Q. Why will there be little or no rain if the air be moist, and the barometer remains very low?
A. If the air be ever so moist, rain will never fall till cold air has been introduced to condense the vapour; and the moment that the cold air is introduced, the barometer will rise.
Q. What is the 5TH SPECIAL RULE in regard to the barometer?
A. In summer-time (after a long continuance of fair weather) the barometer will fall gradually for 2 or 3 days before rain comes; but if the fall of the mercury be very sudden, a thunder-storm is at hand.
Q. What is the 6TH SPECIAL RULE in regard to the barometer?
A. When the sky is cloudless, and seems to promise fair weather, if the barometer be low, the face of the sky will soon be suddenly overcast.
Q. What is the 7TH SPECIAL RULE in regard to the barometer?
A. Dark dense clouds will pass over without rain, when the barometer is high; but if the barometer be low, it will often rain without any gathering of clouds.
Q. What is the 8TH SPECIAL RULE in regard to the barometer?