Fig. 6 gives the change in wind velocity at the different levels. There was an increase of wind at all the levels from the time of the passage of the anti-cyclone to the passage of the cyclone. The minimum of wind at 200 metres was in the anti-cyclone, with a secondary minimum during the passage of the centre of the cyclone. Figs. 7 to 10 show the changes in height from day to day of the equal conditions at the different levels. Fig. 7 shows the change in level of the isobars, which, although very small, is largest at the lower levels. The light broken lines in Fig. 7 and subsequent figures indicate the axes of the anti-cyclone and cyclone. That the axis of the cyclone was inclined backward, and that the high pressure occurred later at high than at low levels, was confirmed by the wind observations on the twenty-first. Fig. 8 shows the heights at which the same temperatures were found on successive days. Since the isotherms rose until the twenty-third, the temperature of the air up to 3000 metres was higher on the day of the cyclone than on the day of the anti-cyclone. Previous high flights indicate that this is the normal condition in the moving cyclones and anti-cyclones of the eastern United States. As the light broken lines represent the axes of the anti-cyclone and cyclone up to 3000 metres, it is seen that at this level the temperature at the place of maximum pressure is probably higher than at the place of minimum pressure, although this is not true for a vertical column of air above the earth. Fig. 9 gives the positions of equal humidities on successive days, saturated and cloudy areas being indicated by crossed shading, and less humidity by single ruling. From the laws of thermo-dynamics the unshaded curves should represent descending currents, and the shaded portions ascending ones. In the first case, increased warmth and a lower relative humidity are produced in the descent to a lower altitude; in the last case, cooling, increasing relative humidity, and condensation are produced by expansion in the ascent to a higher altitude. Consequently, two regions of descending air are indicated, one in the centre of the anti-cyclone, the other in the centre of the cyclone.