Q. Why do persons who ascend in balloons feel pain in their eyes, ears and chest?
A. Because the air in the upper regions is more rare than the air in their bodies; and (till the equilibrium is restored) great pain is felt in all the more sensitive parts of the body.
Q. Why do persons who descend in diving-bells feel pain in their eyes, ears and chest?
A. Because the air in the sea is more dense than the air in their bodies; and (till the equilibrium is restored) great pain is felt in all the more sensitive parts of the body.
Q. Why does the sea heave and sigh just previous to a storm?
A. The density of the air (just previous to a storm) is very suddenly diminished, but the air in the sea is not so quickly affected; therefore the sea heaves and sighs in its effort to restore an equilibrium.
Q. Why is the air so universally still just previous to a tempest?
A. Because the air is suddenly and very greatly rarefied; and (as the density of the air is diminished) its power to transmit sound is diminished also.
Q. How do you know that rarefied air cannot transmit sound so well as dense air?