On a clear night points of starlight seem to fairly fill the sky, yet it will be found, on careful examination, that the brightest of them often seem to be assembled together in a very picturesque manner, forming the outlines of figures such as the Dippers, the Crown, the Cross, the Sickle or the Lyre. Since these designs unfailingly deck the heaven's dome at the same place, hour and season each year, there is not the hopeless confusion among the stars that the novice might think from his occasional glances at the sky. These star groups, or constellations, were probably first noted and named in Chaldea where the ancient shepherds amused themselves by tracing their heroes among the stars. One can well imagine the hold that these dream-pictures would have on a lonely shepherd as he wandered about the solitudes of the hills and gazed through the quietness of the night at the distant stars. For long ages these stories were told by one shepherd to another and so vivid were their fancies and so keenly were they enjoyed that they made an indelible impress upon the folk-lore of other nations and in this manner have been carried down to the present day. The stars are self-luminous, like our sun,--indeed, the stars are distant suns, and the sun is a nearby star. With the exception of the star or sun around which the earth and the other planets of our solar system whirl, all the other suns are so immensely remote from the earth that their huge diameters dwindle to a mere twinkle of light. The diameters of some of the stars have been measured and have been found to vary from a few thousand miles to many million miles. Our sun, a most medium sized star, has also been measured and has a diameter of 866,000 miles; this diameter, as seen from any other system of planets, would also dwindle to a twinkle, and our great sun would thus be lost among the other stars. Throughout the sky are young stars, adult stars, and stars whose light has almost flickered out, for stars, we find, even as all other things in Nature, have a limited span of life. This life may last for untold ages but as surely as stars are formed, so do they die. The nucleus of a star is formed by gas under high pressure. This gas is gathered together by the force of gravity and gradually condensed into a glowing ball. In contracting the stars at first rise in temperature but when too advanced condensation retards this contraction, then the star gradually cools.