58 The American Geologist. July, iw.7 
scripts by Prof. T. G. Bonney. Octavo, 7'2 and xvi pp., three plates. 
$2.50. Longmans. Green & Co., New York, 1897. This is the second of 
Prof. Lewis' works issued posthumously by Mrs. Lewie. It shows the 
versatility of Prof. Lewis' genius. It stands at that end of the science 
at which is required the greatest preliminary study and the most pa- 
tience and skill with delicate apparatus, as the other stood where the 
least is required. These two works attest the affectionate fidelity and 
remembrance of her whose close sympathy and aid must have been one 
of his chief incentives. 
To the original papers of Prof. Lewis, which he read before the Brit- 
ish Association for the Advancement of Science, Prof. Bonney has made 
valuable editorial minor emendations and has added brief macroscopic 
and microscopic descriptions of some specimens from America found 
amongst the materials left by Prof. Lewis. This friendly editorial ser- 
vice has been done by Prof. Bonney in lieu of Prof. G. H. Williams, to 
whom it was. entrusted by Prof. Lewis during his last illness, but who 
died from the same disease (typhoid fever) before he was able to accom- 
plish the charge. 
The remarkable rock containing the diamonds found at Kimberley, 
South Africa, was named kimberlyte by Prof. Lewis. He found it con- 
tained the following minerals, many of them only in microscopic quan- 
tities. 
Olivine, forming the larger portion of the rock, often quite fresh. 
Entitaiite, chroma diopside, svLCiraydite and bmtiie often in fine green 
plates or crystals. 
Biotite, a very prominent ingredient. 
Oarnet, common in bright red grains. 
Pei-ovakite, abundant in microscopic crystals. 
Magnetite, chromite, ilmenite, picoiite, common under the micro- 
scope. 
Apatite, epidote, orthite, tremotite,iourmali ne , rutile, spheiie, leucox- 
ene (scarce and minute). 
Serpentine, calcite, zeolites, chalcedony and talc as decomposition 
products. Also an undetermined mineral, probably cyanite, and finally 
diamond (scarce). 
The rock embraces many inclusions of rock-fragments, such as shale, 
diabase, granite, gneiss, eclogyte and of other rocks, but those of shale 
are by far the most numerous, sometimes constituting the greater por- 
tion of the rock. 
Kimberlyte is a decayed and brecciated peridotyte and exists in the 
crater and "pipe" of an extinct volcano, and is now mined at a depth of 
over 1500 feet. Its structure resembles the chondritic structure of stony 
meteorites, due, as supposed by Lewis, to frequent and continued ex- 
plosive jars during the activity of the volcano. The adjoining black 
shale is bituminous and charged with pyrite, but those fragments which 
are enclosed in the kimberlyte have lost their shaly character, their 
carbonaceous matter and their sulphur. It is to these shale fragments 
that Lewis attributes the origin of the diamond, through theconcentra- 
