SCIENTIFIC SUMMARY. 
199 
the diffraction disc on the one side (towards the moon), and intact on the 
other. The explanation given by Mr. Christie seems sound. “ The star 
was not bright enough to he seen distinctly projected on the moon’s disc, 
hut was yet not so faint as to he overpowered hy the irradiation at the limb. 
A spurious limb being formed by the superposition of diffraction images, the 
inferiority of light would increase gradually from the spurious to the true limb. 
At the former, the star’s light overpowered that of the moon ; at the latter, 
the moon’s light overpowered that of the star.” The circumstance that the 
diffraction image of the star was completely cut off on the side of the moon 
at the instant of its disappearance is strikingly confirmatory of this expla- 
nation. 
A Strange Mistake. — Oddly enough Mr. Christie has allowed a remarkable 
mistake to appear in a paper which he edits. Messrs. Hirst and Russell, 
observing the moon at nine in the morning of October 21, the moon being 
then past her third quarter, imagined they saw a great circular shade (or 
rather part of such a shade) on the moon’s face. Mr. Russell inquires into 
its possible nature, gravely discussing whether it may not have been the 
shadow of some unknown opaque globe, or of a very dense comet, between 
the earth and the sun. In reality the supposed shade was nothing but what 
can always be recognised when the moon is at that phase, the outline of 
certain dark seas forming in appearance, at that time, a part of a great 
circle having an apparent radius equal to nearly three-fourths of the 
moon’s. 
Phenomena for the Quarter . — Mercury will be in inferior conjunction with 
the sun on April 17, at 1 1 a.m. ; at his greatest westerly elongation on 
May 15, when he will be 25° 40' west of the sun ; and at superior conjunction 
at midnight June 18. Venus is an evening star all through the quarter, her 
distance from the sun and her brightness increasing through the quarter, the 
former, indeed, not attaining a maximum till the middle of July, the latter 
not till the middle of August. The proximity of Mars and Saturn at the 
end of June will render these planets interesting objects to telescopists, 
though Mars will be far less brilliant than when he was in conjunction with 
Saturn in the autumn of 1877. At 8 p.m., June 80, the distance between 
the planets will not be more than one minute — a thirtieth, say, of the moon’s 
diameter. But it will not be till a much later time of that night that the 
proximity of the planets can be favourably observed in England. 
CHEMISTRY. 
Conversion of Sugar into Alcohol by Inorganic Agents. — While considering 
the action of fermenting agents, Berthelot has been led to try an experiment 
which does not exactly solve the question of the conversion of sugar into 
alcohol by inorganic agents, although it throws some light upon that change. 
The hypothesis, to follow the consequences of which was of interest to him, 
was the following. If we assume that the action of a ferment consists in 
the breaking up into two complementary ingredients, of which the one con- 
tains the more oxygen, the other the more hydrogen — an action, in short, 
elosely resembling that of potash on aldehyde — the two products will exhibit 
