Q. Why will dew-drops roll over roses, &c. without wetting their petals?
A. The leaves of a rose contain an essential oil, which prevents them from absorbing the dew immediately.
Q. Why can a swan or duck dive under water without being wetted?
A. Because their feathers are covered with an oily secretion, which repels the water.
Q. What is the cause of mist?
A. When currents of air from land mix with currents of air from water, the currents from the water are condensed into mist by the colder currents blowing from the land.
Q. Why are the currents of air from the land colder than those blowing over water?
A. Because the earth radiates heat very freely, and (being greatly cooled down) cools the air also which comes in contact with it.
Q. Why is not the air, which passes over water, so cool as that which passes over land?