196 
SCIENTIFIC SUMMARY. 
ASTRONOMY. 
mHE Deduction of the Mean Figure of the Farth from comparison of the 
-JL Anglo-Gallic, Russian, and Indian Arcs, is the subject of a communi- 
cation transmitted to the Philosophical Magazine for February, by Archdeacon 
Pratt. The paper is one of the highest importance ; but as the details are 
of too mathematical a nature for these pages, we merely call attention to 
the fact of the publication of the essay. Those especially interested can 
peruse the original memoir themselves. 
The Solar Spectrum. — M. Angstrom in a memoir recently published, calls 
attention to two important results arrived at from his researches. The first 
is the certain presence of manganese in the sun, he having observed the 
coincidence of at least thirty lines. The other is the discovery of a new 
hydrogen line. The spectrum of hydrogen, presents, as is well known, three 
lines — two of which coincide with C and F, and a third with a line near G. 
The fourth line which M. Angstrom has observed is near the middle of the 
interval between G and H ; it coincides with a very intense solar line, which 
he has called h. With Geissler’s tube this line is very distinctly seen, 
although it is very much less feeble than the three others. This result is 
the more satisfactory, as the line h was the only one among those of a 
certain intensity, whose origin still appeared mysterious. The explanation 
of it which M. Angstrom has found in the spectrum of hydrogen, acquires 
an additional interest from the fact that the line h occurs several times in 
the stellar spectra, drawn by Mr. Huggins. 
The cause of the Heat of the Sun and Heavenly Bodies . — On March 4, M. 
Patau called the attention of the French Academy to his memoir on the 
above subject. The memoir, however, has not yet been laid before the 
members. 
The Solar Spots . — Herr Kirchhoff has published a reply to M. Faye, 
relative to the course of the solar spots. He says, whatever be the consti- 
tution of the sun, the spots can only be explained by a local diminution of 
temperature approaching or exceeding incandescence. “My hypothesis 
supposes the cause of this diminution to lie in the radiation of clouds, 
toward planetary space, of clouds produced by the condensation and isola- 
tion of the photosphere.” Herr Kirchhoff admits that possibly other ex- 
planations of the cooling process, may better meet all the facts of the case, 
but he considers that the adoption of any of them which rejects the con- 
sideration of a diminution of temperature would be equivalent to asserting 
the natural law3 are quite different on the sun to what they are on the 
surface of the earth . — Comptes Rendus , March 4. 
