SEPTEMBER 17, 1897.] 
vill Lewis, edited by his friend, Professor T. G. 
Bonney, of London.* 
It will be remembered that Professor Lewis 
was the first to present a clear and definite theory 
of the origin of the South African diamonds, as 
resulting from the intrusion of igneous rocks into 
and through carbonaceous shales, and the crys- 
tallization of the carbon throughout the rock as 
it cooled, from hydrocarbons distilled from the 
shale that had been broken through. These 
views, now for the most part accepted, and sub- 
sequently confirmed by other and very interest- 
ing parallel discoveries, he presented in two 
papers read before the British Association for 
the Advancement of Science at its meetings held 
in 1886, at Birmingham, and in 1887, at Man- 
chester. Before he was able, however, to pre- 
pare them for publication and carry them to the 
greater completeness that he desired, Professor 
Lewis succumbed to an attack of typhoid fever, 
which removed one of the most brilliant and 
capable of the rising scientists of this country. 
Agreeably to his expressed wishes, his material 
was entrusted to his friend and co-laborer, Pro- 
fessor George H. Williams, of Johns Hopkins 
University ; but, by a strange fatality, before 
the latter had time to arrange and edit these 
papers this distinguished scientist also fell a vic- 
tim to the same disease, in 1894. The work was 
then committed to Professor Bonney and is at 
last given to the scientific world. 
’ The book consists of an introductory note by 
Mrs. Lewis ; a preface by Professor Bonney ; the 
two papers of Professor Lewis himself, with 
some later notices and references by the editor ; 
a brief account of similar material from other 
localities, belonging to Professor Lewis—also by 
the editor; a closing note on some other MSS. 
of Professor Lewis, and a full index. There 
are also two plates and a number of smaller il- 
lustrations, the latter from Professor Lewis’ own 
drawings. 
* Papers and notes on the ‘Genesis and Matrix of 
the Diamond.’ By the late Henry Carvill Lewis, 
M.A., F.G.S., Professor of Mineralogy in the Acad- 
emy of Natural Sciences, Philadelphia, Professor of 
Geology in Haverford College, U.S.A. Pages xvi+ 
72. 2 Plates. Edited from his unpublished MSS., 
by Professor T. G. Bonney, D.Sc. LL.D., F.R.S., &e. 
Longmans, Green & Co., Londonand Bombay. 1897. 
SCIENCE. 
451 
The first paper, ‘On a diamond-bearing peri- 
dotite and on the history of the diamond’ (1886), 
is brief, dealing with the general character and 
occurrence of the diamantiferous rock at Kim- 
berley, and outlining Professor Lewis’ theory. 
The second paper, ‘The matrix of the 
diamond” (1887), is more extended and goes 
into an exhaustive discussion and comparison of 
the various aspects, contents and alterations of 
the rock, which he finds to be different from any 
previously described, and, therefore, proposes 
for it the name of Kimberlite. Its main charac- 
ter is that of a highly basic porphyritic perido- 
tite, filled with olivine crystals and grains, more 
or less altered, and various other minerals— 
serpentine, tremolite, etc., with bronzite, rutile, 
perovskite, pyrope garnets, micaceous minerals 
and other forms, and at times brecciated in 
structure, filled with fragments of carbonaceous 
shale brought up from below. The shales are 
of Triassic age, the ‘Karoo beds’ of that 
region, and the intrusion of the peridotite in 
the great ‘pipes’ or chimneys that constitute 
the mines is therefore proved to be of a later, 
though not exactly determined period. 
The question has sometimes been raised 
whether the diamonds themselves may not have 
been carried up from a deeper source in rocks 
below, instead of originating in the peridotite ; 
and the occurrence of broken crystals has been 
cited in support of this view. Professor Lewis, 
however, disposes very completely of this idea 
in two ways: He refers to the well-known fact 
that each of the great mines or ‘pipes’ yields 
diamonds that have, in some respects, a type of 
character peculiar to that oneand different from 
the others, so that African experts, and even 
those who have never been there, can recognize 
from which mine any diamond has come. 
Further, as to the broken crystals, he shows 
that breakage not unfrequently occurs after the 
diamonds are removed from the rock, and 
points out that this is a result of strain in their 
formation, as indicated by microscopical and 
optical examination, and that such a condition 
is known to produce ruptures and explosions in 
other minerals. It may be added here, al- 
though Professor Lewis does not speak of it, 
that many crystals must be broken in the blast- 
ing of the rock, the shoveling and the carting 
