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444 NEW OBSERVATIONS OF THE PLANET MERCUKT. 
Crossing these two sets at angles of about 38 
of 
ones, in a general way 30° apart and in nearly equal numbers on opposite sides of the 
zero meridian, some six or seven running northwest and southeast across the disk, and 
about the same number running northeast and southwest. 
It might seem to be supererogatory to point out that this symmetry is on the 
planet, not elsewhere, as the lines that cause the symmetry turn with the planet. 
Before considering^ what this singular arrangement may betoken, certain other 
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features of the disk are to be noted. 
15. No Clouds. — The markings always show when their particular part of the 
planet is turned toward us, unless our own atmosphere at the moment be too bad. 
This invariable visibility of the markings is the first point to be remarked. For it 
shows that nothing near the surface of Mercury hides that surface from view. In 
other words, no clouds or mists or fog float between us and it. The surface lies bare 
to our gaze. 
16. Surface Colorless. — Next, that surface is colorless, the markings standing out 
in dark relief against the otherwise uniform pale white. Unlike Mars, with his 
beautiful opal-like tints, — rose-ochre and blue-green, — unlike the hues of the 
Earth seen from afar, — unlike even Venus, with her straw-colored veil, — Mercury 
shows a face as ashen as the Moon, a chiaroscuro in black and white. 
17. No Change. — No change ever sweeps over this face. The markings look at 
one time, apparently, just as they do at another. 
18. No Polar Caps. — There is no sign of white in the neighborhood of the 
poles. 
19. Atmosphere. — None of the effects which would follow upon the presence or 
an atmosphere are discernible ; nor were any evident during the observations at this 
Observatory when the planet crossed the Sun's face in November, 1894. If there be 
an atmosphere, it is thin. 
20. Surface Physical Characteristics. — From these observations stand disclosed 
the following physical features of the planet's surface ; (1) that nothing veils it in the 
way of clouds; (2) that it holds no appreciable atmospheric envelope : (3) that it has 
no polar snows; (4) that it contains no bodies of water; (5) that it supports no 
vegetation; (6) that no change takes place upon it; and that, in short, it is a dead 
world. The first point is proved by the continuous visibility of the markings ; the 
second, negatively by what I have stated above, and positively by the albedo of the 
disk and the loss on the terminator shown by micrometer measures of the diameters ; 
the third, by the absence of white at the poles ; the fourth and fifth, by the entire 
