When in Boston about fifteen years ago, I went to Blue Hill to witness the remarkable kite flying which was taking place at that time. The kites experimented with were of the Hargrave type, and of enormous dimensions. A steel wire and windlass worked by a steam engine was employed. I was told that on certain occasions the kites mounted extremely high, much higher than they were able to account for; but on this particular occasion, although they let out a great amount of wire, the kite did not mount very high. I have heard much discussion first and last regarding the flight of kites, and I think it is generally admitted that they do sometimes rise upwards and continue moving to the windward until they pass directly over the spot where they are attached to the earth. It was not, however, till about three years ago that I witnessed this phenomenon myself. Mr. Cody, who is the inventor of a very good kite, had been flying kites at the Crystal Palace for some months, and on one occasion I saw his kite rise, pass to the windward and directly over our heads. I took hold of the cord with both hands, and was somewhat surprised to find what the lifting effect was. The kite was, however, of large dimensions, but by no means so large as Mr. Cody’s “man-lifting kites.” In the drawing (Fig. 8) I have shown, at _a_, the action of a kite in a horizontal wind, lines _e_, _e_, showing the direction of the wind. A good kite will easily mount 45°, the angle shown, but on the occasion just mentioned, the sun had been shining brightly into the valley where the experiments took place, and an upward current of air had been determined. The cooler air was, of course, rushing in from each side and mounting in about the centre of the valley, and Mr. Cody’s kite, instead of flying in a horizontal wind, soon reached a point where the wind was ascending at an angle, as shown at _f_, _f_. The kite would therefore mount until at _b_, where it presented the same angle to the wind as with the horizontal wind at _a_, and if it should be made to fly at a higher angle, it might pass over to the position shown at _c_. But it must not be imagined that this phenomenon can be witnessed every day in the year. It is only on rare occasions that one is fortunate enough to find a wind which is blowing at a sufficiently sharp upward trend to cause a kite to pass to the windward over the point of support. Neither must it be supposed that this favourable condition of things is of long duration. As the centre of the upward current is constantly moving, it is certain that very soon it will move away from the point from which the kite is being flown. What is true of kites is also true of flying machines. It is very difficult indeed to make a kite mount providing that it is in a descending current of air, and one is just as likely to find a descending current as any other. Flying machines will, therefore, have to be made with a considerable amount of reserve energy, so as to be