JANUARY 10, 1907 | 
NALURE 
other writers, and Prof. Beck remarks that, since the 
aqueous solutions in the fissures cooled very slowly, and 
“their great liquidity was extremely favourable to diffusion 
of the dissolved substances, crystals of large size are fre- 
quently found in pegmatites.’’? While thermal waters found 
their way to upper parts of the crust, the solutions that 
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resulted in pegmatite-veins represent material retained at | 
considerable depths. 
Hence ore-deposits associated with | 
pegmatites become exposed only after long ages of denuda- | 
tion. Prof. Becls cites several examples where tin, copper, 
| through the working 
and gold are among the substances deposited in connec- | 
tion with pegmatites. 
Dr. G. B. Trener (Verhandlungen der k.k. 
Reichsanstalt, 1905, pp. 366 and 372) is conducting experi- 
ments to show that metals undergo diffusion in solid 
crystalline rocks at temperatures far below the melting 
points of the metals employed. The complete results are 
to be published in the Jahrbuch of the Reichsanstalt as 
a chapter of the description of the Cima d’Asta, but the 
preliminary announcements have already aroused discussion. 
Among the curious points raised by Dr. Trener, is the 
resistance of mica to diffusion of metals in a direction 
perpendicular to its cleavage planes; well-developed mica- 
schists may thus be practically impenetrable when their 
| duces the descriptions 
geol. | 
under the guidance of Mr. Kynaston, would certainly 
suggest that they were igneous intrusions of an extremely 
basic type. 
Mr. A. L. Hall (p. 41) describes the fine country between 
Lydenburg and the Devil’s Kantoor, or Devil’s Shop, so- 
called from the fantastic weathering of the sandston 
masses near the edge of the great escarpment.  Gold- 
mining is carried on in this hilly region, and a lime 
industry has sprung up near Godwan River Station 
of secondary deposits of calcite in 
Mr. Hall, we think wisely, intro- 
of the microscopic characters of his 
rocks, as explanations of their structure, side by side with 
the account of their features in the field. A rock believed 
to be a tuff is interestingly recorded (p. 53) among the 
otherwise intrusive igneous masses found in the Transvaal 
system. The fine illustrations to the report show the 
escarpment of the Kantoor quartzite, with the rapid 
descent towards the old granite on the east; the gorge in 
the far younger quartzite of the Pretoria series, between 
Waterval Boven and Waterval Onder, where the traveller 
from the monotonous plateau of the Transvaal welcomes 
the picturesque notching of its edge; and other scenes 
from this noble region, including the weathered quartzite 
(Fig. 1) of the Kantoor itself. 
the dolomitic series. 
Fic. 2.—Eart .-pillars, soutn of Alkmaar, Transvaal. 
foliation-planes are to the direction of 
diffusion. : 
The Report of the Geological Survey of the Transvaal 
for 1904 has been noticed already in Nature (vol. Ixxiv., 
p- 646). The volume for 1905 has now been issued, dated 
August, 1906, liberally illustrated with plates and coloured 
geological maps and sections, and at the same moderate 
price of 7s. 6d. The director, Mr. H. Kynaston, describes 
a recent survey of the Komati Poort coalfield, which is 
conveniently situated on the Delagoa Bay side of the 
country. He reminds us of the record of 25 feet of coal 
in 33 feet of strata passed through by a bore-hole near 
Tenbosch Station in 1903, and remarks that this massive 
seam may underlie the smaller ones that haye been proved 
at various points. Arguments are given to show that the 
horizon of these coal-bearing beds, and those of the Trans- 
vaal generally, may be in the Beaufort series, and not in 
the underlying Ecca series, as has been generally supposed 
(p. 25). Mr. Kynaston also describes a Coal-measure series 
(p- 35) in the Bushveld area west of the Pietersburg rail- 
way. The igneous rocks of this region present many 
points of interest, especially in the occurrence of bands 
of magnetite, resembling dykes, associated with, but not 
passing into, a considerable mass of norite. Similar bands 
are well dealt with by Mr. Hall in a later paper in this 
report (p. 73). Our field-inspection of these iron ores, 
NO. 1941, VOL 75] 
perpendicular 
Another photographic _ illustration 
(Fig. 2) shows the detrital sand re- 
sulting from the weathering of the 
older granite, which is now eaten 
out into pillars as much as 25 feet 
high, with sometimes a cake of 
more resisting rock upon the top. 
Passing over other papers in this 
report, as unfortunately must be the 
case in a general notice, we may 
mention Mr. Mellor’s account of the 
Witbank Coalfield near Middleburg 
on the main plateau (p. 81). The 
Permian glacial conglomerate has 
here supplied, during an epoch of 
denudation, much of the material of 
the overlying Beaufort (?) Coal- 
measures. The coal-seams, one of 
them being 24 feet thick, are de- 
scribed and illustrated by sections 
(p. 97, &c.). The presence of fine 
muddy layers raises the ash, even in 
some of the workable coal, to 17 per 
cent., and the ash rarely falls below 
7 per cent. 
Mr. Tweddill (p. 106), in a hand- 
somely illustrated paper, describes 
some ruby-bearing rocks from the 
Leydsdorp district, notably a beautiful 
example consisting of a pale pyroxene, kyanite, and finely 
granular ruby. He holds out hopes, if we read him rightly, 
that ruby may be in time discovered on a scale of com- 
mercial importance in the Transvaal. GAC enc: 
MEN OF SCIENCE IN AMERICA. 
“HE issue of Science for November 23 contains an 
article by Prof. McKeen Cattell on the selection, and 
arrangement in order of merit, of a thousand American 
men of science. A table was compiled from lists of 
fellows of societies, biographical dictionaries, ‘* Who’s 
Who,’’ &c., of the numbers of persons engaged in each 
branch of science. It appears that chemists are the most 
numerous, in America at all events, forming 164 per 1000 
of all scientific men, zoologists coming a close second 
with 155 per 1000. Anthropologists stand at the foot of the 
list with only twenty-three, but neither statisticians nor 
economists, it would seem, were taken into account. Ten 
leading representatives of each science were then asked to 
arrange in order of merit a certain number of students of 
that science, the numbers fixed being roughly proportionate 
to the totals in the table first compiled. The positions 
assigned by the different judges to every individual were 
averaged, and the probable error of the average posi- 
