522 
NATURE 
[JULY 16, 1914 
of silicon, the impurities being titanium, iron, and 
aluminium. This material has been used in the 
present research. The paper gives a complete list 
of silicon lines from A 2124163 in the ultra-violet to 
A 6371'032 in the extreme red, with some remarks 
referring to missing or doubtful lines.—Prof. S. P. 
Thompson: Note on Mr. Mallock’s observations on 
intermittent vision. In his paper of December, 1913, 
on intermittent vision, Mr. Mallock discussed the 
phenomena observed when a rotating disc of twelve 
black sectors painted on a white ground is viewed 
while a slight mechanical shock is given to the body 
or head. He concluded that a mechanical acceleration 
imparted thus to the nerve structures on which vision 
depends produces a momentary periodic paralysis. 
The author, repeating Mr. Mallock’s experiments, 
finds that effects of precisely the same kind appear 
when, on viewing the rotating sector disc in a mirror 
mounted elastically on a support, slight mechanical 
shocks are given to the mirror instead of to the 
observer. He therefore attributes the effects, both in 
Mr. Mallock’s original experiments and in his own, 
to momentary minute displacements of the image on 
the retina, stimulating rods and cones which are 
relatively unfatigued and which therefore are momen- 
tarily of greater sensitiveness.—T. R. Merton: 
Attempts to produce rare gases by electric discharge. 
An investigation has been made of the apparent pro- 
duction of neon and helium by electric discharges in 
vacuum tubes. An apparatus has been designed in 
which protection from atmospheric contamination can 
be secured by a mercury seal throughout the experi- 
ment. It has been found that the presence of argon 
in the residual gases furnishes an exceedingly sensi- 
tive test for atmospheric contamination, and that a 
mercury seal can only be relied on if precautions are 
taken to ensure that the mercury and glass are 
scrupulously clean. The author has not been success- 
ful in reproducing the conditions necessary for the 
production of neon and helium.—A. C. G. Egerton: 
The analysis of gases after passage of electric dis- 
charges.—C. T. Heycock and F. H. Neville: Dilute 
solutions of aluminium in gold.—Prof. F. G. Donnan 
and G. M. Green: The variation of electrical potential 
across a semipermeable membrane.—J. H. Jeans: The 
potential of ellipsoidal bodies and the figures of 
equilibrium of rotating liquid masses. Sir G. 
Darwin was convinced that the pear-shaped series 
of figures of equilibrium discovered by Poincaré 
was initially stable, while M. Liapounoff had 
with equal conviction announced that it was 
unstable. The present investigation was under- 
taken primarily in the hope of deciding between these 
two views. The main conclusion arrived at is some- 
what disappointing. It is that, in spite of the labours 
of Poincaré, Darwin, and Liapounoff, we have still 
no definite knowledge as to the stability or instability 
of the pear-shaped figure. All these investigators 
have worked at the question of the stability of the 
pear-shaped figure carried so far as the second order 
of small quantities. The present paper indicates that, 
so far as second-order terms, there is a doubly- 
infinite series of such figures which can, of course, 
be broken up into linear series in as many ways as 
we please. So far as can be seen, Sir G. Darwin has 
concerned himself with only one of these series, while 
M. Liapounoff has presumably dealt with a different 
series. It appears that the true linear series demanded 
by the general theory of Poincaré (Act. Math., vii., 
p- 259) only reveals itself when the computations are 
carried so far as the third order of small quantities, 
a conclusion which is confirmed by the result of a 
previous investigation on the figures of equilibrium of 
NO. 2336, WVOL.493)| 
rotating cylinders (Phil. Trans., A. 200 (1902), p. 67).— 
Dr. C, Chree: ‘Lhe 27-day period in magnetic pheno- 
mena. ‘he author has dealt in two previous papers 
in the Philosophical Transactions with data which 
seemed to confirm the reality of a period of about 
27 days in magnetic phenomena, in the sense that 
it any particular day is more than ordinarily dis- 
turbed, or more than ordinarily quiet, the day which 
is 27 days later shows a decided bent in the same 
direction. In these investigations use was made 
almost entirely of magnetic ‘character”’ figures. As 
international “character” figures do not exist for 
| years prior to 1906, and as ‘‘character’’ figures 
assigned at one station are open to certain objections, 
it appeared desirable to ascertain whether or not the 
27-day period is clearly shown in the average year by | 
the amplitude of the daily ranges of the magnetic 
elements. This is investigated in the present paper, 
use being made of the Kew declination horizontal 
force and vertical force ranges from 1890 to 1900, 
treated independently. The period is found to be 
clearly shown by the range of each element.—J. J. 
Nolan: Electrification of water by splashing and 
spraying. Water is broken into fine drops—(1) by 
allowing it to fall into a horizontal air stream of high 
velocity; (2) by spraying. The size of the drops and 
the charge per c.c. of water are measured. The 
conditions of the experiments enabled measurements 
to be made for drops of different sizes. It is found 
that the charge is positive and inversely proportional 
to the radius of the drops. This result follows if we 
assume that there is a constant charge produced per 
unit area of new water surface formed. The value 
of this constant is approximately 2°7x 107° electro- 
static units for distilled water, the splashing and 
spraying methods giving identical results.—W. G. 
Duffield : Effect of pressure upon arc spectra. No. 5.— 
A. Campbell and D. W. Dye: The measurement of 
alternating electric currents of high frequency. As 
the accurate measurement of currents larger than 
I ampere at high frequencies presents considerable 
difficulty, the authors have investigated the accuracy 
obtainable in the use of air-core current transformers 
(suggested by Mr. T. L. Eckersley). It is found that, 
' with proper design, such transformers allow of the 
measurement of currents up to 50 amperes or higher, 
at frequencies from 50,000 up to 2,000,000 per second, 
with an accuracy of 1 or 2 parts in 1,000. Over the 
same range of frequency it is also found that iron- 
cored transformers can easily be designed so as to 
give very accurate results.—Sir D. Bruce, Maj. A. E. 
Hamerton, Capt. D. P. Watson, and Lady Bruce: 
(1) The trypanosome causing disease in man in Nyasa- 
land. The Liwonde strain. Part i.—Morphology. 
Part 1i.—Susceptibility of animals. (2) The naturally 
infected dog strain. Part ii—Morphology. (3) Sus- 
ceptibility of animals to the naturally infected dog 
strain. (4) Morphology of various strains of the 
trypanosome causing disease in man in Nyasaland. 
The human strain. vi.—x. (5) The trypanosome 
causing disease in man in Nyasaland. ii.—The wild 
game strain. iiii—The wild Glossina morsitans 
strain. Part 1i.—Susceptibility of animals. (6) The 
naturally infected dog strain. Part iii. Development 
in Glossina morsitans. (7) The naturally infected dog 
strain. Part iv—Experiments on immunity.—Dr. F. 
Horton: The origin ot the electron emission from 
glowing solids.—W. A. D. Rudge: Some sources of 
disturbance of the normal atmospheric potential 
gradient.—Prof. J. Joly: A theory of the nature of 
cancers and of their treatment by radio-therapy.— 
| C. S. Mummery: Morphological studies of benzene 
derivatives. VI.—Parasulphonic derivatives of chloro-, 
