i879-1 
Proceedings of Societies. 
821 
fossils brought home were sent to Mr. Etheridge for examina- 
tion, the birds and eggs to Mr. Fielden, while the plants were 
sent to Dr. Hooker and Mr. Oliver. A discussion followed in 
which Count Bylandt, Sir Leopold M‘Clintock, Sir George 
Nares, and Admiral Hamilton took part. 
Paris. 
Academy of Sciences, November 3. — The memoirs presented 
at this meeting included the following : — 
“ Result of the Researches made for the purpose of Disco- 
vering the Origin of Re-invasions of Phylloxera."— M. Faucon. 
— The author contends for the superiority of immersion to 
insecticides. The method he indicates is as follows : — On heavy 
lands, which hold water well, the immersion should be continued 
for 55 consecutive days ; on moderately light soil, for 65 days ; 
and on very light land, for 75 days. If the immersion is intended 
to destroy the eggs of Phylloxera , it must be carried on without 
the least interruption for 90 days on medium, and for 120 days 
on light, lands. 
“A New Stellar Spectroscope.”— M. L. Thollon. — M.Thollon 
has arrived at the conclusion that, in order not to repeat indefi- 
nitely experiments already made, three things are necessary, 
viz. : — (1.) That the place of observation should be as high as 
possible, and in a very favourable climate. (2.) That the greatest 
possible quantity of light should be concentrated on the slit of 
the spectroscope by means of an objeCt-glass or a mirror with a 
broad surface. (3.) That a spectroscope should be used in which 
the loss of light is reduced as much as possible. It is to the 
solution of the latter problem that M. Thollon has specially 
direCled his attention. He calculates the loss of light in an 
ordinary spectroscope to at least 57 per cent. The instrument 
he has invented contains two compound direCt-vision prisms of 
special form, one in the collimator, the other in the telescope 
tube. The larger of the simple (or component) prisms has an 
angle of ioo°, and contains a mixture of sulphide of carbon and 
ether. Two rectangular prisms of crown glass, one on either 
side, have faces parallel to each other and to the bisecting line 
of the angle of ioo°. With this spectroscope M. Thollon has 
succeeded in economising light, and, to a certain degree, in 
making up for the loss that cannot be avoided. 
