PhG 510873 KE 31950 1876, Oct. 17. Minst Fund. HARVARD LONDON: JOHN KING AND CO., THE QUEEN STREET PRINTING WORKS, AND OLD JEWRY, E.C. PREFACE. THIS study of the nature, character, and effect of the prevailing winds of a country, and of the currents which wash its shores, is as much a part of its geography as is that of the outline of its coasts, or of the contour of its mountains. In its widest extent it not only brings us face to face with the ever fresh phenomena of Nature, and leads us to a closer acquaintance with the secrets of her power, but it sets forth much that is soundly and practically useful to the seaman. It has thus been fully recognised as a branch of Geographical Science not only by the Royal Geographical Society but by the Admiralty, although by a curious contradiction it has hitherto been assigned, almost exclusively, to Meteorology, or rather to that particular division of Meteorology which treats of the hydrostatic condition of the Atmosphere and the Ocean. Meteorology of course forms a very important part of all questions that relate to the movements of the air; the differences and variations in density, elastic force, temperature or humidity, must at all times exercise a very great influence on the relative equilibrium of atmospheric masses; but the difficulty which confessedly overlies the whole subject seems to me due, in part at least, to the positive way in which it has so generally been assumed that these hydrostatic fluctuations are the sole causes of atmospheric motion; due, in fact, to the want of a clear understanding of the distinction and connection between Meteorology and Geography. To illustrate this distinction and this connection, I have devoted a considerable portion of the following pages; but a still larger portion is devoted to a detailed and analytical account of the phenomena referred to, and to an attempt to trace them back to their natural causes, whether those causes are geographical, meteorological, or cosmical. In doing so, I have adopted a method which, though it differs essentially from that which has of late years been very generally followed, is, I would submit, both more exact and more scientific. I have endeavoured to explain the phenomena which are observed, rather than to observe phenomena in illustration of theoretical 'views. There is no more dangerous source of error in physical science than a strong conviction that certain phenomena must exist, and a determination to find them. Difficult as it is to banish from the mind all preconceived ideas, and to enquire into things as they really are, not. as they have been imagined to be, it is only by such a beginning that we can hope to arrive at a knowledge and understanding of the truth. But the fact is, we are at all times in too great a hurry to generalize; we are too fond of repeating that Newton worked out the great idea of universal gravitation by generalizing from the fall of an apple: perhaps he did; but we are not Newtons, and might occasionally do well to remember that even a donkey -according to Mr. Lowe-generalizes on the obnoxious nature of wheel-barrows. Generalization is necessary for scientific classification; it is necessary for a right understanding of the phenomena classified; it is necessary, if only as an aid to inemory; but a hasty generalization is, in all probability, a false one, and-founded on imperfect and incorrect data-leads to results on which no confidence whatever can be placed. The work which I have undertaken would evidently not be complete without generalization without generalization, it would have been impossible for me to attempt anything like a systematic explanation of my subject, or to enter into the important question of cause: but to that generalization I have been guided by thousands and thousands of independent and detailed observations, careless of any theory to which it and they might conduct me. Thus, entering on the subject from a different starting point, and travelling by a different road from that taken by my more immediate predecessors, the results of my enquiry are also, in many cases, very different. In the body of the work I have had to call frequent attention to the main points of this difference; for though I have endeavoured, as much as possible, to avoid what might be mistaken for controversial display, opinions, supported by the weight of many years general acceptance, and by the writings of many distinguished meteorologists, are not lightly to be set aside. But whether the conclusions I have formed are right or wrong, there cannot, I conceive, be any doubt as to the correctness of the method I have adopted. It is the method which has been adopted in every branch of science-except this-and often with the most astounding success: it is the method which has led to every advance in science during the last three hundred years, from the time of Kepler down to the present day. The method is not answerable for any mistakes I may have made: whoever or whatever is wrong, it is right. By analysis of facts and observations I have been led to my conclusions; on these facts, these observations, the whole work |