In the two cases given, if the change of weather follows immediately the movement of the barometrical column, that change will last only a very short time.
4.

If the barometer rises with slowness and in a continuous manner for two or three days, or even more, it announces fine weather, even when the rain will not cease during those three days, and _vice versa;_ but if the barometer rises two days or more during the rain, then, the fine weather having come, if it commences to fall again, the fine weather will last a very short time, and _vice versa_.
5.

In the spring and in the autumn, a sudden fall of the barometer presages wind.

In the summer, if the weather is very warm, it announces a storm.

In winter, after a frost of some duration, a rapid falling of the barometrical column announces a change of wind, accompanied by a thaw and rain; but a rising which happens during a frost which has already lasted a certain time, prognosticates snow.
6.