322 Mr. Schroeter's Observations 
cannot be said, like the moon, to receive some light upon its 
dark side from our earth, or any other heavenly body, it follows 
that this light must either proceed immediately from the sun, 
which, as I have frequently observed concerning the high 
mountains Leibnitz and Doerfel in the moon,* throws its rays 
directly on the tops of very lofty ridges of mountains; or else 
that it is a light which partly illuminates the atmosphere of 
Venus, and partly, being reflected by this atmosphere, marks 
out by a faint glimmer the limb of the dark hemisphere of the 
planet, in the same manner as our morning and evening 
twilight acts upon ours. 
All our present observations militate against the supposition 
of this phenomenon being the effect of light immediately pro- 
ceeding from the sun; for, 
1. This light does not appear, as on the mountains Leibnitz 
and Doerfel in the moon, in single, detached, and distant points ; 
but as a continued streak of light, proceeding from the extre- 
mities of the cusps, and continuing along the limb of the dark 
hemisphere to a distance of about 8", or, in proportion to the 
apparent diameter of the planet, no less than 15 0 19' of its cir- 
cumference. This light also, compared with the bright part 
of the phase, is not unlike the comparatively pale limb of the 
dark part of the moon before and after its conjunction. 
2. Were this the light of the illuminated summits of a chain 
of mountains, it would not appear so even, regularly con- 
nected, and spherical, as we behold it. But what removes all 
manner of doubt is, 
s. 
3. The very different, extremely faint, bluish ash-coloured 
appearance of this glimmering light, which forms as great a 
* See Selen. Frag. § 75. and Tab. IV. fig. 6 and 8. 
