460 
yearly refraction in Astronomische Nachrichten, 
No. 4699, due to the observations of Venus being 
compared with an ephemeris computed from Leverrier’s 
tables, which, as he says, are in error in a respect 
important in a discussion of this kind. The result of 
the correction is greatly to increase the refraction in 
the neighbourhood of the sun found by Courvoisier. 
RESEARCHES AT THE ALLEGHENY OBSERVATORY.— 
No. 4, vol. iii., of the Publications of the Allegheny 
Observatory contains an account of the orbit of 
A Tauri by Prof. Frank Schlesinger. The variable 
nature of this star was originally discovered by 
Baxandell in 1848, and it was the second star, Algol 
being the first, that was recognised as an eclipsing 
variable. In this research eighty-nine spectrograms 
of the star were utilised, and from these the definite 
elements are given in the paper with the velocity curve 
corresponding to them. Certain residuals indicate 
the presence of some disturbing element in the system 
the nature of which is unknown. Mr. Frank C. 
Jordan, in No. 5 of the Publications, deals with the 
spectrographic observations of ¢ Persei, a variable 
which has received considerable attention by a great 
number of observers. The special character of the 
spectrum and velocity curve, coupled with the changes 
which take place in the spectrum of this star at 
different parts of its orbit, and in its velocity curve in 
different cycles, presents a problem yet unsolved. Mr. 
Jordan’s investigation adds another research to the 
star’s credit, but he finds that no single orbit or 
combination of orbits will satisfy the conditions re- 
quired. In No. 6 of the Publications Mr. A. H. 
Pfund describes a very satisfactory result to his pre- 
liminary thermo-electric measures of stellar radiation. 
While the conditions under which he had to employ 
his apparatus were by no means very favourable to 
secure the best results, yet the magnitudes of the 
deflections he obtained were very’ promising. In his 
paper he describes the general arrangement of the 
apparatus and the thermal junctions used, and gives 
the deflections due to Vega, Jupiter, and Altair. Mr. 
Jordan suggests the desirability of developing thermo 
junctions of still higher sensitiveness, and galvano- 
meters of greater. sensitiveness, and uses them in 
conjunction with the largest reflectors, so that stars 
down to even the 4th magnitude may be studied. 
ZopiacaL MatTrER AND THE SOLAR ConstantT.—In 
citing four cases where zones of asteroids have been 
hypothecated to explain planetary and cometary per- 
turbations and lunar inequalities, Mr. E. Belot, in 
a note in Comptes rendus (No. 18) points out that he 
published in rg05 a formula to take the place of 
Bode’s law, and that certain of the five zones of 
asteroids this formula predicts supply just the material 
in just the right positions. He proceeds further, and 
makes the suggestion that the transit of these zones 
across the sun’s disc may be found to supply the 
probable cause of variation of the solar constant 
established by the work of Abbot, Fowle, and Aldrich. 
THE PHYSICAL SOCIETY’S EXHIBITION. 
HE ninth annual exhibition of the Physical Society 
of London was held in the Physical Department 
of the Imperial College of Science on Tuesday, De- 
cember 16, and attracted the usual large attendance 
at both afternoon and evening sessions. In addition 
to the short discourses which have for some years 
formed a popular feature of the exhibition, a new 
departure was made by the introduction of several 
interesting experiments illustrative of recent research. 
In the exhibition proper about thirty firms showed 
their most recent forms of apparatus. 
The first discourse was given by Mr. Louis Bren- 
nan, C.B., who exhibited and described a simple 
NO. 2303, VOL. 92] 
NATURE 
[DEcEMBER 18, 1913 
apparatus for making large soap films, and demon- 
strated their properties. The film was formed on a 
frame of elastic which was capable of considerable 
extension, thus reducing the thickness of the film 
and showing the consequent change of the colour of 
the reflected light. The second discourse was by 
Prof. J. A. Fleming on the vibrations of loaded and 
unloaded strings. The string was caused to vibrate 
by means of a motor, to the shaft of which one end 
was excentrically attached. The tension could be 
adjusted by moving the pillar to which the other end 
was fixed. The effect of loading was shown by using 
strings twisted together, and also by the addition of 
beads. The reflection which takes place when the 
wave-length is reduced to the distance between suc- 
cessive beads was clearly shown, as was also the 
difference between the effect of a single large load and 
that produced by a load distributed over some dis- 
tance, gradually increasing in amount and then 
diminishing. Prof. Fleming pointed out the applica- 
tion of these experiments to the case of the reflection 
and transmission of light at the boundary of two 
media, and to the more important case of loaded 
telephone cables. 
Among the experiments already mentioned, Mr. 
W. E. Curtis exhibited the band spectrum of helium. 
A vacuum tube at a pressure of several millimetres 
was excited by an induction coil, a condenser and 
spark-gap being included in the secondary circuit. 
With suitable capacity and length of gap, the spec- 
trum shows a number of bands in addition to the 
ordinary helium lines. An experiment illustrating 
ionisation by collision was shown by Mr. F. J. Har- 
low. An electrodeless discharge was excited in a 
spherical bulb and the pressure reduced. 
found that the discharge could be continued at a 
much less pressure than usual if heated lime or 
aluminium phosphate was present to produce ionisa- 
tion. The phosphorescence of mercury-vapour in a 
vacuum excited by light from a mercury lamp was 
exhibited by Mr. F. S. Phillips. Prof. J. T. Morris 
and Mr. J. F. Forrest showed an electric are which 
they suggest for use as a standard of light, the light 
from the positive crater being quite unobstructed. 
Messrs. C. C. Paterson and B. P. Dudding had a 
simple device on exhibition for reducing the glare 
from motor headlights by confining the light to the 
“region below the horizontal on the right-hand side 
as seen from the car. An indicator for use with high- 
speed internal-combustion engines was shown by Dr. 
W. Watson, and also an arrangement for studying 
the spectrum of a burning mixture at different stages 
of the combustion. An experiment on the interfer- 
ence of X-rays by a crystal of rock-salt through which 
they were passed was shown by Dr. G. W. C. Kaye 
and Mr, E. A. Owen, the crystal patterns being visible 
on a fluorescent screen. 
THERE was a large number of interesting features 
among the exhibits of the firms. The Cambridge 
Scientific Instrument Co. had on view an electro- 
static oscillograph designed by Prof. H. Ho and S. 
Koté, of Japan, which possesses important advantages 
over the electromagnetic oscillograph for high-voltage 
work. A contact-breaker for physiological 
which could successively interrupt two circuits with an 
intervening period of from 00002 second to 0-04 
second was also shown. An inexpensive form of 
independent plug contact for resistance boxes was 
shown by Messrs. Gambrell Bros. A simple appa- 
ratus for measuring the pressure of light, designed by 
Mr. G. D. West, was exhibited by Messrs. J. J. 
Griffin and Sons. Mr. R. W. Paul exhibited a large 
number of electrical laboratory instruments, including 
a simple device for projecting an image of the scale 
and pointer of an instrument on a screen for lecture 
It was” 
work + 
