_Thoth-Nepenthes_, peculiar course of, 208; hibernation of, 315-324. _Titan_, 305. Triassic era, 136, 142, 152. _Trivium Charontis_, canals and oases in, 251, 252, 256. Twilight arc, shows thin air, 85, 162. Uranus, 33. Vegetation, 79, 119-127, 163, 166, 169, 301; color of Mare Erythraeum, 122-126; proof of, 170; theory supported by rifts in polar cap, 329; most satisfactory explanation of phenomena of canals, 339, 341, 344, 345, 347, 348, 373; two seasons of growth of, 346; melts snow, 328. Water, dearth of, 128, 161, 163, 166, 168, 169, 341, 366; loss of, inevitable, 131; speed of flow of, 375; from polar caps, 340, 374. Water-vapor, from polar caps, 83; in atmosphere, 162, 168. Weather, 66, 89, 95. _Wedge of Casius_, 242; canals in, 247; oases in, 251, 252, 256. Welkin, man-manufactured, 13-15. White spots, 32, 165; similar in look to polar caps, 73; location and season of, 74, 76-79, 80, 81; White spots, permanency of, 73, 76; indication of temperature, 80, 165. Winds, 154. Winter, Martian, 35, 48. World, Mars another, 4, 5, 169; evolution of a, 16, 128, 131, 155-158, 358. Year, of Earth, 35; of Mars, 35, 161. A COMPENDIUM OF SPHERICAL ASTRONOMY With its applications to the determination and reduction of positions of the fixed stars By SIMON NEWCOMB Cloth 8vo $3.00 net -------------- CONTENTS PART I. PRELIMINARY SUBJECTS CHAPTER I. INTRODUCTORY. NOTES AND REFERENCES. CHAPTER II. DIFFERENCES, INTERPOLATION, AND DEVELOPMENT. NOTES AND REFERENCES. CHAPTER III. THE METHOD OF LEAST SQUARES. Section I. Mean Values of Quantities. II. Determination of Probable Errors. III. Equations of Condition. NOTES AND REFERENCES. PART II. THE FUNDAMENTAL PRINCIPLES OF SPHERICAL ASTRONOMY CHAPTER IV. SPHERICAL COÖRDINATES. Section I. General Theory. II. Problems and Applications of the Theory of Spherical Coördinates. CHAPTER V. THE MEASURE OF TIME AND RELATED PROBLEMS. Section I. Solar and Sidereal Time. II. The General Measure of Time. III. Problems Involving Time. CHAPTER VI. PARALLAX AND RELATED SUBJECTS. Section I. Figure and Dimensions of the Earth. II. Parallax and Semi-diameter. CHAPTER VII. ABERRATION. CHAPTER VIII. ASTRONOMICAL REFRACTION. Section I. The Atmosphere as a Refracting Medium. II. Elementary Exposition of Atmospheric Refraction. III. General Investigation of Astronomical Refraction. Notes and References to Refraction. CHAPTER IX. PRECESSION AND NUTATION. Section I. Laws of the Precessional Motion. II. Relative Positions of the Equator and Equinox at Widely Separated Epochs. III. Nutation. Notes and References to Precession and Nutation.