JANUARY 10, 1907] 
NATURE 257 
inch, square inch, and cubic inch as standards of length, 
area, and volume, and the weight of a cubic inch of water 
at a certain temperature as the standard of weight. 
Tue issue for 1907 of the ‘* Science Year-book, with 
Astronomical, Physical and Chemical Tables, Summary of 
Progress in Science, Bibliographies and Diary,” edited by 
Major B. F. S. Baden-Powell, and published by Messrs. 
King, Sell and Olding, Ltd., differs little from that of 
last year. A general article of fewer than ten pages on 
the progress of science in 1906 has superseded the com- 
paratively full summaries in various scientific subjects 
given in former years. We observe that the ‘* Year-book ”’ 
can be obtained in an abridged form without the diary. 
Tue twenty-third annual issue of the “‘ Year-book of the 
Scientific and Learned Societies of Great Britain and 
Ireland,’? which has been published by Messrs. Charles 
Griffin and Co., Ltd., provides a convenient short record 
of the work done by numerous societies and Government 
institutions in science, literature, and art during the session 
1905-6. The information has been compiled from official 
sources, and the majority of societies and associations in- 
cluded in the volume have demonstrated, by published 
papers, their activity in extending and disseminating know- 
ledge. The editor may be congratulated upon the produc- 
tion of a work of reference which is of distinct service. 
A PRICE-LIst of invar and its applications, issued by Mr. 
J. H. Agar Baugh, 92 Hatton Garden, E.C., contains 
some interesting notes on the specific properties of this 
valuable alloy of nickel-steel. Invar is sold in three 
grades, and the guaranteed maximum of the coefficient of 
expansion of the middle quality is only 0-ooo00r5 per 1° C., 
while that of the highest grade is much less. For 
pendulum rods, compensation balances for marine chrono- 
meters and pocket watches, standard measures of length, 
tapes for measuring base-lines, and many other purposes, 
invar has proved particularly valuable, and its use in 
scientific instruments is likely to be greatly extended. 
Tue first number of a new weekly journal known as 
Electrical Engineering was published on January 3. The 
periodical will deal with the subject of electrical engineer- 
ing, particularly from the practical and utilitarian aspect, 
and is intended for the engineer rather than the electrician. 
The number of well-reproduced drawings to scale and of 
special photographs showing details of constructional work 
is large, and the paper is, as a whole, particularly attrac- 
tive. Among other articles may be noticed one on the 
new Great Northern, Piccadilly, and Brompton Railway, 
and an incidental reference in another part of the paper 
gives the information that all the rolling-stock for the 
latest tube is of Continental manufacture. If the standard 
of the first number is maintained, the new periodical 
should have a successful career. 
OUR ASTRONOMICAL COLUMN. 
EPHEMERIS FOR Comet 1906g (THIELE).—A _ further 
ephemeris for comet 1906g, extending to February 16, is 
given in No. 4143 of the Astronomische Nachrichten by 
Herr Georg Dybeck. This ephemeris shows that the comet 
is now (January 10) about 1° north of @ Draconis, and is 
only about one-third as bright as when discovered. 
THE OBSERVATION OF ToTaL SoLar EcLipses.—Observers 
of total eclipses of the sun will find much to interest them 
in the address delivered by M. le Comte A. de la Baume 
Pluvinel to the Astronomical Society of France, and pub- 
lished in the Bulletin for December, 1906. 
The lecturer dealt chiefly with the details of the pre- 
NO. 1941. VOL. 75] 
liminary preparations, which commence at the moment 
that the astronomer decides to observe the eclipse—usually 
some months before the actual day—and are not con- 
cluded until the observations are actually in progress. In 
eclipse reports these preparations: are generally only sum- 
marily dealt with, and the inexperienced reader will be 
surprised, on reading the lecture, to learn of the innumer- 
able minutiae which have to be considered and dealt with 
if success is to attend the observations. The lecturer also 
named the most famous eclipse observers in the several 
countries which have participated in these important 
observations, directing special attention to any exceptional 
methods employed, as, for example, the utilisation of 
men-of-war and their trained personnel by Sir Norman 
Lockyer at several eclipses. 
OpserRvATIONS oF Mars.—In the December (1906) 
number of the Bulletin de la Société astronomique de 
France, M. José Comas Sola, director of the Fabra 
Observatory (Barcelona), gives an illustrated account of his 
observations of Mars during the opposition of 1905. The 
following points, among others, are worthy of notice :— 
On April 26 M. Sola saw a ‘‘lac”’ at the intersection of 
Phison and Orontes, and the Euphrates, although perfectly 
visible, was always diffuse, despite the fact that, at times, 
the seeing was very good. On April 28 changes were 
observed which were evidently due to atmospheric changes 
on the planet. The ‘‘seeing’’ on May 9 was superb, 
and, as shown by the drawing for this date, ‘‘ canaux ”’ 
and ‘‘lacs’’ were seen very distinctly, the latter forming 
the corners of the pentagon around the Elysium. The 
Propontis was seen’ to be rather dark and double, with 
good ‘‘seeing,’”? on May 17, at 1rh. gom. (G.M.T.), but 
at 12h. 40m. it seemed quadruple, formed by four ‘‘ lacs ”’ 
disposed at the corners of a square. 
TRANSIT-CIRCLE OBSERVATIONS.—Parts i. to iii., vol. iv. 
(second series), of the Publications of the U.S. Naval 
Observatory contain a large number of transit-circle 
observations, with their discussions and reductions. 
In part i. the observations made with the 6-inch transit 
circle during the period 1900-3 are dealt with and the 
results tabulated. It is interesting to note that whilst the 
variations of this instrument are much smaller since the 
substitution of brick for stone piers, they are still 
important, and Prof. Littell, from a discussion of the 
constants for 1903, shows that they are dependent upon 
the temperature variations. The azimuth constant shows 
a regular annual variation of —o-o11s. per 1° F., and a 
diurnal variation of about half that amount. In part ii. 
the observations made during 1866-91 are collected and 
discussed in a uniform manner, whilst part iii. is devoted 
to the discussion of the 6-inch transit-circle observations 
of standard and zodiacal stars made during 1901 and 
1902. 
Tue ‘‘ CoMPANION TO THE OpsERVaTORY.’’—Only a few 
changes are to be noted in the current issue of the in- 
dispensable annual the ‘‘ Companion to the Observatory.” 
Owing to the continued increase in the number of known 
variable stars, the list of ephemerides supplied by M. 
Loewy is given in a somewhat different form, and the 
Greenwich mean astronomical time, from noon to noon, 
has been substituted for the civil, midnight to midnight, 
time employed in recent years. The addition of stars 
fainter than magnitude 6-5 has increased the number of 
lunar occultations given. The usual diagram of Saturn’s 
satellites is omitted, because their plane passes through 
the earth during the current year. The ‘‘ Companion ”’ is 
published by Messrs. Taylor and Francis, price rs. 6d. 
““ Tue HEAVENS AT A GLANCE, 1907.’’—For all who take 
an interest in astronomical phenomena, and have but little 
time to spare and but modest instrumental equipment, Mr. 
Mee’s card, ‘‘ The Heavens at a Glance,’’ is the handiest 
and cheapest calendar published. As in previous issues, it 
gives the chief events for each month, the dispositions of 
the sun, moon, and planets throughout the year, notes on 
eclipses, meteor showers, and variable stars, and a pair 
of star maps by which the observer may recognise the 
chief constellations and stars at any season of the year. 
The price is sevenpence, post free, from Mr. A. Mee, 
Llanishen, near Cardiff. 
