Revietos — Prof. E. C. Lewis — Genesis of the Diamond. 367 



suppose, whilst in many respects the old quarrying system afforded 

 more facilities for observation than underground mining. 



Two papers were read before the British Association in 1886 and 

 1887 respectively, and abstracts of these were published. Hence. 

 Sections I and II of the present work, representing those papers, are 

 not wholly original ; and, indeed, Lewis' conclusions have been 

 quoted, notably by Mr. Sawyer, the Government Inspector of Mines, 

 and possibly by other writers on the diamond-mines of South 

 Africa. The history of a rock somewhat similar to that prevailing 

 in the Kimberley pipes, which has been found at two localities in 

 the United States, constitutes Section III of this posthumous 

 publication. 



The MSS. of these three papers ultimately came into the hands of 

 Professor Bonney, who, at the request of Mrs. Carvill Lewis, has 

 kindly undertaken to edit the whole. The two first papers are 

 printed very nearly as they were left by Professor Lewis. The 

 statements made and the results given represent his views in 1887, 

 and, so far as the editor knows, at the time of his death (July, 

 1888). Of the third paper (Section III) nothing had been written, 

 the materials consisted only of some very brief "jottings " and 

 a small set of rock-specimens. The editor has drawn up a state- 

 ment of the facts concerning them from such literature as he has 

 found, adding brief descriptions of the structures of the specimens 

 themselves. Some other material remained, from which data two 

 additional sections were compiled, but it was finally decided to 

 cancel them. In these (note, p. 68) the author insists on the 

 intimate connection of peridotite (or serpentine) with the diamond 

 at least in South Africa, and also in Kentucky, 



Our readers will easily understand the fascination which such 

 a subject as the diamond-rock of South Africa would have for a man 

 of Professor Lewis' stamp. Truly, it is a rock sui generis, and the 

 scientific interest attaching to it is only exceeded by its commercial 

 value. The author, in quoting previous writers, does no more than 

 justice to Mr. Dunn, who, as long ago as 1873, when many foolish 

 speculations were in vogue, insisted on the " euphotide (?)," as he 

 called it, being the mother rocJc of the diamond. 



It may be that there was a little confusion at the time of Lewis' 

 writing (1886-7), between the rock described in Section I and that 

 described in Section II, the one without diamonds, the other 

 diamantiferous. Nothing can be more certain than that the real 

 diamond-carrying rock of the Kimberley district is a medlej^ or 

 mixture, and in that case is scarcely entitled to a specific name, 

 such as "Kimberlite," bestowed by the author. " Kimberlite 

 proper," he tells us subsequently (p. 51), "is a typical porphyritic 

 lava " ; yes, but without diamonds. This, we apprehend, is the 

 rock described in Section I as " Hard Wack Floating Eeef," and 

 is the same rock as that familiarly known as the " snake " of 

 De Beers mine, a winding dyke of igneous rock varying in width, 

 which Mr. Williams, the General Manager of the De Beers Company, 

 supposes to be a younger eruptive formation coming from the same 



