410 81. The Great Bear and Cassiopeia 411 82. The Great Square of Pegasus 413 83. Perseus and its Neighbouring Stars 415 84. The Pleiades 416 85. Orion, Sirius, and Neighbouring Stars 417 86. Castor and Pollux 418 87. The Great Bear and the Lion 419 88. Boötes and the Crown 420 89. Virgo and Neighbouring Constellations 421 90. The Constellation of Lyra 422 91. Vega, the Swan, and the Eagle 423 92. The Orbit of Sirius 426 93. The Parallactic Ellipse 444 94. 61 Cygni and the Comparison Stars 447 95. Parallax in Declination of 61 Cygni 450 96. Globular Cluster in Hercules 463 97. Position of the Great Nebula in Orion 466 98. The Multiple Star θ Orionis 467 99. The Nebula N.G.C. 1499 471 100. Star-Map, showing Precessional Movement 493 101. Illustration of the Motion of Precession 495

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THE

Story of the Heavens.

"The Story of the Heavens" is the title of our book. We have indeed a wondrous story to narrate; and could we tell it adequately it would prove of boundless interest and of exquisite beauty. It leads to the contemplation of grand phenomena in nature and great achievements of human genius.

Let us enumerate a few of the questions which will be naturally asked by one who seeks to learn something of those glorious bodies which adorn our skies: What is the Sun—how hot, how big, and how distant? Whence comes its heat? What is the Moon? What are its landscapes like? How does our satellite move? How is it related to the earth? Are the planets globes like that on which we live? How large are they, and how far off? What do we know of the satellites of Jupiter and of the rings of Saturn? How was Uranus discovered? What was the intellectual triumph which brought the planet Neptune to light? Then, as to the other bodies of our system, what are we to say of those mysterious objects, the comets? Can we discover the laws of their seemingly capricious movements? Do we know anything of their nature and of the marvellous tails with which they are often decorated? What can be told about the shooting-stars which so often dash into our atmosphere and perish in a streak of splendour? What is the nature of those constellations of bright stars which have been recognised from all antiquity, and of the host of smaller stars which our telescopes disclose? Can it be true that these countless orbs are really majestic suns, sunk to an appalling depth in the abyss of unfathomable space? What have we to tell of the different varieties of stars—of coloured stars, of variable stars, of double stars, of multiple stars, of stars that seem to move, and of stars that seem at rest? What of those glorious objects, the great star clusters? What of the Milky Way? And, lastly, what can we learn of the marvellous nebulæ which our telescopes disclose, poised at an immeasurable distance? Such are a few of the questions which occur when we ponder on the mysteries of the heavens.

The history of Astronomy