☉ The Sun ☿ Mercury ○ Full Moon ♀ Venus ☾ Last Quarter ♁ The Earth ● New Moon ♂ Mars ☽ First Quarter ♃ Jupiter ☌ Conjunction ♄ Saturn ☍ Opposition ♅ Uranus ♆ Neptune _Conjunction._--When this sign is used it means that two planets, or the Sun and a planet, or the Moon and a planet, are on the _same_ side of the Earth. _Opposition._--When this sign is used it means that two planets, or the Sun and a planet, or the Moon and a planet, are on opposite sides of the Earth. To see how these signs work out suppose you look up the month of January, 1915, in an almanac. The first line, besides showing that it is the first day of the year, the first day of the month and that it is Friday, also shows that the ○ (Moon) is full. It further gives the time the ☉ (Sun) rises and sets, the length of the days in hours and minutes, the ○ (Moon’s) age in days, and when it rises and sets. Then on the same line the following signs are given: ♂ ☿ ☌ and this means that a conjunction of Mercury and Mars will take place on this date; that is, that they will be nearer to each other from our line of sight than at any other time for a long while. On the next line, which is the 2nd of January, the following signs are given: ♀ _greatest brilliancy_; ♁ _in perihelion_ ☌ ♆ ☾; the first of which means that Venus has reached its greatest brightness; the second, that the Earth is the nearest to the Sun that it will get, and the third, that there is a conjunction of Neptune and the Moon; and so on for every day of the year. _Note_: A good almanac for daily star information is the _Old Farmers’ Almanac_, a copy of which you can get by sending 11 cents to William Ware and Company, Boston, Mass. CHAPTER XII VALUABLE INFORMATION =Photographing the Stars.=--There are some interesting things you can do with an ordinary _camera_ in the way of photographing the stars. A camera is made up of three principal parts, and these are (1) a convex lens, which forms the image of the object to be photographed; (2) a light-tight box, which keeps out all the light except that which passes through the lens, and (3) a plate, or film holder, which holds the sensitive plate, or film, in the camera and keeps it perfectly dark until you are ready to have the image formed on it. The instant the lens is allowed to form an image on the _sensitive plate_, or _film_, we get out of the _optics_ of photography and into the _chemistry_ of it. The sensitive plate, or film, is coated with a thin layer of salts of silver and bromide, heated with gelatine and a little water, and when these substances are thoroughly mixed, an _emulsion_ results, and this is spread on glass plates or on celluloid films. When the plate is exposed, that is, when the image has been formed on it, it is developed. The developing is done by placing the plate in a solution of _pyrogallic acid_, or _hydroquinone_ and water.