DECEMBER 3, 1993 | 
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NATURE 
119 
its appropriate tube. The readings are taken by setting a 
pair of needle-points just to touch the liquid surface, and 
then measuring how they differ in level by micrometer 
screws, or by callipering suitable jaws. The instrument is 
trustworthy to oor mm. of water-pressure. (4) A_multi- 
plying pressure-gauge in which the motion of a float or 
ball is used to operate a finger moving round a dial. The 
dial is divided in such a manner that the square roots of 
the pressure-differences are read off. Air velocities are 
therefore given directly. 
Geological Society, November 4.—Sir Archibald Geikie, 
F.R.S., vice-president, in the chair.—Metamorphism in the 
Loch-Lomond district, by Mr. E. Hubert Cunningham- 
Craig. The area dealt with includes all the Highland rocks 
on either side of the loch, as well as the area lying to the 
eastward. Each stage of the progressive metamorphism 
can be studied without confusing its effects with those of 
another process. The rocks from the Leny-Grit group and 
the Aberfoil-Slate group show dynamic metamorphism, and 
at Rudha Mor the beginning of the thermal type is seen. 
This is superseded by a constructive metamorphism, prob- 
ably of hydrothermal type, and the rocks become more 
highly crystalline, until all clastic structures are obliterated. 
The segregation of like minerals into folia, the total re- 
crystallisation, and the genesis of new mineral-groupings, 
result in the production of coarsely-crystalline albite-gneisses 
from siliceous and felspathic grits.—On a new cave on the 
eastern side of Gibraltar, by Mr. H. D. Acland. This 
cave is situated south of the eastern end of the tunnel, which 
pierces the Rock from the dockyard on the western side to 
““ Monkeys’ Quarry’ on the eastern. The main hall is 
about 7o feet high and 45 feet wide, and has a smooth 
stalagmite floor resting on breccia, and a stalactitic roof 
covering the limestone of the Rock. Its floor falls to a 
point 19 feet above sea-level. The lower gallery descends 
at its far end to little short of sea-level. Its floor consists of 
stalagmite resting on calcareous sand; this on coarse sand, 
followed by rubbly and calcareous grit, which in time rests 
on the rock-floor at a depth of 15 feet. In the calcareous 
grit are well-rounded stones, some pierced by pholades. At 
a depth of 13 feet were echinids and barnacles. Two other 
galleries were explored, and in these the walls are pitted 
to a height of 28 feet above sea-level. The author con- 
cludes that the cave existed at first as a fissure, to which 
the sea obtained access for a long period, and during this 
period the rock was elevated some 42 feet. The cave was 
closed to the sea at a period geologically recent, and the 
breccia and sand-slopes date from a still more recent period. 
Linnean Society, November 5.—Prof. S. H. Vines, F.R.S., 
president, in the chair.—Dr. W. G. Ridewood exhibited 
the frontal bones of a horse showing rudimentary horns. 
The bony protuberances were about three inches apart, and 
were set upon the curved ridges that constituted the anterior 
margins of the areas of origin of the temporal muscles. In 
the natural sloping position of the head in the living horse 
they would have been vertically above the orbits. Dr. Ride- 
wood pointed out that the exceptional cases of horny bosses 
occurring in horses could hardly. be regarded as instances 
of reversion, for the paleontological record of the evolution 
of the horse is remarkably complete, and no indications 
of horns are to be found in the extinct congeners of the 
modern equines.—Prof. Weiss exhibited some preparations 
and photographs of a mycorhiza or mycorhizome from the 
Coal-measures. The preparations were in part from the 
Cash collection at the Owens College, Manchester, and in 
part from Dr. Scott’s private collection. They showed the 
existence in. a small root-like organ of fungal filaments 
presenting all the appearances of those found in the roots 
of many orchids and in the rhizome of Psilotum.—Mr. B. H. 
Bentley exhibited a large series of lantern-slides, designed 
for teaching purposes, which he had taken, illustrating 
certain types of floral pollination, and bees and other insects 
in actual operation—Mr. L. A. Boodle read a paper on 
the structure of leaves of the bracken, Pteris aquilina, in 
relation to environment. It is well known that in dry ex- 
posed situations the bracken produces leaves of a hard dwarf 
habit, while in very sheltered localities the leaves are quite 
soft. This difference in external characters is accompanied 
by a difference in structural characters. The exposed 
NO. 1779, VOL. 69] 
leaf has a hypoderm, and is a distinctly xerophytic ‘‘ sun- 
leaf ’’; the other type of leaf is a pronounced “ shade-leaf,’’ 
having no hypoderm, and weakly developed palisade-tissue 
or no definite palisade. A similar difference may occur in 
different leaves of the same plant, or in different parts of 
the same leaf when shelter and exposure are sufficiently 
localised. A slightly xerophytic plant, when transferred to 
a greenhouse, produced shade-leaves only (though the 
illumination was fairly strong), and in these leaves the 
indusia were considerably reduced. The bracken is thus very 
plastic in its relation to environment.—A paper by Mr. E. P. 
Stebbing, on the life-history of a new Monophlebus from 
India, with a note on that of a Vedalia predaceous upon 
it; with remarks on the Monophlebine of the Indian region, 
was, in the absence of the author, read for him by Mr. G. S. 
Saunders. Up to rgor only five species of the genus Mono- 
phlebus were known as Indian, and four of these were de- 
scribed from the male insect only; in that year the writer 
discovered both sexes of two new species, which had been 
named by Mr. E. Ernest Green, Government entomologist, 
Ceylon, Monophlebus Stebbingi and M. Dalbergae, whilst 
a third species, of which the females alone are known, was 
named M. Tectonae. These coccids infest forests in large 
numbers, and in consequence their ravages are serious. The 
amount of nutriment withdrawn from the trees is extra- 
ordinary, and the extruded sugary fluid may be heard falling 
like rain in an infested forest. The predaceous J’edalia 
Guerinii, Crotch, was then described, and its method of 
attack and great voracity; in turn, it is parasitised by a 
small fly whilst in the larval stage. 
Paris. — 
Academy of Sciences, November 25.—M. Albert Gaudry 
in the chair.—The relation between sun-spots and terrestrial 
magnetism. The utility of continual registration of the 
variable elements of the sun, by M. H. Deslandres. After 
a critical examination of the various hypotheses which have 
been put forward to connect solar phenomena with magnetic 
storms, the conclusion is arrived at that the solution 
of the problem has not yet been reached.—On the geo- 
logical significance of anomalies in gravity, by M. 
de Lapparent. It is generally accepted that gravity is 
in excess of the average in Oceanic regions, and is below 
the average on land. The suggestion is made, in opposi- 
tion to the views of M. Faye, that the observed anomalies 
are due rather to the effect of dislocation than of the low 
temperature of the ocean floor.—On the reinforcement of 
the action of the bundle of light rays upon the eye, when 
accompanied by the n-rays, by M. R. Blondiot. It has 
been shown in previous papers that a feebly illuminated 
object increases in brightness when the n-rays are allowed 
to fall on it. It has now been found that if the n-rays are 
directed towards the eye instead of the object, a similar 
reinforcement is  observed.—M. Emile Bertin was 
elected a member in the section of geography and 
navigation in the place of the late M. de Bussy.—On 
functional equations and the theory of divergent series, by 
M L. Fejer.—On a system of three functions of real 
variables, by M. Pompieu.—On the possibility of 
sustaining in the air an apparatus employing a helix, using 
an internal combustion motor, by M. Charles Renard. 
The reduction in the weight of an internal combustion 
motor per horse-power developed, now brought as low as 
2-5 kilograms per horse-power, renders possible the use 
of a light helix in an aérostat. The theory is given for 
the conditions necessary in practice.—On wie measurement 
of the effect of electric waves at a distance by means of 
the bolometer, by M. G. Tissot. The use of a bolometer 
as a detector has given readable results at a distance of 
| 40 kilometves. The most advantageous arranzement of the 
apparatus has been worked out experimentally.—On the 
colour of aqueous solutions of methyl orange and the change 
produced by acids, by M. P. Vaillant. Simultaneous 
observations of electrical conductivity and molecular absorp- 
tion (measured with the Gouy spectrophotometer) show that 
neither the theories of Ostwald nor of Kiister are completely 
in accord with fact.. The results point to a progressive 
molecular transformation of methyl orange under the action 
| of acids, the change being more rapid with the stronger 
acids.—The modes of deformation and fracture of iron and 
' mild steel, by MM. F. Osmond, Ch. Frémont, and G. 
