up and down so that the field swept the neighbourhood of the estimated
point of apparition. I need hardly say that Mercury did not appear
exactly at the assigned point, nor did I see him make his first
appearance; but I picked him up so soon after emergence that the outline
of the house was in the field of view with him. He appeared as a
half-disc. I followed him with the telescope until the sun had set, and
soon after I was able to see him very distinctly with the naked eye. He
shone with a peculiar brilliance on the still bright sky; but although
perfectly distinct to the view when his place was indicated, he escaped
detection by the undirected eye.[12]

Mercury does not present any features of great interest in ordinary
telescopes; though he usually appears better defined than Venus, at
least as the latter is seen on a dark sky. The phases are pleasingly
seen (as shown in Plate 6) with a telescope of moderate power. For their
proper observation, however, the planet must be looked for with the
telescope in the manner above indicated, as he always shows a nearly
semi-circular disc when he is visible to the naked eye.

We come next to Venus, the most splendid of all the planets to the eye.
In the telescope Venus disappoints the observer, however. Her intense
lustre brings out every defect of the instrument, and especially the
chromatic aberration. A dark glass often improves the view, but not
always. Besides, an interposed glass has an unpleasant effect on the
field of view.

Perhaps the best method of observing Venus is to search for her when she
is still high above the horizon, and when therefore the background of
the sky is bright enough to take off the planet's glare. The method I
have described for the observation of Mercury will prove very useful in
the search for Venus when the sun is above the horizon or but just set.
Of course, when an object is to be looked for high above the horizon,
the two rods which support the cross-rods must not be upright, but
square to the line of view to that part of the sky.

But the observer must not expect to see much during his observation of
Venus. In fact, he can scarcely do more than note her varying phases
(see Plate 6) and the somewhat uneven boundary of the terminator. Our
leading observers have done so little with this fascinating but
disappointing planet, that amateurs must not be surprised at their own
failure.

I suppose the question whether Venus has a satellite, o