Part 46 (2/2)
Q. _Will polished METAL, smooth STONES, and woollen CLOTH, readily collect DEW?_
A. No. While gra.s.s 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 gra.s.s 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 pa.s.ses over them.
Q. _Why is a GRAVEL WALK almost DRY, when a gra.s.s plat is covered thick with DEW?_
A. _Gra.s.s_, (_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 GRa.s.s is SATURATED with DEW, and the GRAVEL is NOT?_
A. Yes. When the vapour of warm air comes in contact with the _cold gra.s.s_, it is instantly chilled into dew; but (as the gravel is _not so cold as the gra.s.s_) the vapour of air is _not so freely condensed_ as it pa.s.ses over the gravel.
Q. _Why does DEW rarely fall upon hard ROCKS and BARREN lands?_
A. Rocks and barren lands are so _compact_ and _hard_, that they can neither _absorb nor radiate much heat_; and (as their _temperature varies but very little_) very little _dew_ distils upon them.
Q. _Why does DEW fall more abundantly on CULTIVATED soils, than on BARREN lands?_
A. Because cultivated soils (being _loose and porous_) _absorb_ heat freely during the day, and _radiate it_ by night; and (being _much cooled by the rapid radiation of heat_) as the vapour of the air pa.s.ses over them, it is plentifully _condensed into dew_.
Q. _Shew the WISDOM of G.o.d in this arrangement._
A. Every plant and inch of land which _needs the moisture of dew_, is adapted to _collect it_; but _not a single drop even of dew is wasted_, where its refres.h.i.+ng moisture is _not required_.
Q. _Shew the WISDOM of G.o.d in making polished METAL and woollen CLOTH BAD RADIATORS of heat._
A. If polished metal collected dew as easily as gra.s.s, it could _never be kept dry_, and _free from rust_. Again, if woollen garments collected dew as readily as the leaves of trees, we should be _often soaking wet_, and subject to _constant colds_.
Q. _Shew how this affords a beautiful ill.u.s.tration of GIDEON'S MIRACLE, recorded in the book of Judges, VI. 37, 38._
A. The _fleece of wool_ (which is a _very bad radiator_ of heat) was _soaking wet_ with dew: when the _gra.s.s_ (which is a most _excellent radiator_) was _quite dry_.
Q. _Was not this CONTRARY to the laws of NATURE?_
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