Q. Shew the wisdom of God in making grass, the leaves of trees, and all vegetables, excellent radiators of heat.
A. As vegetables require much moisture, and would often perish without a plentiful deposit of dew, God wisely made them to radiate heat freely, so as to chill the vapour (which touches them) into dew.
Q. Will polished metal, smooth stones, and woollen cloth, readily collect dew?
A. No. While grass and the leaves of plants are completely drenched with dew, a piece of polished metal, or of woollen cloth (lying on the same spot) will be almost dry.
Q. Why would polished metal and woollen cloth be dry, while grass and leaves are drenched with dew?
A. Because the polished metal and woollen cloth part with their heat so slowly, that the vapour of the air is not chilled into dew as it passes over them.
Q. Why is a gravel walk almost dry, when a grass plat is covered thick with dew?
A. Grass, (being a good radiator) throws off its heat very freely; but gravel (being a very bad radiator) parts with its heat very reluctantly.
Q. Is that the reason why grass is saturated with dew, and the gravel is not?
A. Yes. When the vapour of warm air comes in contact with the cold grass, it is instantly chilled into dew; but (as the gravel is not so cold as the grass) the vapour of air is not so freely condensed as it passes over the gravel.