THE PRINCIPLES OF By ALEXANDER MCADIE A. Lawrence Rotch Professor of Meteorology, Harvard University, and THE PREFACE Several excellent textbooks on meteorology have been published in this country, the latest having been issued about seven years ago. In the interval since then much new material in connection with the exploration of the upper air has accumulated, which has been published only in scientific journals; and it is thought advisable that an effort be made to present this new knowledge in a convenient form, even if considerably condensed. Again, the student of to-day is interested in aerography in much the same way that the student of geography is interested in his subject. He is not satisfied with merely locating places, a task essentially mechanical; but goes on to trace the relationship between physiography and the development of communities or nationstruly an educational labor. Thus aërography resembles geography in the larger sense, while meteorology, according to the general acceptation of the term, remains the science of recording diverse atmospheric conditions. The chief purpose of aerography is exploration with a view to utilizing the knowledge gained to insure human safety and to expedite progress. The present book, therefore, aims to give prominence to recent work that has been done in exploration of the air; such work as that of the first director of the Blue Hill Observatory, the late Professor A. Lawrence Rotch, and his colleague and friend, the late Teisserenc de Bort. Frequent reference is made to the work of Shaw, Dines, Gold, Cave, Hergesell, Assmann, Köppen, Sprung, Süring, Berson, and a host of other modern workers who, in many lands, and often under difficulty, have contributed to this slow conquest of the air. Another important reason for offering this volume is the desire to further the use of the c.g.s. system of units. Throughout the book preference is given to absolute units, in the hope that the student will forget as soon as possible the old, arbitrary, and irrational units. This, it seems to the author, is of importance for at least three reasons: first, the use of these units leads to clear-cut conceptions of the magnitude of the changes, regular or irregular, in pressure, temperature, humidity, and air flow; second, by means of them much time is saved in all computations; and third, they lessen the chance for error in observing and reducing. |