354 Afr. Schroeter’s Observations 
natural for me, after the successful observations I had made on 
the twilight of the moon, to pay particular attention to this 
circumstance. On the 25th February, at 6 h P. M. the sky be- 
ing very clear, the limb of the dark part of the moon appeared 
uncommonly distinct ; and only a few seconds of a degree from 
its edge was seen a telescopic star, of about the 10th or 12th 
magnitude. I counted full 20" before its occultation, and 184 
of these, without the least perceptible diminution of light. 
The star, however, began now gradually to fade, and after 
the remaining during which I observed it with all pos- 
sible attention, it vanished in an instant. This observation 
agrees perfectly with the above computations. Although it 
be proved that the inferior dense part of the lunar atmo- 
sphere reflects a stronger light than that which the dark he- 
misphere receives from an almost fully illuminated disk of our 
earth ; and although, considering the inferiority of gravitation 
on the surface of the moon, there be no doubt that this dense 
part, together w'ith the superior gradually more rarified regions 
of its atmosphere, must extend far above its highest mountains ; 
it is yet a fact that the breadth of this observed twilight, to where 
it loses itself in our reflected terrestrial light, does not measure 
more than 2 0 34' : it is, therefore, highly probable that its 
greatest extent, in the most favourable phases near our new 
moon, can never exceed the double of the above arc, or 5 0 8' ; 
and hence we can only infer a perpendicular height of an at- 
mosphere, capable of inflecting the solar rays, which at most 
measures 537b feet : nor is it very likely that, unless accidental, 
and hitherto unknown circumstances should occasionally con- 
dense different parts of this atmosphere, these upper strata should 
materially affect the distinctness of a star seen through it. 
