OcTOoBER 26, 1899] 
unsuccessful attempts had been made to lay it—and in 
the following year, some months after it had been re- 
covered and completed, both it and the new 1866 cable 
broke, while one of them broke again the following 
year. 
The fact is that to construct an Atlantic cable at all in 
NATURE 
those days was a very courageous thing to do; to lay it | 
successfully, even with many failures, evinced a faith 
and confidence in engineering skill and a dogged spirit | 
of determination that make one proud of the Anglo- 
Saxon race. To every one who took a prominent part 
in the enterprise, as certainly did Sir Charles Bright, all 
honour is due as well as the thanks, not only of his 
contemporaries, but of all who have followed him. 
But we are inclined to think that the authors of this 
memoir would have been well advised had they not 
allowed their reverential memory for the brother of the 
one and the father of the other to lead them to adopt the 
painter’s only method of representing a bright light, 
viz. by intentionally throwing the rest of the picture into 
shade. 
Volume ii. deals with the telegraph to India, Sir 
Charles’ parliamentary life, the West Indian cables, Sir 
Charles’ work in connection with mining, fire alarms, 
telephony, electric lighting, the Paris Electrical Exhi- 
bition of 1881, the Institution of Electrical Engineers, 
Freemasonry, and concludes with various appendices. 
This life-story is distinctly interesting, but its interest 
would have been even greater had the matter been com- 
pressed into about half, or at any rate into not more than 
two-thirds, the space. Before a second edition appears we 
would suggest that such scientific crudities as the fol- 
lowing should be altered :—‘‘ A current which was esti- 
mated by the experts to amount to about 2000 volts.” 
“In the absence of a determinate unit of inductive 
capacity or quantity of electricity condensers were em- 
ployed for the first time.” ‘When electricity passes 
through this surrounding coil of wire, the magnet 
and mirror take up a position of equilibrium between the 
elastic force of the silk and the deflecting force of the 
current. . . . The magnet is artificially brought back to 
zero with great precision after each signal by the use of 
an adjustable controlling magnet.” 
OUR BOOK SHELF. 
The Maintenance of Solar Energy. By F.R.A.S. Pp. 20. 
(London: The Southern Publishing Co., Ltd., 1899.) 
THE author of this short essay is not satisfied with the 
current ideas as to the maintenance of solar energy, but 
believes his new views tend to remove much of the 
difficulty. So far as can be judged by these “pre- 
liminary notes,” however, the theory advanced is one 
which is not likely to convince any one but its author. 
Interplanetary water vapour and the periodical in- 
dulgence of the sun in cometary vapour baths appear to 
play an important part, the idea being that as a result of 
their action the radiant forces of the sun are confined 
within the limits of the solar system. The recurring 
absorption of the planets by the sun and subsequent 
disruption into new systems are other features of a theory 
which has its principal strength in the fact that there are 
no means of testing its chief teachings. The author’s 
name does not appear on the title-page, but the preface 
is signed by J. H. Brown. 
NO. 1565, VOL. 60] 
615 
Official Report of the National Poultry Conference held 
at Keading in July 1899. Edited by the Honorary 
Secretaries, Edward Brown, F.L.S., and F. H. Wright, 
F.S.A.A. Pp. xvi + 138. 
THE conference of which this is a report was the first of 
its kind held in this country, and its success should lead 
to other similar meetings. The report shows that most 
of the papers were of a scientific character, and its pub- 
lication should extend the knowledge of the principles 
which lead to successful poultry-farming. Among the 
subjects dealt with are: the science and practice of farm 
poultry keeping, the parasitic diseases of poultry, and 
the assistance afforded by science in the production of 
eggs and poultry. There will be hope for British 
agriculture when the spirit which pervades these papers 
guides the operations of all who are concerned with rural 
industries. 
The Story of Ice tn the Present and Past. 
Brend. Pp. 228. 
1899.) 
AN instructive addition to the “Library of Useful 
Stories,” containing a clearly-written account of the 
physical properties and geological operations of ice. 
General readers should find the volume interesting. We 
notice that the cavities formed by glacier mills are 
termed “potholes or giant’s kettles” ; but the former 
term ought to be restricted to the circular holes found 
in the beds of streams. 
By W. A. 
(London: George Newnes, Ltd., 
LETTERS TO THE EDITOR. 
[The Editor does not hold himself responstble for opinions ex- 
pressed by his correspondents. Netther can he undertake 
to return, or to correspond with the writers of, rejected 
manuscrebts tntended for this or any other part of NATURE. 
No notice ts taken of anonymous communications. | 
Effect of Vibration on a Level Bubble. 
I HAVE never seen any notice of this phenomenon, but it is 
sufficiently curious to be worth describing. 
I had fitted on a bicycle a small level with a radius of curv- 
ature of a foot, in order to note gradients without dismounting. 
In general this answered very well, and the gradients could be 
satisfactorily measured with an accuracy of about I percent., 
but when going over certain classes of rough road (e.g. granite 
paving), the roughnesses of which had a definite pitch, it was 
noticed that though the road might be level, the bubble would 
at certain speeds indicate gradients as steep as one in eight or 
one in six, and remain steadily in such positions as long as the 
speed and character of the road remained constant. It seemed 
a matter of chance whether the bubble moved so as to indicate 
an up or a down gradient. 
The explanation is to be found in the coincidence of a natural 
period of the bubble, due to the surface tension of the fluid, and 
the interval which elapses between successive encounters of the 
bicycle wheel with the roughnesses of the road. 
Owing to the level being at a certain height above the 
ground (it was attached to the upper tube of the frame), any 
pitching of the bicycle, such as is caused by going over rough 
ground, gives a backward and forward motion to the frame in 
addition to the general onward movement. 
We may suppose, for the sake of simplicity, that this back- 
ward and forward motion is a simple harmonic. 
Whena level is subjected to a harmonic displacement parallel 
to the mean direction of the tube, the bubble will endeavour at 
each instant to place itself at that part of the tube where the 
tangent is at right angles to the resultant of gravity and the im- 
posed acceleration. Thus the bubble tends to move relatively 
to the tube in the direction of the displacement of the latter, 
and would always occupy its true position with regard to the re- 
sultant if its motion under the variable force was quick enough. 
The motion of the bubble, however, is very slow compared with 
that required to bring about this result ; but although the forces 
which act on the bubble have not time to move it far in each 
period, they do deform it, and the deformation may become 
