SCIENTIFIC SUMMAKY. 
445 
The late Lunar Eclipse. — A partial eclipse of tlie Moon took place on tlie 
13th. of September. It commenced at about twenty minutes to ten. The 
following was the order of appearances : — 
h. m. 
First contact with the penumbra 9 43-3 Greenwich mean time. 
First contact with the shadow . 10 57*4 
Middle of the eclipse . .12 26-2 
Last contact with the shadow . 13 55 -0 
Last contact with the penumbra 15 9T 
Magnitude of the eclipse (Moon’s diameter=l), 0693. 
Aqueous Vapour in the Stars. — M. Jansenn announces an important dis- 
covery which he has just made — viz., that in a spectrum-analysis of some of 
the stars, he has seen bands which indicate the presence of aqueous vapour 
in these bodies. He observed this especially in the case of the spectrum of 
Antares. In order to avoid any error through the presence of atmospheric 
vapour, M. Jansenn conducted his experiments at Etna, where the air is 
remarkably rare and dry. Researches made at Palermo and Marseilles 
lead him to conclude that there is water-vapour in the atmosphere of both 
Mars and Saturn. 
The labours of the Lunar Committee have formed the subject of some 
interesting comments by Mr. Glaisher. The method in which the work is 
distributed among the several observers is admirably adapted to meet the 
ends aimed at by the Committee. The areas are divided into subzones of 1 
deg. of latitude, and they are allotted to observers in such a way that, by 
each pair overlapping and dovetailing into the adjoining pairs, every object 
shall be brought under the eyes of two independent students. It is 
proposed that the returns which the Committee may receive shall be ex- 
amined by Mr. Birt, with the aid of a telescope of superior power, after 
which the state of the objects so examined is to be regarded as authorita- 
tively fixed for the epoch of examination. The most difficult part of the 
study of the Moon’s surface is that of delineation. No two drawings of the 
same object will ever agree in all the details, and a series of drawings of the 
same object will manifest very considerable departures from one made at 
the period of mean libration, which occurs once only in three years. In 
arranging the formulae for the computation of the librations of the centre of 
the apparent disc, Professor Challis, of Cambridge, has rendered this Com- 
mittee essential service. In preparing Appendix II. in the last volume of 
reports, which includes libration, Mr. Birt has given (from tbe Berliner 
Astronomisches Jahrbuch fur 1843), the derivation, as arranged by Professor 
Challis, of the Formulae for Libration, inserted on p. x. of the Nautical 
Almanac, and also the formulae employed by Lohrmann in the computation 
of points of the first order, including those for libration. The difficulties 
attendant upon the delineation of the surface being so great, the Committee 
has not ventured beyond the simple outline of the two areas already issued. 
The Crater LJnne. — The observations upon this singular crater which have 
been made from December 12, 1866, up to June 11, 1867, have now 
been published, and show how advanced is our knowledge of seleno- 
graphy. As Mr. Birt stated at the British Association, three features in 
