Repository: UIHistories Project: Board of Trustees Minutes - 1871 [PAGE 162]

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154 There is another phase of these greater northern and southern upper and lower general air currents, which is particularly interesting to us, as determining to a great extent the prevailing character of our winters, which may be called their general drift. Since the entire moving force of the great trade winds, or of those winds that move from the pole toward the equator, is in the south toward the sun, the return current is, so to speak, left to get out of the way, or to get back to the north, as best it can, with no specific northern force to attract it thither; it is simply rolled and pushed back by the constant accumulation and piling up of air at the equator, drawn there by the constant power of the sun and its heat. Of course this return current seeks the easiest way baek again to the poles which it can find, or elects the path of least resistance, and this will be, of course, over the warmest and dryest parts of the earth, as there the opposing northern current will have least weight and force,and the returning south current will meet therewith least resistance. Now, it naturally and almost invariably happens that the greater bulk of the flow from the north goes down south over one continent, while the greater volume of the return current goes up north over some other continent, in some other part of the world; or the one volume may go down south on one side of a continent or high mountain range, and return north on the other side of it. Of course, on the one side, the prevailing winter winds are north and it will be cold, while on the other side or continent their prevailing winds will be from the south return current, and they will have a mild, warm winter. So absolutely inevitable is this, that whenever we read, or hear, or know of an extremely cold winter over one wide reach of longitude, over which the northern winds are flowing southward, we know that we shall hear, and must hear of some parts of the earth or sea, over which this cold current returned again, made warm from the south, and bringing them a winter as genial and warm as that on the other side, or over the other parts, was cold and severe—inasmuch that a cold winter all over the globe, at one and the same time, is an utter impossibility. The present condition of warmth that has prevailed over this continent throughout the tall, as contrasted with the extreme cold reported from around Paris and in Europe, is only one very common illustration of this inevitable law. In countries where the wind-flow from the north predominates, they have now and then warm and hopeful days, with south winds ; but after every storm, the wind whisks again round into the northwest, and blows cold enough to take the hair from off a man's head. But where the opposite southern flow, or flow from the south prevails, although they have cold days, or cold weeks it may be, still the storms