Fig. 10 shows the change in height of the lines of equal wind velocity. With ascending currents and precipitation, high wind velocities were found at low levels, because of increased barometric gradient, while with the descending currents in the anti-cyclone and centre of the cyclone, the high velocities were found only at great altitudes. The study of these data indicate that the cyclonic and anti-cyclonic circulations observed in this latitude do not embrace any air-movements at greater altitudes than 2000 metres, except in front of the cyclone, when the air appears to be carried upward to a great height. Above 2000 metres there are probably other weak cyclones and anti-cyclones, or secondary ones, with their centres at different places from those at the earth's surface and producing a different circulation of wind. The observations of the cirrus clouds at Blue Hill indicate that at their level exists a cyclonic circulation above the anti-cyclone apparent at the earth's surface. The shallowness of our anti-cyclones would be inferred from the great differences in speed of the general atmospheric drift, for since the velocity of the general drift from the west is more than thirty times greater at 10,000 metres than it is at 200 metres, a circulation of great depth could not endure long. Cyclones and anti-cyclones appear to be but secondary phenomena in the great waves of warm and cold air which sweep across the United States from periodic causes. The origin of cyclones and anti-cyclones is perhaps the most important problem remaining for meteorological study. The theory that they are produced by differences of temperature in adjacent masses of air, or, as it is called, the convectional theory of the American meteorologists, Espy and Ferrel, is opposed by the observations on mountains in Europe which were collected by Dr. Hann of Vienna. If the question can be solved by the use of kites, as seems to be foreshadowed by the results just stated, another foundation-stone will be laid in the science of meteorology and the status of the kite established as an instrument of research. The kite fails when there is little or no wind at the ground, but it seems possible in such cases to lift the kite into the upper air, where there usually is wind, by attaching it to a small balloon that, after the kite can support itself, shall be detached automatically. While the height to which kites can rise is limited, and the limit is probably being approached, judging from the less gain of altitude in recent flights, yet it seems reasonable to expect that, with favourable conditions, a height of at least three miles will be reached.