go2 
Societies and Academies. 
; Lonpon. 
Royal Microscopical Society (Industrial Applica- 
tions Section), May 30.—Dr. A. Hutchinson in the 
chair—H. B. Milner: The microscopical investiga- 
tion of sands for various industrial purposes. The 
application of the petrological microscope to the 
discrimination of sands and allied rocks suited to 
various industrial requirements, such as glass manu- 
facture, abrasives, ferrous and non-ferrous foundry 
work, silica-brick production, cement, mortar, con- 
crete, brick and tile manufacture, and as a source 
of economically valuable minerals such as monazite 
and thorianite for incandescent gas mantles, etc., 
was discussed. The distinctive properties of sands 
for their proper utilisation in the arts can be deter- 
mined by the microscope. The employment of the 
microscope should not be interpreted as a certain 
cure for all technical difficulties, but the full possi- 
bilities of the instrument are still unappreciated by 
the majority of manufacturers who employed re- 
fractory materials. Lines of microscopical research 
on refractory sands, particularly in connexion with 
silica-bricks, were suggested. 
Aristotelian Society, June 4.—Prof. A. N. White- 
head, president, in the chair.—Sir Leslie Mackenzie : 
What does Dr. Whitehead mean by “‘ event”? The 
word has a peculiar importance in his theory. It is 
intended to cover the fact that, on whatever theory 
we finally decide as to the nature of the physical 
world, that world cannot now be described or even 
discussed except abstractly if we confine ourselves to 
terms of space alone; for space and time have a 
common root, and, if we speak in terms of space 
alone, we can properly do so only in one of two ways : 
either we must use space as meaning space-time or 
simply as a second grade of abstraction. In either 
case it omits the essential point that the physical 
world is to be taken in terms of space and time in 
unity. At first sight, the word ‘‘ event’’ seems to 
overstress the time element. The fact of a happen- 
ing is thought of first in terms of time and not in 
terms of space. But it is something perceptible that 
happens, and if it took no time to happen, it would 
not be perceptible ; for it would be nothing at all. 
Time, therefore, is of the essence of every happening. 
But equally there is no doubt that what happens 
physically happens in a space, it happens some- 
where, and every physical happening must be thought 
of as also in space. Whether explicitly so under- 
stood or not, every event in the physical world is, 
therefore, a thing to be thought of as involving both 
time and space. 
Geological Society, June 6.—Prof. W. W. Watts, 
vice-president, in the chair—H. Bolton: On a new 
blattoid wing from the Harrow Hill mine, Drybrook 
(Forest of Dean). The wing is a right fore-wing 
of a new genus of blattoid, and of unusual size. 
The surface is densely chitinous, and crossed by a 
series of powerful well-branched veins, the cubitus 
being especially well developed, and much unlike 
any other known among the Coal-Measure blattoids. 
The insect probably occupied an intermediate 
position between the families Archimylacride and 
Hemimylacride.—C. E. Tilley: Contact - meta- 
morphism in the Comrie area of the Perthshire 
Highlands. 
diorite-complex is divisible into (a) zone of biotite 
and (b) zone of cordierite, which rapidly passes into 
a zone of true hornfelses. In the Aberfoyle-Slate 
band, an additional outer zone (zone of spotted 
slates) is found; but no chemical reconstruction 
NO. 2800, VOL. 111] 
NATURE 
The thermal aureole of the Cairn Chois | 

[JUNE 30, 1923 
is apparent. The progression of metamorphism as 
here observed is that distinctive of kaolin-free slates 
subject to thermal alteration. The rocks of the 
hornfels zone—with a minimum width of 150 yards— 
show a wide range of composition. A classification 
of the silica-poor hornfelses is suggested, starting 
from a simplified system of fout components. The 
mineralogical assemblages thus ideally determined 
can be alternatively developed from a consideration 
of the chemical changes incident on metamorphism 
of sericite-chlorite-quartz assemblages of the original 
rocks. Certain abnormal assemblages are considered 
as unstable. These, while not invalidating the 
hornfels classification adopted, serve to indicate 
that equilibrium in the inner contact-zone is closely 
approached rather than completely attained. 
Linnean Society, June 7.—Dr. A. B. Rendle, 
president, in the chair—H. Sandon: Some Protozoa 
from the soils and mosses of Spitsbergen obtained 
by the Oxford University Expedition——J. D. F. 
Gilchrist: A form of dimorphism and asexual repro- 
duction in Ptychodera capensis. C. E. Moss: The 
species and forms of Salicornia in South Africa,— 
J. Burtt-Davy: Geographical distribution of some 
Transvaal Leguminose. The Leguminose form the 
largest family of Transvaal Spermatophyta, as 
regards numbers of species, having about 100 species 
more than the Composite, and comprising hearly 
10 per cent. of the recorded species of the flora. 
A large number of the genera have very few species. 
The greatest number of endemics generally occur 
in genera with the greatest number of species; and 
the species show great variation in range. Even in 
the samie genus some range almost the length of the 
Continent. Classified according to their geographical 
range of distribution, the Papilionacez fall into 
five very distinct groups: (1) the South-western 
Cape Province element, (2) the Kalahari element, 
(3) the Rain-forest element of the eastern high 
mountains, (4) the Tropical African element, and 
(5) the Warm Temperate Plateau element. (4) and 
(5) account for 94 per cent. (306 species) of the total 
Papilionaceous flora and 123 are endemic to the 
Transvaal. Adding to these species those which 
range into the states bordering on the Transvaal 
but not beyond them, the number of endemics 
forms 78 per cent. of the population. Fifteen species 
(less than 5 per cent.) are common to the Transvaal 
and India, and five species are found in Madagascar. 
In connexion with the view that arborescent forms 
are the older types, it is noteworthy that, with one 
exception, possibly introduced, the arborescent and 
shrubby species of Papilionaceze (only about twenty 
in all) belong to the Tropical African element, and 
about half of them belong to genera with few species. 
—C. E. Moss: Velaminous roots in terrestrial 
orchids. They are especially noticeable in the orchid 
genus Eulophia, abundant at the Cape (S.A.). 
Physical Society, June 8.—Dr. Alexander Russell 
in the chair.—J. G. Gray: A general solution of 
the problem of finding the true vertical for all types 
of marine and aerial craft. The difficulties presented 
by this problem arise from the horizontal accelera- 
tions which result from the turning of vehicles. 
A gyroscopic pendulum to succeed must possess a 
real precessional period, or a virtual precessional 
period during turning motion of the vehicle on which 
it is mounted, which is measured in hours. Pioneer 
forms of Gray stabiliser comprise a single gyroscope, 
mounted with its axis normally vertical, and an 
erector connected rigidly to it; the whole is pivoted 
to a gimbal frame by means of two cross pivots. 
One form of erector consists of a circular track 
carried by the pivoted system, and so arranged’ 

