1879.] 
( 8u ) 
PROCEEDINGS OF SOCIETIES 
Astronomical Society, Nov. 19.— Lord Lindsay, President, in 
the chair. 
Prof. Adams read a paper “ On the Ellipticity of Mars and its 
Effecft on the Motion of the Satellites.” He said that Prof. 
Asaph Hall’s observations showed that the orbits of both satel- 
lites are inclined at small angles to the plane of the planet’s 
equator. It became an interesting question to enquire whether 
this state of things is a permanent one. Mr. Marth had recently 
investigated the motion of the nodes of the orbits of the satellites 
on the orbit of the planet, which will be due to the disturbing 
adtion of the Sun, and he came to the conclusion that, if there 
is no force depending on the internal structure of Mars which 
modifies the Sun’s adtion, the nodes of the orbits will be in 
opposition to each other a thousand years hence. But Prof. 
Adams argued that this motion would be materially affecfted by 
the disturbing force due to the ellipticity of the planet, which 
would cause the nodes of the satellites to retrograde on the 
plane of the planet’s equator. The ellipticity of Mars is too 
small to be observed, but the motion of the nodes will probably 
afford a means of determining the ellipticity of the planet within 
very definite limits. 
Mr. Stone read a paper “ On the Evidence of a Past Connec- 
tion between four widely separated Southern Stars, viz., fTou- 
cani, e Eridani, f 1 Reticuli, and f 2 Reticuli.” 
Mr. Christie read a paper by Prof. C. J. Draper “ On a Photo- 
graph of the Solar Spedtrum, showing dark lines coincident with 
oxygen lines. 
Mr. De La Rue gave an account of a visit to the works of 
Messrs. Repsold, Hamburg, and described a conical pendulum 
for the driving-clock of an equatorial which was being made for 
Professor Winnecke, of Strasburg. The principle was similar 
to that of the balance-wheel and spring of a watch, for the elas- 
ticity of the rod of the pendulum was made use of instead of the 
force of gravity to resist the centrifugal force caused by the 
motion of the pendulum. Messrs. Repsold told him that when 
the driving weight of the clock was changed for another fifteen 
times as great, the variation and the rate of rotation only 
amounted to 0-04 per cent. 
Dr. Schuster read a paper “ On the Polarisation of the Co- 
rona.” 
The President said he had obtained an observation of Deimos 
at Dunecht. Mr. Christie also obtained observations of Deimos 
at Greenwich, made on the 4th and 18th of October. 
3 F 2 
