January 17, 1907 | 
NATURE 
281 
tons of wax, and 49,600 tons of sulphate of ammonia. The 
coloured geological map and the sections accompanying the 
memoir are excellent, but the illustrations in the text are 
crude and roughly reproduced. 
In the Electrician of January 11 is an interesting article 
by Mr. G. W. Pickard on the measurement of received 
energy at wirtless stations, reprinted from the Electrical 
Review of New York, which should appeal to all who 
are watching the development of wireless telegraphy. 
The method described by the author is both simple and 
useful, and does not require an elaborate arrangement of 
instruments. A telephonic mode of reception is employed, 
and the sound of a single spark at the sending station 
is reproduced in the telephone by the discharge of a local 
condenser through the same _ receiving circuits, the 
charging potential of the condenser being made equal in 
intensity by variation until this is accomplished. The 
periodicity of the condenser discharge is the same as that 
of the received energy. Then knowing the potential and 
capacity of the condenser, the energy can be deduced by a 
simple formula. An objection to the method is the diffi- 
culty in comparing successive sounds, which cannot be 
accomplished with any degree of accuracy. Also a slight 
change of spark-length at the sending station would 
seriously affect results, and therefore make comparisons of 
the sending station’s performance frcm day to day almast 
impossible. The author mentions a method by which this 
may be partly overcome by the insertion of a key in the 
detector circuit, so as to secure the sending of a truly 
single spark. At the same time, the method described will 
be useful as a rough test in practical work, and should 
help towards the solution of a true formula for long- 
distance work. 
We have received from Mr. T. A. Vaughton, Sutton 
Coldfield, a communication entitled ‘‘ ‘ Growing ’ Alumina,” 
which gives particulars of phenomena observed during the 
passage of electric sparks between a globule of mercury, 
acting as anode, contained in a drawn-out capillary tube 
placed vertically a few millimetres above an aluminium 
plate, which serves as kathode. While sparks are passing, 
a circular *‘ crater ’’ composed of nearly pure alumina in 
a light, feathery form grows round the sparking spot, and 
after a short time the quantity of the product formed is 
considerable. In appearance it resembles moss; when 
examined with a lens during its formation, filaments are 
seen to shoot along the surface of the aluminium in definite 
directions. If the sparking be stopped and the deposit re- 
moved, the formation of the moss again occurs without 
the current being necessary, and the process may be re- 
peated several times in succession. In an atmosphere of 
hydrogen no alumina is formed, and in oxygen but little 
growth occurs. The alumina produced acts on a photo- 
graphic plate even through celluloid. A contributor to 
whom we have submitted the communication informs us 
that the phenomena are probably due to the formation of 
aluminium amalgam owing to mercury being sprayed upon 
the plate by the sparks. It is decomposed by atmospheric 
moisture, giving alumina and mercury, which is free to 
repeat the process. Little action occurs in oxygen because 
of the need of a supply of water vapour. The photographic 
action occurs owing to the production of hydrogen peroxide, 
which will attack a photographic plate through celluloid ; 
hydrogen peroxide is generally formed in similar oxidations. 
Tue Memoirs of the Liverpool School of Tropical 
Medicine, twenty-one of which have been published, are 
to be superseded by a periodical which is to be issued by 
NO, 1942, VOL. 75] 
the school under the title of Annals of Tropical Medicine 
and Hygiene. The annals will be edited by Prof. Ross, in 
collaboration with Drs. Stephens, Todd, Thomas 
Breinl, Mr. Newstead, and Sir Rubert Boyce. 
Tue report on the scientific results of the voyage of 
the S.Y. Scotia is to be published in six quarto volumes 
by the Scottish Oceanographical Laboratory. The first 
volume will contain a narrative of the voyage and a 
summary of results, the second will deal with the physical 
results of the expedition, the third with botany, geology, 
and cartography, and vols. iv., v., and vi. with the 
numerous branches of zoology. The work will be fully 
illustrated with maps, plates, and photographs. Each 
volume will consist of several parts, which will be pub- 
lished separately when ready. Vol. ii. will be issued first, 
and will be ready immediately. It will consist of five 
parts, dealing respectively with meteorology, magnetism, 
bathymetry, physics of the ocean, and tides and waves. 
Orders, accompanied by a remittance for vol. ii., 425., 
should be sent to the director, Scottish Oceanographical 
Laboratory, Surgeons’ Hall, Edinburgh. 
and 
OUR ASTRONOMICAL COLUMN. 
THE TEMPERATURE OF THE Moon.—In a paper appear- 
ing in the Astrophysical Journal (No. 5, vol. xxiv.), Mr. 
F. W. Very discusses Mr. Coblentz’s recently-published 
conclusion that, from an investigation dealing with the 
reflection of heat radiations from various mineral sub- 
stances, it may be deduced that the apparent temperature 
of the lunar surface is chiefly due to reflected solar radi- 
ations, and that the actwal temperature may be about 
—225° C., in accordance with Langley’s first conclusion. 
Mr. Very points out that his investigations of the radi- 
ations show that the larger part of them are not merely 
specularly reflected, but are radiated, the moon having first 
absorbed the heat from the solar radiations. Instead of 
—225° C., he suggests that the temperature of the lunar 
body may reach a maximum of about 100° C., the cor- 
rected lunar-radiation curve being similar to that appertain- 
ing to bodies not much below the temperature of boiling 
water. 
Tue Hetium Line, D,, IN THE SOLAR SpEcTRUM.—In a 
communication to the Observatory (No. 379) Mr. Buss, 
of Ashton-on-Mersey, states that he has repeatedly seen 
the helium line, D,, as a dark line, when examining parts 
of the solar disc, within the sun-spot zone, on which there 
were no telescopic signs of unusual activity. He has 
previously recorded the appearance of this line in the 
region of various spots, but never in the spot umbra itself, 
and thinks that it might be found very often if continuous 
observations were made for the purpose. He also suggests 
the possibility of D, being a regular feature of the Fraun- 
hoferic spectrum, the line being too fine to be seen with 
our present instruments, except on occasions when the 
region examined is subject to some slight disturbance. 
A Wuitrt Spot on Jupiter’s Tuirp SateLiite.—In No. 
4147 of the Astronomische Nachrichten, Senor José Comas 
Sola, director of the Fabra Observatory, records the 
observation of a white spot near the north pole of 
Jupiter’s third satellite on November 23, 1906. The 
observation was made with powers of 450 and 750 on an 
equatorial of 38 cm. aperture, and with the latter magnifi- 
cation the spot was seen, with great facility, as being 
intensely white and bordered by a very dark area; Senor 
Sola thinks that much smaller instruments may reveal 
this feature. With a steady image other, dark, spots were 
seen, the whole disc of the satellite appearing as a reduced 
image of Mars. The observation was made between 13h. 
and 14h. 15m., but no displacement of the spot was 
detected. 
A RemarkaB_e Neputa.—On some plates taken during 
September, 1906, Prof. Max Wolf has found an extended 
nebula near to the star 26 Ceti. Practically all extended 
nebulosities are situated in or near to the Milky Way, but 
this is a remarkable exception, for it is removed some 
