Page:Popular Science Monthly Volume 46.djvu/575

Rh perihelion of the comet of 1843—may be not substantial, but merely representative of a state of ether set in a particular undulating motion by the influence of the comet. The origin of comets may be various—from solar or planetary explosions; from explosions in distant stars, or from the scattered matter in space—any or all of these. Meteoric stones, meteoric showers, and cosmic dust are considered, and an equal variety of possible origins is supposed for them. The sidereal system comes next under review, in the several categories of the constellations, the positions of the stars in the sky, their magnitude or brightness, the measurement of celestial distances, the light of the stars, changes observed in the heavens, double, multiple, and colored stars, the proper motions of the stars, and the structure of the visible universe. A hopeless effort is made to convey a conception of the magnitude of the universe. We might sail forever through it with the velocity of light, and still be only at the beginning of our journey. The last chapter gives a simple lesson in home astronomy—a fitting introduction to Mr. Serviss's Astronomy with an Opera-Glass.

biography, the authors claim, has been prepared "under unique facilities for procuring fullness and accuracy of fact, and thence for creating a living and sympathetic picture of the man. The materials have been obtained from the observations of a close business and friendly association of the authors with their subject for a period of thirteen years, and from the verbal and written data which Mr. Edison has most freely and kindly supplied. To this should be added manuscripts from the leading members of the Edison staff and the inventor's private files of periodicals, covering over thirty years, and embracing the best work of American and transatlantic journalism." Having made careful and discriminating use of this material, the authors believe they have given the first full, accurate, and, to Edison, satisfactory life of the inventor. Besides the matter conventionally appropriate to a biography and the accounts of Edison's numerous and valuable inventions, the book abounds in anecdotes, lively sketches, dramatic passages, and little incidents illustrating the vicissitudes of the subject's career, his peculiar turns of mind, his skill in adaptation and manipulation of already existing mechanism to give effect to his new ideas, and the ever-consistent bent of his genius. The account of his work with the electric light is varied with the descriptions of the journeys of his agents in South America and Asia in search of the best fiber for lamps, occupying two chapters. There are given us here the stories and descriptions of Edison's many experiments and improvements in telegraphy, his vote-recorder, his phonograph and allied instruments, his work in electric railroading, the kinetoscope, and the other applications. The laboratories at Menlo Park and Orange, and the various shops, are noticed in such a way as to give a current view of the development of the electric industry from its modest and doubtful beginnings to its present triumphant prosperity. The tone of the biography is one of enthusiastic admiration, and the book is profusely illustrated.

book is written primarily with reference to children, especially in schools, who have a deficient sense of hearing, but whose teachers and even their parents may not be aware of the fact. "Yet the deafness may be serious enough to interfere with progress in their studies. Such children are frequently considered dull and inattentive pupils. Many suffer from catarrhal affections and thereby present a variability of hearing, which makes them appear to better advantage on some days than on others. Thus they add to the teachers difficulty in distinguishing them from the willfully disobedient. If one ear is defective and the other not, there will be times when the child hears well, and soon after, having turned his head, he fails to understand and becomes indifferent." The number of children troubled with defects in hearing has been found much larger in the schools of several different countries than any one at first thought would