SCIENTIFIC SUMMARY. 
105 
PHYSICS. 
The Superficial Tension of Liquids considered in connection with certain 
movements observed on their surface, is the title of a memoir presented to 
the Royal Academy of Belgium by M. Van der Mensbrugghe, and published 
in the Bulletins for 1869. The paper is of particular interest for those who 
are acquainted with Mr. Tomlinson’s researches in this country. The move- 
ments described and explained in this memoir are such as those seen when 
a particle of camphor is placed on a surface of water. Such were explained 
by M. Dutrochet, on the supposition of a peculiar force, which he could not 
explain, and to which he gave the name of epipolic force. The author shows 
that this force is nothing more nor less than tension, and he proves his case 
by numerous experiments. Thomson had shown, as early as 1855, that the 
cause of the repulsion seen when a drop of alcohol was placed on water was 
the excess of tension of the latter ; but he confined himself to this one 
phenomenon. Dupre of Rennes, in 1867, showed that when one portion of 
a liquid is heated, it is drawn in all directions, simply by means of the dif- 
ference of tension thus produced. The author has extended these observa- 
tions very considerably, and has thus shown that a great variety of pheno- 
mena, hitherto unassociated, are really very closely allied. 
The Beversion Spectroscope. — A description of this curious instrument, by 
Herr Zollner appeared in Boggendorff s Annalen , Nov. 9, 1869. For the 
benefit of those who cannot read German comfortably, we may mention that 
a translation into French appears in the December number of the Archives 
des Sciences of Geneva. 
The British Meteorological Office. — We cannot hope for much advance in 
Physical Meteorology till better communication with other countries is esta- 
blished. Meantime, however, much is being done ; though there is yet a want 
of uniformity. In the report of the Meteorological Committee to the Royal 
Society it is stated that the system of telegraphy of storms to foreign 
countries is not uniform in its character. To the Marine Ministry in Paris 
the same messages are sent as to our own south coast and to J ersey. Hol- 
land and Hamburg receive special telegrams similar to those which are 
sent to the Underwriters’ Association of Liverpool. They convey the 
amount of atmospherical disturbance whenever the difference of readings 
over the same definite area exceeds 08 inch. The authorities at Hamburg 
hoist a drum at that port and at Cuxhaven whenever a telegram is received 
from London. These stations are thus precisely similar to those on our 
own coasts. In return for this intelligence immediate intimation is sent to 
London from France, Holland and Hamburg, by the meteorological authori- 
ties in their respective countries whenever a storm strikes any part of their 
coasts. The arrangements for telegraphy of storms to Italy have been in- 
terrupted by the lamented death of Professor Matteucci in the course of the 
year. 
The Spectrum of the Aurora. — It is interesting to note that, in confirma- 
tion of Angstrom’s researches, Mr. D. K. Winder, of the Toronto Astro- 
nomical Society, has found results closely allied to those of Angstrom’s. 
The report of the meeting of this society in October, which appears (with a 
