A Guide To The Scientific Knowledge Of Things Familiar - novelonlinefull.com
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Q. _Why is it DANGEROUS to be NEAR a TREE, or lofty building, during a thunder-storm?_
A. Because a tall pointed object, (like a tree or spire,) will frequently _discharge_ a lightning-cloud; and then the electric fluid _will pa.s.s down it_, in its way to the earth.
Q. _How can a TREE or SPIRE DISCHARGE a lightning-cloud?_
A. A lightning-cloud (floating over a _plain_) may be _too far off_ to be discharged by it; but as a tree, or spire, would _shorten_ the distance between the cloud and its conductor, it might no longer be too far off a conductor to be discharged.
Q. _Is not air a CONDUCTOR of lightning?_
A. No; dry air is _not_ a conductor of lightning; and therefore, the flash _rends it in twain_, to get to some conductor.
Q. _Why would it be dangerous to stand near a tree or spire, while lightning is pa.s.sing down it?_
A. Because the electric fluid (called lightning) always rushes down the _outside_ of the tree or spire; and if any one were standing near, might pa.s.s through _him_, and kill or maim him.
Q. _Does lightning go through the inside or outside of a tree?_
A. It rolls down the _outside_ of a _tree_; but pa.s.ses through the _inside_ of a _man_.
Q. _Why does lightning pa.s.s down the OUTSIDE of a tree?_
A. Lightning always makes choice of the best conductors; and the _outside_ of a tree is a better conductor than the inside.
Q. _Why does lightning pa.s.s through the INSIDE of a man?_
A. As the _fluids_ of the human body make a better conductor than the _skin_, therefore lightning pa.s.ses _through_ a man, and not down the skin.
Q. _Why is it DANGEROUS to be near a deep RIVER, or any other running water, during a thunder-storm?_
A. Because running water is a good conductor; and lightning always takes in its course the _best conductors_.
Q. _Why is it dangerous for a man to be near water, in a thunder-storm?_
A. Because the _height of a man_ may be sufficient to discharge a cloud: and (if there were no _taller_ object nigh) the lightning might make the _man_ its conductor to the water.
Q. _Why is it DANGEROUS to RING CHURCH-BELLS during a thunder-storm?_
A. For two reasons: 1st--Because the steeple may _discharge_ the lightning-cloud, in consequence of its mere _height_.
2ndly--The swinging of the bells causes _a current of air_, which collects electric fluid.
Q. _Why is it unsafe to RUN or DRIVE FAST during a thunder-storm?_
A. The rapid motion of running causes a _current of air_, which collects electric fluid, and is often fatal.
Q. _What PARTS of a DWELLING are most DANGEROUS during a thunder-storm?_
A. The fire-place, (especially if the fire be _lighted_); the attics and cellar. It is also dangerous to sit close by the walls; to ring the bell; or to bar the shutters, during a thunder-storm.
Q. _Why is it DANGEROUS to sit BEFORE a FIRE, during a thunder-storm?_
A. Because the heated air and soot are conductors of lightning; especially when connected with such excellent conductors as the stove, fender, and fire-irons.
Q. _Why are the ATTICS and CELLAR DANGEROUS, during a thunder-storm?_
A. Lightning sometimes pa.s.ses _from the clouds_ to the earth, and sometimes _from the earth_ to the clouds; and therefore, the _middle story_ of a house is always the safest to be in, during a thunder-storm.
Q. _When does lightning pa.s.s FROM THE EARTH to the CLOUDS?_
A. When the clouds are in a "negative" state of electricity.
Q. _When does lightning pa.s.s FROM THE CLOUDS to the EARTH?_
A. When the clouds are in a "positive" state of electricity.
Q. _What is meant by the clouds being in a "positive state of electricity?"_
A. When the clouds contain _more_ electric fluid than they _generally_ do, they are said to be in a _positive_ state of electricity.
Q. _What is meant by the clouds being in a "negative state of electricity?"_
A. When the clouds contain _less_ electric fluid than they _ought_ to do, they are said to be in a _negative_ state of electricity.
Q. _Does the flash proceed from a negative or positive body?_
A. Always from a _positive_ body, or one over-burdened with electric fluid.
Q. _When lightning flashes from the earth to the clouds, what is the flash called?_
A. It is called the "returning stroke;" because the earth (being over-burdened with electric fluid) _returns_ the surplus quant.i.ty to the clouds.
