434 NATURE [DECEMBER I1, 1913. 
working of the furnaces; the gases must escape at 
the lowest temperature which will retain the mercury 
as vapour, and the hot spent ore must be used to heat 
the air-supply of the furnaces. As illustrating the 
difficulty of retaining the metal, it is mentioned that 
at the New Almaden mine in California, 2000 flasks 
(135,000 Ib.) of mercury were taken from the ground 
under one of the furnaces, the metal having pene- 
trated 27 ft. to bedrock. 
The Engineer for December 5 contains an account 
of the motor ship Arum, launched last week from the 
yard of the builders, Messrs. Swan, Hunter and Wig- 
ham Richardsons, Ltd. ‘This vessel is an addition to 
the comparatively small number of motor ships of 
which both hull and engines have been built in this 
country. Her dimensions are 360 ft. length over all, 
by 47 ft. beam, by 27 ft. moulded depth; she is to 
carry about 5600 tons dead weight on a draught of 
21 ft. 6 in. The main engines, built by the same 
firm, consist of a pair of four-cylinder two-cycle rever- 
sible Diesel engines, designed for 1150 brale-horse- 
power at 135 revolutions per minute; the speed will 
be about 105 knots. The vessel has been built to 
the order of Sir Marcus Samuel for the carrying of 
general cargo, and is to trade to the Persian Gulf. 
Oil from the Persian oil wells is to be employed, a 
favourable ten years’ contract having been secured for 
the supply of Sir Marcus Samuel’s fleet. 
An illustrated article in Engineering for December 5 
on the channel steamer Paris gives some up-to-date 
information regarding the development of geared 
turbines. Absence of wear, freedom from noise, 
durability, and low frictional loss have been achieved. 
The loss due to transmission and reduction with 
double helical wheels is under 2 per cent., whereas 
in the hydraulic and electrical systems it is quite five 
timesas great. It has been contended that the windage 
loss in the running idle of the astern turbines partly 
nullifies this advantage; as the astern turbines revolve 
in the vacuum of the condenser, the losses for them 
amount to only o-5 per cent. Accounting also for the 
loss due to the thrust-block associated with geared 
turbines, the mechanical gearing gives an efficiency of 
about 97 per cent. as compared with about 90 per 
cent, in other systems. In the Paris, the power 
transmitted through two gear-wheels is 14,000 shaft- 
horse-power. It is but four years since the first use 
of such gearing, and to-day there are 435,450 horse- 
power completed or under construction. 
THE 1913 issue of ‘“‘The Year-Book of the Scien- 
tific and Learned Societies of Great Britain and Ire- 
land”’ has been published by Messrs. Charles Griffin 
and Co., Ltd., at the price of 7s. 6d. It will be 
remembered this useful annual publication is compiled 
from official sources, and it is appropriately described 
on the title-page as a record of the work done in 
science, literature, and art during the session 1912-13 
by numerous societies and Government institutions. 
We notice*in the case of the British Association that 
though particulars are given of the meeting held at 
Dundee in September, 1912, no information about the 
Birmingham meeting of September last is included. 
NO. 2302, VOL. 92] 
OUR ASTRONOMICAL COLUMN. 
THE STRUCTURE OF THE UNIVERSE.—The November 
issue of Scientia contains an article by Prof. J. C. 
Kapteyn, entitled ‘‘On the Structure of the Universe,” 
which should be read by all those who wish to obtain 
the most modern view of this most fascinating 
problem. It was Prof. Kapteyn who, in 1904, first 
determined the elements of the two star streams, and — 
since then a great advance has been made in extend- 
ing our knowledge in this direction. In the present — 
article, and, it may be added, it is written in a very 
clear and concise manner, he places before the reader 
the general nature otf the problem, and step by step 
he points out how the various researches of many _ 
observers are coordinated and brought to bear in 
concentrated form on the question of the structure of — 
the universe. The subject being so vast, he confines 
himself here mainly to that portion concerned with 
star-streaming, and considers the questions, What has 
the discovery of star-streaming done, and, What does 
it promise to do for the solution of the problems (1) 
that of the distance, and (2) that of the history or 
evolution of the stellar system, Prof. Kapteyn utilises 
a modified form of Secchi’s stellar classification, and 
states that there is much evidence to show that this 
classification is a natural one, and that the order of 
evolution is as follows :—The helium stars being those 
of recent birth, while we come to older and older stars 
in passing from the helium stars to the stars of the 
first, then to those of the second, and finally to those 
of the third type. 
In speaking of the spectra of such groups of stars — 
as the Hyades, Pleiades, Ursa Major group, &c., he 
says:—'‘The groups that do not now contain any 
helium stars must have contained them formerly in 
great numbers. Going back in time still further, these 
helium stars must have been generated from some other 
matter, probably nebulous matter. Therefore in a 
remote past the groups of the Hyades and Ursa Major 
must have been full of nebula. So far as I know there 
is no trace of nebulosity now. So there must have 
been an epoch in the past that nebulous matter was 
exhausted, had probably all gone to the formation of 
stars.” 
JourNAL OF THE RoyaL AsTRONOMICAL SOCIETY OF 
Canapa.—In the September to October number of the 
Journal of the R.A.S. of Canada, Mr. H. B. Collier 
writes on meteorites, and after giving a brief sum- 
mary of early falls, he refers in greater detail to the 
“Cape York’’ meteorites brought by Peary from 
Greenland, and to the ‘‘ Williamette ’’ meteorite found — 
nineteen miles south of Portland, Oregon. A very 
excellent translation from Ciel et Terre of a most 
interesting article by G. van Biesbroeck on the astro- ~ 
nomical works of Olaus Roemer, the discoverer of — 
the velocity of the transmission of light, is printed. 
The fire at Copenhagen in 1728, destroyed most of 
Roemer’s manuscripts, but a portfolio bearing the 
inscription ‘‘ Adversaria,”” survived, and has recently 
been published by the Danish Society of Sciences. 
Valuable historical facts were contained in it, and 
are here described. The subject of the boundary sur- 
vey between Canada and the United States east of © 
the St. Lawrence is dealt with by Mr. T. Faweett, 
and he describes the part Airy took in the arrange- 
ments for the carrying out of the necessary astro- 
nomical work which such a survey demanded. A 
description is also given of the methods employed on — 
that occasion (1842) by the British and American 
parties. 
New NEBULA: AND’ VARIABLE Stars.—In No. 4697 
of the Astronomische Nachrichten, Mr. C. R. 
! D’Esterre describes an object the abnormal behaviour 
