A. Because the walls are much thicker; and (if the frost has penetrated far into the bricks) it takes a long time to reduce them to the same temperature as the air.
Q. Why are banisters, &c. damp after a thaw?
A. The wooden banister (being made of some very close-grained, varnished wood) cannot change its temperature so fast as the air; and, therefore, remains cold some time after the thaw has set in.
Q. How does this account for the banisters being damp?
A. The vapour of the warm air (coming in contact with the cold banister) is chilled, and condensed into water upon it.
Q. Why is our breath visible in winter and not in summer?
A. In winter the coldness of the air condenses our breath into visible vapour; but in summer the air is not cold enough to condense it into visible vapour.
Q. Why are our hair and the brim of our hat often covered with little drops of pearly dew in winter-time?
A. The breath (issuing from our mouth and nose) is condensed into drops, as it comes in contact with our cold hair or hat; and (being condensed) hangs there in little dew-drops.