APRIL 21, 1904] 
NATURE 589 
were chiefly of a biological and geological character; in 
Section C various engineering questions were discussed, and 
in Section D great prominence was given to education, 
philosophy and sociology. The volume deals with forty- 
seven papers, which are with a few exceptions printed in 
full or abstracted. 
Up to the present the alloys of nickel and iron have 
attracted attention chiefly on account of the fact that alloys 
containing about 35 per cent. of nickel have an exceedingly 
small coefficient of expansion, which in certain cases may 
even become negative. Their elastic properties appear, 
however, to be of equal interest and importance, and a 
paper on this subject, by M. Guillaume, in the Séance of 
the French Physical Society, contains a number of im- 
* portant data. At ordinary temperatures the modulus of 
elasticity reaches a maximum at 29 per cent. and a mini- 
mum at 45 per cent. of nickel, and between these limits the 
modulus of elasticity increases with the temperature, whilst 
two alloys must exist in which the modulus is independent 
of the temperature. These results can be explained by sup- 
posing that the change from B to y iron is accompanied 
by a large increase in*the modulus of elasticity, and that 
in the alloys referred to this transition is brought down 
to the %ordinary temperatures and extended over several 
degrees. 
IN recent months some attention has been paid to the 
problem of bringing about electrolytic decomposition by 
means of alternating currents. The most important paper 
that has appeared on the subject is that by Le Blanc and 
Schick in the Zeitschrift fiir physikalische Chemie, in which 
experiments are described on the dissolution of metals in 
various solvents by the aid of alternating currents of fre- 
quency ranging from 72 to 38,600 alternations per minute. 
In the simpler cases, such as the dissolution of copper in 
sodium hydrogen sulphate, the weight of metal dissolved 
is very small, and even at a frequency of only 72 is less 
than one-third of that calculated from Faraday’s law. On 
the other hand, potassium cyanide, especially in concen- 
trated solutions and with a high current density, dissolves 
the metal freely even with very high frequencies, and in 
one experiment the weight of copper dissolved amounted 
to no less than 66 per cent. of the theoretical quantity when 
the frequency was above 30,000; this result is probably due 
to the formation of complex double cyanides in which the 
metal forms part of the acid radicle, and so is hindered 
from being re-deposited on the electrode. 
Tue additions to the Zoological Society’s Gardens during 
the past week include a Campbell’s Monkey (Cercopithecus 
campbelli) from West Africa, presented by Mr. J. A. L. 
Campbell; a Vulpine Phalanger (Trichosurus vulpecula) 
from Australia, presented by Mr. Herbert A. Parkes; an 
African Civet Cat (Viverra civetta) from Africa, presented 
by Lieut. H. Nelson, R.A.; three Reeve’s Pheasants 
(Phasianus reevesi) from northern China, presented by Miss 
J. Mann; a Blue-fronted Amazon (Chrysotis oestiva) from 
South America, a Princess of Wales’s Parrakeet (Polytelis 
alexandrae) from Australia, presented by Mrs. St. Clair 
Christophers; a Bonnet Monkey (Macacus sinicus) from 
India, a Blackish Macaque (Macacus fusco-ater) from the 
Celebes, a Striped Hyzena (Hyaena striata) from North 
Africa, a Virginian Opossum (Didelphys virginianus) from 
North America, a Burrowing Owl (Speotyto cunicularia) 
from South America, a Grey Parrot (Psittacus erithacus) 
from West Africa, five Eyed Lizards (Lacerta ocellata), 
south European, deposited; a Mouflon (Ovis musimon), 
born in the Gardens. 
NO. 1799, VOL. 69 | 
OUR ASTRONOMICAL COLUMN. 
Return or Brooxs’s Comet.—A telegram received from 
the Kiel Centralstelle on April 17 announces that Brooks’s 
comet was observed at Geneva at 9h. 50m. (Geneva M.T.) 
on April 16. Its position at that time was -R.A.= 
16h. 58m. 8s., decl.=+44° 10’, and it was slowly travelling 
northward. Both a nucleus and a tail were seen. 
A second telegram received on April 18 announces that 
Prof. Kobold observed the comet on April 17, and found 
its position, at 11h. 34m. os. (Kiel M.T.),. to be REAL 
16h. 56m. 23-8s., decl.=+44° 43’ 47”. 
The above data show that on April 16 the comet was 
nearly on a straight line joining o and « Herculis, and 
rather nearer to the former than the latter, also that the 
comet is apparently travelling towards Draco. 
ABSORPTION OF STAR-LIGHT BY A ComeEr’s TaiLt.—In No. 
3914 of the Astronomische Nachrichten Dr. Max Wolf dis- 
cussed a photograph which led him to the conclusion that 
the light of the star B.D.+63°-1056 was affected by selective 
absorption in passing through the tail of comet 1903 IV. 
on July 25, 1903. 
The consideration of later 
however, to doubt the reality 
which he now considers may have been due to a photo- 
graphic effect produced by the comet’s light on the film of 
the negative (Astronomische Nachrichten, No. 3934)- 
Tue Spectra or Nov#.—In an article published in No. 
3917 of the Astronomische Nachrichten, Herr H. Ebert ex- 
plains how the multiple character of the lines in the spectra 
of new stars may readily be accounted for by supposing it 
to be due to ‘‘ anomalous refraction’’ in the layers of 
vapours, of different characters and densities, through which 
the light has to pass between the source and the observer. 
By a number of curves and diagrams he shows that in the 
complex strata, which may be reasonably supposed to exist 
in the vapours surrounding a new star, the light would be 
refracted hither and thither until, when it emerged from 
the outer layers, the distribution of the brightness in the 
spectrum would have been considerably modified by 
anomalous refraction. 
The “‘ shifting ’’ of spectral lines in the experiments which 
have been performed by several observers on the spectrum 
of the spark discharge under various liquids may, accord- 
ing to Herr Ebert, be readily explained by this theory. 
Nesutosity ArounD Nova. Perse!.—In No. 2, vol. xix., of 
the Astrophysical Journal, Mr. Otto Luyties, of Baltimore, 
discusses the theories which have been promulgated in refer- 
ence to the nature and the expansion of nebulosity around 
Nova Persei, and points out the effect which the shape of 
the body concerned might have upon the observed velocities. 
He states that the previous estimations of the parallax of 
the Nova nebula and of the rate of its expansion have been 
partly based on the probably erroneous assumption that the 
emanations which caused the illumination were originally 
propagated in a direction at right angles to the line of sight. 
If, however, the mass illuminated were spherical in form, 
the resulting distortion on the photographic plate would 
lead to serious misconceptions as to the rate of expansion 
and the nature of the emanation. Mr. Luyties then dis- 
cusses the possible effects of such distortion, both for the 
case of radial illumination from the centre and for that in 
which the emanation proceeded from a point on the boundary 
of the sphere, and shows that the correction for such dis- 
tortion, when a likely value is allotted to the parallax, could 
be made to account readily for the apparent retardation of 
the illuminations, and for other anomalies which have been 
observed, when the actual velocity of the emanations was 
of the order of that of light. 
STELLAR DisTRIBUTION.—A communication from Mr. J. E. 
Gore to No. 343 of the Observatory gives the results 
obtained from a count of the stars of each magnitude from 
the third to the sixteenth on a chart of the Pleiades pub- 
lished in Klein’s Star Atlas. This chart covers three square 
degrees, and Mr. Gore finds that the actual value of the 
ratio for all magnitudes is considerably less than 4, which 
is the theoretical value if all the stars were equally dis- 
tributed in space. 
The total number of stars counted on the chart was 1281, 
and this would give for the whole sky, if of uniform rich- 
ness, a total of 17,615,031. 
observations has led him, 
of the apparent absorption, 
