When Mercury shows himself at eastern elongation, he may be seen in the west as an evening star for somewhere near a week, each evening drawing nearer to the sun. When he disappears from view he passes between us and the sun, and about four weeks later appears in the morning sky before the sun rises. Under favorable conditions he is again visible for a week or more; and then, again approaching the sun, he can be seen no more for about ten weeks, during which time he passes through superior conjunction on the other side of the sun from us and comes back to eastern elongation. Thus we can get, under very favorable conditions, six short views of Mercury during the year--three in the evening and three in the morning. So many views, however, are rarely secured by any but the professional observer. The circumstances may well be considered felicitous if one succeeds in getting a glimpse of him once or twice a year--at his favorable situation in the evening in the spring and the morning in the autumn. The sight of him, though, is truly worth a little inconvenience--even to the extent of facing a cold evening wind in the very early spring or getting out of a comfortable bed before dawn during the first cool mornings of autumn. It is hardly possible to say exactly where one can find Mercury at all times during a long succession of revolutions. Moreover, it is not necessary. These computations are made anew each year by experts in the employ of the government, and the result is published in the _Nautical Almanac_. From there it finds its way into all almanacs, so it is easy of access to any one. In the almanacs Mercury is represented by the sign (☿). It is a conventionalized form of the caduceus, or wand, carried by the god Mercury as a symbol of his power. The next seven eastern and western elongations of Mercury occurring after the publication of this book are as follows: Eastern Elongation Western Elongation (Evening Star). (Morning Star). 18 November, 1912. 27 December, 1912. 10 March, 1913. 24 April, 1913. (Favorable for viewing.) 7 July, 1913. 22 August, 1913. (Favorable for viewing.) 1 November, 1913. 10 December, 1913. 22 February, 1914. 6 April, 1914. (Favorable for viewing.) 18 June, 1914. 5 August, 1914. (Favorable for viewing.) 15 October, 1914. 23 November, 1914. DISTANCE AND BRIGHTNESS