MESSRS. EDITORS:—That we have “trade winds” blowing from the northeast in the northern equinoctial belt, and from the southeast in the southern equinoctial belt, is a fact long known to mariners, and equally well known to all students of Nature. That these currents are piled up, rarified and made to rush toward the west by the compound force of the two streams and the calorifying power of the torrid zone, is all rational enough in itself; that is to say, the uprising and westward moving of the atmosphere of this equinoctial belt is a. necessary consequence te the inflowing condition of the trade winds. Now, where does this wind, i. e. atmosphere, come from ? *nd whither does it go? It has an inlet here, and it must have an outlet here, also. Maury says it goes to the poles K the southwest "passage winds " in the northern hemisphere, and the northwest passage winds in the southern hemisphere. These are facts also known to mariners. But how do they make their circuits back? Mariners cannot tell. They only feel their courses on the surface of the sea. -Maury deduces theoretically that they return by upper currents from the northwest in the northern hemisphere, and from the southeast in the southern half of the globe. I shall not, in this brief statement, follow Maury s theory for their return, profound though it may be, because the facts as elicited respecting the upper currents of the atmosphere 6how the return current in our latitude to come from the northwest. In my twenty-five years' balloon sailing, I have always found two currents of air. One from the southwest ; another higher up, from the northwest. Between these two currents, an eddy current is found moving toward the east. This northwest current is drawn into the equatorial vortex, where it becomes the northeast trade wind known to mariners. The reverse is the use in the southern hemisphere. Having thus far traced the actual courses of the wind, let us examine the eanse. Assuming that the equatorial heat and the polar cold are the causes of the currents going to and fro by incessant heating and cooling processes, operating upon the mobile atmosphere, shall we not find in the same cause, though in a modified form, the constant tendency of tlie atmosphere in one zone^moving from east to west; that is to say, will not the warming process of the coming morning sun, rising constantly m the cast, have a tendency to draw the atmosphere in that direction, bringing it from tho cooling shades of night, also constantly acting upon it on the western side of the daylight? That is the best theory that I can hang upon the fact. I do not pretend to say that it is the true theory, but the facts of the wind's courses are nevertheless established ; on the surface of the earth by mariners, and in the upper currents by twenty-five years' sailing among them. Upon this great circulatory system of the vast atmosphere I base the ultimate success of aerial navigation. By studying the currents and deflections in detail, we will be enabled to move among them to any part of the globe we wish to reach. Maury leaves nothing to be deduced in his outlines of the currents of air on tho surface of the globe ; they are all elaborated and sys-temized facts ; and these currents on the surface partake of various directions corresponding to the points of the compass. It is therefore a rational deduction that they must have their corresponding counter currents above, though my experience only positively reveals the two spoken of above ; one from the southwest, the other overlapping it and coming from the northwest. There is yet a new world of wonder and happiness in the vast and unexplored region of the atmosphere. Ought this grand subject not be brought under the scrutiny and general investigation of artistic and scientific men by a preliminary experiment of sailing round the globe with a balloon ? It can be done at a cost of not over $10,000. JOHN WISE. Lancaster, Pa., Dec. 4, 1860.