NovEMBER 26, 1896] 
NATURE 
Sia: 
yerse vibrations, at any rate if the surfaces of equal refractive 
index are parallel planes. Dr. Garbasso does not seem, how- 
ever, to introduce any considerations of the ‘‘ Hall effect” into 
his calculations ; whether the latter phenomenon has any bearing 
on the question or not, is quite another matter. 
Dr. E. ODDONE has recently examined the seismic record of 
Liguria during the last century (1796-1895), in order to determine 
whether the frequency of earthquakes in that district is subject 
to any periodic laws. The record is a non-instrumental one, 
and the results derived from it have not therefore the same value 
as those obtained from a seismometric catalogue. Dr. Oddone 
shows that the supposed nocturnal prevalence of earthquakes is 
here insensible, but there is a daily period with its maximum 
between 6and7a.m. The two halves of the century do not 
exhibit the same distribution of earthquakes throughout the 
year, and in the latter half (during which the record is most 
complete}, earthquakes are equally numerous in the summer and 
winter months. They are less frequent during years of maximum 
solar activity, and vce versd, so that there appears to be a period 
of eleven years, and possibly also one of about twice this length. 
WE have received a work on Earth Temperatures at Mustiala, 
by Dr. T. Homén, being part 9, vol. xxi. of the Acéa of the 
Society of Sciences of Finland. The Agricultural Institute of 
Mustiala is situated in lat. 60° 49’ N., and long. 23° 47’ E.; the 
observations were taken both near the Institute and atthe woody 
district of Heinais, about seven miles to the north, during the 
years 1885-94, at various depths, and are printed 7 extenso, 
together with monthly means and yearly extremes. They are 
discussed with a view to showing the influence of rainfall and 
snow-covering upon the temperature of the earth, and are also 
compared with similar observations at Pavlovsk and St. Peters- 
burg. The first regular observations of earth temperature in 
Finland were made at Sodankyla during the international polar 
expeditions of the years 1882-4 ; the present work, therefore, 
fills an important gap in the knowledge of the natural phenomena 
of that country, and will, no doubt, repay the large amount of 
careful labour bestowed upon it. 
Pror. W. H. Jutius has devised a very neat apparatus for 
eliminating all small moyements due to vibrations from delicate 
instruments, such as galvanometers, &c. Last year (in the Wied. 
Ann., 56, p. 151) he described this method, and a note on the 
subject was made in these columns (NATURE, vol. lii. p. 578). 
Quite recently he has given an account of a modified form ot ap- 
paratus into which instruments to be shielded from these vibra- 
tions can be placed. This apparatus consists practically of a kind 
of framework, suspended by three wire cords, into which the 
instrument to be used is placed. It is found that, under these 
conditions, vibrations which otherwise would have disturbed the 
instrument are nearly eliminated. There are, however, certain 
conditions to be fulfilled to reduce such vibrations toa minimum ; | 
for instance, it is advisable so to arrange the centre of gravity of 
the whole apparatus, with the instrument included, that this 
point should fall in the plane in which the three lower extremities 
of the wires are connected to the framework. Further, if there 
be any special point in the instrument in question which must be 
shielded from any influence or vibration—such as, for instance, 
the quartz or silk thread of a galvanometer—this point should 
also be brought into the same plane. The apparatus which 
Prof. Julius has devised is arranged to fulfil these requirements. 
It consists of three rods placed parallel to one another in 
triangular form, and coupled together at their extremities by 
two metal hoops. This framework is suspended by three metal 
wires, the latter extremities of which are fixed to it at three 
points near their middle parts, lying ina plane between two 
hoops, referred to above ; a third hoop is placed which can slide 
lengthways along the three rods. It is on this that the instru- 
ment to be freed from vibrations is placed. To bring the whole 
NO. 1413, VOL. 55 | 
centre of gravity toa point in the plane of the three points of 
suspension, the framework is suspended horizontally temporarily 
by one of the wires ; and the balance of the apparatus, with the 
mstrument attached, is obtained by varying the position of the 
three weights placed near the ends of the rods for that purpose. 
The adjustment of that special part of the instrument which 
must be freed from vibration, is made by placing this, as near as 
possible, at the centre of gravity. To deaden any movements in 
the whole apparatus, three fan-shaped appendages are fixed to 
the hooks to which the wires are attached, and these are intended 
to be immersed in vessels filled with paraffin. The apparatus 
itself seems, from all accounts, to overcome the difficulties 
occasionally met in freeing delicate instruments from minute 
tremors. After being once accurately suspended, the chief 
difficulty in its adjustment is practically at an end. Supplied 
with the apparatus is also a small bracket, which can be fixed 
to the ceiling or beam, from which the apparatus can be 
suspended. 
Mr. G. CG; WurepLe reprints from the Zechnology Quarterly 
(Boston, U.S.A.) an interesting paper on the growth of diatoms, 
especially in relation to the purity or impurity of drinking water. 
An abundant food supply is not the only favourable condition 
for the rapid increase of diatoms; temperature, the amount of 
light, and other conditions also influence their growth. In 
common with other chlorophyllaceous plants, they will not 
grow in the dark; while, on the other hand, bright sunlight 
kills them. The intensity of the light below the surface of the 
water being influenced by the colour of the water, diatoms are 
found most abundantly in light-coloured waters. Different genera, 
however, present differences in this respect ; J/e/oszra does not 
require so much light as Syeda. The weather has a marked 
influence on their growth. They increase most rapidly during 
those seasons of the year when the water is in circulation 
throughout the vertical. During these periods, not only is food 
material more abundant ; the vertical currents keep the diatoms 
near the surface, where there is light enough to stimulate their 
growth, and where there is abundance of air. Some species of 
diatom display very strong heliotropism, moving towards the 
source of light. 
Tue two latest additions to the Encyclopédie Scientifique 
des Aide-Mémoire are :—‘‘ Les Accumulateurs électriques,” 
by F. Loppe, and *L)Eclairage : Felairage électrique,” by 
Prof. J. Lefevre. The volumes set forth clearly and well the 
principles which have their applications in those branches of 
electrical engineering expressed by the titles. 
Ar the Royal Victoria Hall on December 1, Dr. W. D. 
Halliburton, F.R.S., will lecture on ‘‘ Painlessness,’”’ in com- 
memoration of the jubilee of the discovery of anzesthetics ; and 
on December 8, Dr. W. F. Hume will take ‘* From the Crimea 
to Baku” as the subject of a discourse. A few months ago 
(vol. liv. p. 232) Dr. Hume contributed an account of the great 
oil region of Baku to these columns. 
THE experiments of M. H. Bazin ‘‘ upon the contraction: of 
the liquid vein issuing from an orifice, and upon the distribution 
of the velocities within it,” clearly advanced the knowledge of 
the important and difficult question of the liquid vein. The 
memoir, in which the investigation was described, has been 
translated by Mr. John C. Trautwine, and published by Messrs. 
John Wiley and Sons. Hydraulic engineers and mathematical 
physicists will be glad to have this authorised translation in 
a handy volume form. 
Mr. W. Doserck, the Director of Hongkong Observatory, 
has sent us a copy of his report on the work done during 1895. 
All the typhoons—about 250—observed since the observatory 
was established in 1884, have now been investigated, and Mr. 
Figg, in conjunction with Mr. Doberck, is at present engaged 
