468 
Carboniferous rocks of Kent is given. The Mesozoic 
cover of the coalfield is ignored. The proved area is 
200 square miles. The general strike is about 30° 
south of east and north of west, and the dip of the 
Transition Coal Measures is 2° to 3°. The area is a 
syncline, limited on the north and south by Armorican 
folds, of which the northern has been located. It is 
maintained that the Kent Coalfield is not continuous 
with that of the Pas de Calais. There are reasons for 
believing that the western boundary is a great fault. 
The chief surface-feature of the Coal Measures is that 
of an inclined plane, sloping westwards and south- 
westwards from an elevated region near Ripple and 
Deal. The Lower Carboniferous rocks exceed 450 ft. 
in thickness, and were denuded before the Coal 
Measures were deposited. The Coal Measures consist 
of the Transition Series (1700 to 2000 ft. thick), and 
the Middle Coal Measures (2000 ft.). No Lower Coal 
Measures or Millstone Grit occur. The coals are well 
distributed, and are often of considerable thickness. 
Steam and household coals predominate. The most 
productive portions of the measures are the higher 
part of the Transition and the lower part of the 
Middle Coal Measures.—Dr. E. A. Newell Arber: The 
fossil floras of the Kent Coalfield. The floras of ten 
further borings in Kent are recorded, and the number 
of species known from the Kent Coalfield is raised to 
ninety-six, as compared with twenty-six in 1909. As 
regards the horizons present in Kent, the plant- 
remains indicate that, in the area so far proved, only 
Middle or Transition Coal Measures, or both, occur. 
Linnean Society, December 4.—Prof. E. B. Poulton, 
F.R.S., president, in the chair.—Jane Longstaffi: A 
collection of non-marine Mollusca from the southern 
Sudan. With descriptions of three new species by 
H. B. Preston; and notes on Veronicella nilotica, 
Cockerell, by G. C, Robson, This records the 
Mollusca taken during two visits to the Sudan in 
February, 1909 and 1912. About fifty-three species 
were taken, thirty-four Gasteropoda and nineteen 
Lamellibranchiata, the aquatic, of course, having a 
wider range than the terrestrial forms. _The only 
terrestrial gasteropod found alive was a Veronicella 
nilotica, Cockerell, the second recorded example.— 
A. S. Horne: A contribution to the study of the evolu- 
tion of the flower, with special reference to the 
Hamamelidaceze, Caprifoliacee, and Cornacee. 
Mathematical Society, December 11.—Prof. A. E. H. 
Love, F.R.S., president, in the chair.—Prof. E. W. 
Hobson: The linear integral equation—H. E. J. 
Curzon : Generalised Hermite functions and their con- 
nection with the Bessel functions.—J. Proudman : 
Limiting forms of long-period tides.—Lieut.-Col. 
Cunningham: The number of primes of the same 
residuacity.—R. H, Fowler: Some results on the form 
near infinity of real continuous solutions of a certain 
type of second order differential equation.—s. 
Brodetsky : The potential of a uniform convex solid 
possessing a plane of symmetry with application to the 
direct integration of the potential of a uniform ellip- 
soid.—G. R. Goldbrough ; The dynamical theory of the 
tides in a polar basin.—Prof. J. C. Fields: Proof of 
the complementary theorem. 
CAMBRIDGE. 
Philoscphical Society, November 24.—Prof. Newall in 
the chair.—Prof. A. S, Eddington: The distribution of 
the stars in relation to spectral type. It is well known 
that the concentration of stars to the galactic plane 
is not shown equally by the different spectral classes. 
Type B is the most condensed, and the others follow 
in the order A, F, G, K, M, i.e. the sequence coin- 
cides with the’ usually accepted order of evolution. 
Formerly it seemed probable that this result was due 
NO. 2303, VOL. 92] 
NATURE 
[DrcEMBER 18, 1913 
to a progression in. the average distance of these 
classes of stars, for, on the hypothesis that the stellar 
system is of oblate form, the greater the distance the 
greater will be the concentration to be expected. 
Recent determinations by Boss and Campbell of the 
average distances of the stars of different spectral 
types negative this explanation in a most decided 
manner. It appears, for instance, that the M stars 
are on the average more remote and more luminous 
than type A. There is an outstanding question of 
great difficulty. In parallax investigations it is found 
that the M stars are the faintest of all the types; in 
statistical discussions of proper motions, &c., they are 
found to be the brightest except type B. Similar diffi- 
culties occur with the other types. Russell has put — 
forward the theory that tvpe M consists of two divi- 
sions, “ne being the very earliest and the other the 
latest stage in evolution. Against this it may be 
urged that both divisions of type M are characterised 
by very high velocities in space; this seems to indicate 
a close relation between them.—Dr. G. F. C. Searle = 
(1) The comparison of nearly equal electrical resist- 
ances. Four resistance coils, A, B, C, D, are arranged 
to form the four sides of a Wheatstone’s quadrilateral. 
The coils C, D are approximately equal, but, as their 
ratio is eliminated, it is not necessary to know it. A 
balance is obtained by shunting A, B with large 
resistances a,, b,. The coils A and B are then inter- 
changed and a fresh balance is obtained by shunting 
them with a, and b,. (2) An experiment on the har- 
monic motion of a rigid body.—G. T. Bennett: A 
double-four mechanism.—F. E, Baxandall: The pre- 
sence of certain lines of magnesium in stellar spectra. 
In a recent paper on new series of lines in the spark 
spectrum of magnesium, Prof. Fowler gives spark 
lines of magnesium at wave-lengths 4384-86, 4390-80, 
4428-20, 4434-20, which do not fall into series. Weal 
lines in apparently corresponding positions have been 
found in the spectra of a Canis Majoris (type A,) and 
a Cygni (type A,, Pec.), and the suggestion is made 
that the stellar and laboratory lines are identical. It 
is in such stellar spectra as those mentioned that the 
well-known Mg spark line at wave-length 4481-3 
occurs at its maximum intensity. The new lines 
have not been traced in any other types of stellar 
spectra. 
MANCHESTER. 
Literary and Philosophical Society, November 18.—Mr-. 
Francis Nicholson, president, in the chair.—Prof. 
G. Elliot Smith: The controversies concerning the 
interpretation’ and meaning of the remains of the 
dawn-man found near Piltdown. The author ex- 
plained the nature of the controversies concerning 
other bearings of the Piltdown discovery on the history 
of ancient man: (1) the age of the remains; (2) the 
question of the association of the jaw and the skull ; 
(3) the significance of the jaw and teeth and the 
reconstruction of the missing parts; (4) the recon- 
struction of the brain-cast and the nature of the 
brain; and (5) the place which Eoanthropus should 
occupy in the phylogeny of the Hominide. (1) It is 
practically certain that the fragments are of the 
Pleistocene date. (2) There is definite internal evidence 
that the jaw is not really an ape’s; the teeth it bears 
are human, and the skull, although human, is much 
more primitive than any skull assigned to the genus 
Homo. (3) The reconstruction of the jaw and teeth 
has now been practically settled once for all by the 
subsequent discovery of the canine tooth. (4) He 
considered that there was no longer room for doubt 
as to the position the fragments originally occupied 
in the skull; and it is very improbable that the com- 
plete brain-cast could be more than 1roo c.c. in 
capacity. (5) There seems ample justification for 
