PREFACEDuring the past few years the subject of variable stars has become increasingly interesting to the amateur who is the owner of a telescope, as well as to the average college student who has some knowledge of astronomy, while to the research worker it offers many lines of investigation which are full of promise. However, so complex is the subject, and so diverse the principles involved in a complete understanding of it, that extensive reading in several different directions is required as a foundation.It is with the purpose of supplying this need as well as of making an important and attractive branch of astronomy accessible to the student that the present volume has been prepared. It is the outcome of several years of teaching the subject in Vassar College, for which the material was primarily collected. This material is scattered throughout various periodicals in the form either of research papers or quite popular articles, intended to give directions for observation to ownTable of Contents CONTENTS; I INTRODUCTORY; General description of stellar variation Elements of variation Julian Day Classification of variables Principles of spectrum analysis Classification of stellar spectra Connection between spectral type and type of variation 3; H STAR CHARTS FOR GENERAL USE; Argelander, Uranometria Nova Heis, Atlas Coelestis Schurig, llimmels Atlas Upton, Klein, etc Argelander, Bonner Durckmusterung, detailed account, with suggestions for its use Palisa and Wolf, photographic maps Ecliptic charts Charts of Carte du CieL Precession 88; m STAR CHARTS FOR VARIABLES; Hagen, Atlas StcUarum Variabilium, very detailed account, with directions for its use Parkhurst, enlargements Harvard photographic maps Miscellaneous 52; IV CATALOGUES OF VARIABLES; Naming of variables Harvard, Hartwig, Chandler Methods of discovery; visual, photographic, spectroscopic Illustrations Systematic search 68; V STELL