What the telescope does with Epsilon Lyræ, it does with a great multitude of other stars. There are thousands of doubles of all degrees of easiness and difficulty--doubles wide apart, and doubles so close that only the finest telescopes in the world can separate them; doubles of every degree of likeness or of disparity in their components, from Alpha Geminorum (Castor), with its two beautiful stars of almost equal lustre, to Sirius, where the chief star is the brightest in all the heavens, and the companion so small, or rather so faint, that it takes a very fine glass to pick it out in the glare of its great primary. The student will find in these double stars an extremely good series of tests for the quality of his telescope. They are, further, generally objects of great beauty, being often characterized, as already mentioned, by diversity of colour in the two components. Thus, in addition to the examples given above, Eta Cassiopeiæ presents the beautiful picture of a yellow star in conjunction with a red one, while Epsilon Boötis has been described as 'most beautiful yellow and superb blue,' and Alpha Herculis consists of an orange star close to one which is emerald green. It has been suggested that the colours in such instances are merely complementary, the impression of orange or yellow in the one star producing a purely subjective impression of blue or green when the other is viewed; but it has been conclusively proved that the colours of very many of the smaller stars in such cases are actual and inherent. Not only are there thousands of double stars in the heavens, but there are also many multiple stars, where the telescope splits an apparently single star up into three, four, or sometimes six or seven separate stars. Of these multiples, one of the best known is Theta Orionis. It is the middle star of the sword which hangs from the belt of Orion, and is, of course, notable from its connection with the Great Nebula; but it is also a very beautiful multiple star. A 2-1/2-inch telescope will show that it consists of four stars in the form of a trapezium; large instruments show two excessively faint stars in addition. Again, in the same constellation lies Sigma Orionis, immediately below the lowermost star of the giant's belt. In a 3-inch telescope this star splits up into a beautiful multiple of six components, their differences in size and tint making the little group a charming object.