed especially for this 

 work by Mr. James Jordan, are of peculiar excellence, and give a 

 very high character to this essentially popular book on mining. 



' Industrie Minerale de la Province d'Hainaidt,' a report 

 by Mr. F. Jocham, the Director of Mines in that province, gives a 

 very full account of the process of coal-mining. From tliis report 

 we learn that the production of coal in Belgium lias been falling olf, 

 as will be seen by reference to our Chronicles of Mining. 



The returns for 1868 have not yet been completed. The 

 falling ofi" is attributed to the depressed state of trade and manu- 

 facture; and the Belgian coal-owners look hopefully to the future. 

 Another book of considerable value is 'Etude sur la Honille clu 

 bassin de Liege,' by Leon Jacques. In this work a very detailed 

 description of the collieries of this division of the Belgian coal- 

 fields is given. 



' On the Haulage of Coal' — being the report of the Committee 

 appointed by the North of England Institute of Mining Engineers 

 to investigate this subject, — which has just been published at New- 

 castle-on-Tyne. This is a work of pure experimental detail, of the 

 utmost value to all who are concerned in raisinc: coal. 



11. PHYSICS. 



Light.— M. Janssen has forwarded a letter from Simla (Himalaya) 

 to the French Academy of Sciences, in which, after giving further 

 particulars respecting his discovery of the visibihty of the spectra of 



