Q. Why is it often painful, and difficult to breathe, on a mountain top?
A. Because the pressure of air on the mountain top is not so great as on the plain; and the air inside our bodies (seeking to become of the same rarity) bursts through the pores of the body, and produces great pain.
Q. Why do we feel oppressed just previous to a storm?
A. Because the air is greatly rarefied by heat and vapour; and the air inside us (seeking to become of the same rarity) produces an oppressive and suffocating feeling.
Q. Why do divers suffer great pain in their eyes and ears under water?
A. Because the air at the bottom of the sea is more dense than the air on the surface; and while the air inside the diver’s body is settling into the same density, he feels oppressed with pain, especially in the ears.
Q. Why is this pain felt especially about the ears of a diver?
A. The ear is fitted with a small membrane called the drum (or tympanum), through which the dense air bursts, and the rupture very often produces incurable deafness.
Q. Why do our corns ache just previous to rain?
A. Previous to rain, the density of air is greatly lowered (as every one knows from the fall of the barometer); in consequence of an unequal pressure, our feet swell; but the hard corn, not being elastic, is painfully stretched and pressed.