
Marcu 18, 1915 | 
NATURE 
83 

when the valve closure begins to be finally accom- 
plished. The function of the muscular slips now de- 
scribed may be regarded as a double one—(a) to keep 
the flaps away from the ventricular walls, and thus to 
ensure the provision of an adequate space between 
the flap and the ventricular wall for the full develop- 
ment of the retro-valvular eddy, and (b) to afford by 
their contraction direct mechanical assistance in the 
raising of the flaps into the position of final closure. 
Geological Society, February 24.—Dr. A. Smith 
Woodward, president, in the chair.—Dr. J. E. 
Marr: The Ashgillian succession in the tract 
to the west of Coniston Lake. The author 
has studied in detail the succession of the 
Ashgillian strata in Ashgill Beck and the adjoining 
tract. An account of the lithological characters and 
lists of the fossil contents of the various divisions are 
given, and confirmatory sections from Coniston Vil- 
lage to Appletreeworth Beck are described. A com- 
parison is made with the beds of the Cautley district, 
previously described by the author. Some fossils 
which have not yet been found in the Lower Ash- 
gillian of the Cautley district occur in the beds of 
that division at Coniston. From a study of the 
fossils of the Coniston tract and of other areas in 
Britain and the Continent, it would appear that a 
twofold division of the Ashgillian strata which is of 
more than local value may be made. The lower 
division is characterised by the abundance of Phillip- 
sinella parabola, and the upper by the profusion of 
Phacops mucronatus.——H. S. Shelton: The radio- 
active methods of determining geological time. The 
author holds that the radio-active method of deter- 
mining geological time, while of great interest, is 
not of such certainty as to be independent of con- 
firmation from other lines of investigation. The 
various radio-active methods, helium ratios, lead 
ratios, and pleochroic haloes are severally examined, 
and the various sources of uncertainty, general and 
particular, are pointed out. The most important 
general cause of uncertainty is to be found in the 
fact that mechanical and chemical changes of com- 
position in minerals are the rule rather than the 
exception; and, in instances where constancy of com- 
position throughout long periods of geological time 
is asserted, the burden of proof lies with those’ who 
make the assumption. The attempt to assess exact, 
or even approximate times by means of lead ratios is 
premature and entirely invalid. At the same time, 
the weight of the evidence is such as to render it 
exceedingly probable, so far as radio-active evidence 
goes, that geological time must be reckoned at least 
in hundreds of millions of years. There is a high 
degree of improbability that the errors in the radio- 
active methods should always be errors of over- 
estimation. The next step in the investigation of the 
time problem is to be found in a reversion to other 
lines of reasoning. The sea-salt methods, and those 
based on the thickness of the sedimentary rocks in 
particular, need careful reconsideration. Reference is 
made to a number of papers which show that the 
first of these is worthless, and the second based on 
a misapprehension of the nature of deposition. The 
argument from tidal retardation is still of value, as 
also is that from the evolution of carbonate of lime. 
To the author radio-active experiments come as a con- 
firmation of views held on other grounds, but are not 
sufficiently important in themselves to be authorita- 
tive against the balance of the evidence derived from 
other lines of investigation. 
Mathematical Society, March  11.—Sir Joseph 
Larmor, president, in the chair.—Prof. E. W. 
Hobson: Some theorems in the theory of series of 
orthogonal functions.—Major P. A. MacMahon: In- 
NO. 2368, VOL. 95] 

Memoir No. 38. 
vestigations in the theory of the partition of numbers 
by a new method of partial fractions—Col. R. L. 
hippisley : Reciprocal and. parallelogram linkages.— 
Dr. J. R. Wilton: \ pseudo-sphere the equation of 
which is expressible in terms of elliptic functions.— 
T. C. Lewis: Circles and spheres, etc., associated with 
a triangle, orthocentric tetrahedron, etc. 
Paris. 
Academy of Sciences, March 8.—M. Ed. Perrier in the 
chair.—The President announced the death of Prof. 
Hittorf, foreign associate—A. Leduc; Diffraction 
phenomena and the motion of the earth. Pointing out 
an error in the calculations of Mascart in his memoir 
on the modifications undergone by light by reason of 
the movement of the source or the observer.—Emile 
Saillard: Catalysis in the oxidation of the alkaline 
sulphites. The oxidation of alkaline sulphites is re- 
tarded by the presence of saccharose, invert sugar, 
and other bodies, and accelerated by rise of tempera- 
ture. The practical bearing of these observations on 
the process of sugar refining is discussed.—Maurice 
Lugeon and Gerhard Henny: The Canayese zone and 
the southern limit of the Alps.—Med. Gard: A hybrid 
of Fucus ceranoides and F. vesiculosus.—M. Weinberg : 
Researches on gas gangrene. In the majority of cases 
the organism producing the disease is B. perfringens. 
A description of the preparation of a vaccine and an 
antiserum (through the horse) is given; the latter 
appears to offer the most promising results.—Agasse 
Lafont, M. Desmoulins, and F. Heim: Pneumokoniosis 
in metal polishers, 

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