May 13, 1915] 

NATURE 
oe) 


Coal Mines Act, 1911), one in engineering, one in 
metallurgy, one for architects and builders, one for 
teachers (dealing with geology, physics, and chem- 
istry), one on the electrification of collieries, and one 
on gas detection and analysis and by-product recovery. 
Further particulars can be obtained from the chief 
education official, County Hall, Cardiff. 
Tue number of foreign students in German univer- 
sities, according to the Niewwe Courant, was 1435 
during the last winter semester, as against 4715 in 
the previous summer. The decline is primarily due 
to the removal of about 2600 students belonging to 
hostile countries. The students from Austria-Hungary 
numbered 547, as against 814 last summer; the corre- 
sponding decline was :—For Switzerland from 312 to 
146; for Rumania 146 to 111; for Bulgaria 131 to 
105; for Holland there was an increase from 37 to 44. 
During the war foreign students have shown a strong 
preference for Berlin; the chief decline in their num- 
bers being at Kd6nigsberg, Gottingen, Marburg, 
Munich, Strassburg, Freiburg, and Heidelberg. 
SEVERAL gifts in aid of higher education are 
announced in the issue of Science for April 23. Har- 
vard University receives 20,0001. by the will of the late 
Mr. James J. Myers, of Cambridge, Mass., and further 
bequests amounting to 14,600l., to be devoted to cancer 
research at the Harvard Medical School, are 
announced. By the will of Mrs. L. L. Ogden Whal- 
ing, of Cincinnati, Miami University receives 54,o00l. 
The residue of the estate is to be divided between 
Miami University and the Cincinnati Museum Asso- 
ciation, and it is said that each institution may receive 
40,000. The Addison Brown collection of plants 
offered to Amherst College by Mrs. Brown in memory 
of her husband has now come into possession of the 
college. Containing many thousands of specimens 
collected in the United States, Mexico, Porto Rico, 
the Hawaiian Islands, and elsewhere, it is the largest 
accession ever received by the department. 
Tue Imperial Department of Agriculture for the 
West Indies has issued revised courses of reading and 
examinations in practical agriculture. Reading courses 
have for some years been established under the direc- 
tion of the department for the purpose of enabling 
overseers on estates, and others engaged in agricul- 
ture, to acquire by reading knowledge they can apply 
in their everyday work. Examinations are held periodic- 
ally at various centres in the West Indies for persons 
who have previous been registered as students in 
reading courses. Registration in reading courses 
entitles students to certain publications of the depart- 
ment which are recommended for reading. The certi- 
ficates awarded by the department at the examina- 
tions are intended to be a guarantee of a sound general 
knowledge of the fundamental principles underlying 
the practice of agriculture, and also a practical know- 
ledge of at least two crops and their products, such 
as sugar, cacao, cotton, limes, rice, coco-nuts, and 
bananas. 

SOCIETIES AND ACADEMIES. 
LONDON. 
Royal Society, May 6.—Sir Alfred Kempe, vice- 
president and treasurer, in the chair.—G. W. Walker : 
Some problems illustrating the forms of nebulz. The 
paper is concerned with the form of the surfaces of 
equal density when a, quantity of gaseous material 
at uniform temperature, and following Boyle’s law 
as regards pressure and density, is at rest under its 
own gravitation. The differential equation for these 
surfaces is not linear. In the two-dimensional case 
Pockels obtained the solution in terms of two arbitrary 
NO. 2376, VOL. 95| 



functions of complex variables. In the paper the 
solution is put in a form which must give real positive 
density anywhere. Three cases only are considered which 
illustrate respectively aring nebula, a pear-shaped nebula, 
and a nebula with two equal nuclei. Some conse- 
quences of motion of the material are considered. 
Hon. R. J. Strutt: Observations on the resonance 
radiation of sodium vapour. (1) The centres emitting 
resonance radiation of sodium vapour excited by the D 
lines are not persistent enough to be carried along when 
the vapour is distilled away from the place of excita- 
tion. This result is extraordinary, because it con- 
trasts absolutely with the behaviour of sodium vapour 
excited electrically. It also contrasts absolutely with 
the behaviour of mercury vapour, whether excited 
optically (2536 resonance radiation) or electrically. 
(2) The resonance radiation of sodium cannot be seen 
through even a very dilute layer of sodium vapour 
placed in front of it—a layer quite transparent to 
white light. This explains why the spot of superficial 
resonance produced on the wall of a glass bulb can 
only be seen from in front, when the light passes 
to the eye without traversing sodium vapour. From 
the back it cannot be seen, as Dunoyer has observed. 
(3) The resonance radiation of sodium vapour is 
changed in intensity when the vapour is placed in a 
magnetic field. If the exciting flame is weakly salted, 

the radiation diminishes with increasing field 
strength. If the exciting flame is strongly salted, 
the radiation increases to a maximum and then 
diminishes again. (4) A change in intensity of reson- 
ance radiation can also be observed when the exciting 
flame is placed in the magnetic field. In this case a 
weak flame gives diminished radiation in the field, 
while a strong flame gives increased radiation in the 
field. (5) All the facts summarised under (3) and (4) 
can be explained qualitatively and quantitatively, so 
far as the available data will go, by taking into 
account the known Zeeman resolution of the D lines, 
and the observed width and structure of these lines 
as emitted by the flames used. The latter data were 
obtained by observation with a concave grating of 
high resolution.—Hertha Ayrton: Local differences 
of pressure near an obstacle in oscillating water. 
When the water is approaching the mean level there 
is a diminution of pressure, or partial vacuum, 
created in the lee of the obstacle. When the water 
is departing from the mean level the diminution of 
pressure continues high up on the lee side, but over 
the lower part there is a pressure in the opposite 
direction to that of the main stream. The jet in the 
first part of a swing is due to the local current created’ 
by the local difference of pressure; the vortex in the 
second part of the swing is due to the conjunction of 
the main stream with the opposing local current set 
up by the local pressure difference. 
Geological Society, April 14.—Dr. A. Smith Wood- 
ward, president, in the chair.—S. H. Warren: Further 
observations upon the Late Glacial, or Ponder’s End, 
stage of the Lea Valley. With notes on the Mollusca 
by A. S. Kennard and B. B. Woodward. The paper is 
supplementary to one previously published, and de- 
scribes additional sections which increase the range of 
the deposits. They have now been traced for a dis- 
tance of 6} miles along the valley and 25 miles across 
it. The section at Hedge Lane, Lower Edmonton, 
shows several thick, and for the most part undis- 
turbed, Arctic plant-beds, which occur in a deep Drift- 
filled channel. The relative levels and stratigraphy” 
point to the conclusion that the Hedge Lane deposits 
belong to a slightly earlier stage of the Low-Terrace 
River-drift than the deposits of Ponder’s End. Broadly 
speaking, they undoubtedly belong to the same group. 
It is suggested that it would be a convenience if the 
