_All revolving bodies, left free as to direction, travel in a curve in a direction opposite to that of their rotation._ This curve is usually some form of conic section: an ellipse, parabola or hyperbola. The planets, and some comets, move in ellipses. Some comets travel parabolas or hyperbolas. And the parabola is the customary path of the cyclonic storm. As the cyclone in the northern hemisphere rotates from right to left, and in the southern from left to right, their paths must necessarily be in opposite directions, as may be seen by the accompanying diagram. So in either case, the direction of the path is always away from the equator. [Illustration] As far as the United States are concerned, most non-cyclonic storms originate in the Saskatchewan country, or along the southeastern slope of the Rocky Mountains. By far the greater number pass over the St. Lawrence valley. A small number are developed in the Gulf, or in the Pacific: but these are much affected, often broken up, in crossing the Rocky or Appalachian systems. The usual course is somewhat north of east; but there are a few notable exceptions. The immense amount of vapor wafted up the Mississippi valley induces some low area storms to move southward from Manitoba into the upper Mississippi valley. In like manner, the excessive moisture along our north Pacific coast causes occasional storms to move southward from Alaska to Oregon. But the course of a cyclonic storm, we have seen, must be different. The accompanying diagram illustrates the fact that the wind blows from all directions toward the center of the storm. As the storm revolves, the wind would come apparently from the south for any one on the eastern edge of the cyclone of the northern hemisphere. Hence, in the case of a storm of large diameter, people in Richmond or Washington may often be surprised by an apparent northeast gale, which reaches them before it strikes New York or Boston. At the center of the storm is absolute calm. So if a cyclone pass centrally over any point in the northern hemisphere, a person at that place will find the wind blowing violently from the southeast: then after an interval of calm, it will blow with equal violence from the northwest. This will be the case if the path of the storm has already turned to the northeast, so that its northeast quarter may be called its front. If on the northwest course, however, the apparently alternate winds would be from the northeast and southwest. So one in the path of a southern cyclone would find the winds proceeding from the same quarters; for though it revolves in the opposite direction, its front or path is also in the opposite direction; so in either hemisphere, the southeast or the northeast wind will be the first felt by one directly in the track of the storm. [Illustration: ROTATION OF STORMS.]