A Catechism of Familiar Things; Their History, and the Events Which Led to Their Discovery. With a Short Explanation of Some of the Principal Natural Phenomena. For the Use of Schools and Families. Enlarged and Revised Edition.

CHAPTER I.

DEW, WA­TER, RAIN, SNOW, HAIL, AT­MO­SPHERE, WIND, LIGHT­NING, THUN­DER, ELEC­TRIC­ITY, TWI­LIGHT, AND THE AU­RO­RA BO­RE­ALIS.

What is Dew?

Mois­ture col­lect­ed from the at­mo­sphere by the ac­tion of cold. Dur­ing the day, the pow­er­ful heat of the sun caus­es to arise from the earth and wa­ter a moist va­por, which, af­ter the sun sinks be­low the hori­zon, is con­densed by the cold, and falls in the form of dew. Dews are more co­pi­ous in the Spring and Au­tumn than at any oth­er sea­son; in warm coun­tries than in cold ones: be­cause of the sud­den changes of tem­per­ature. Egypt abounds in dews all the sum­mer; for the air be­ing too hot to con­dense the va­pors in the day-​time, they nev­er gath­er in­to clouds and form rain.

_Hori­zon_, the line which bounds the view on all sides, so that the earth and sky ap­pear to meet. A Greek word, from the verb sig­ni­fy­ing to mark bound­aries.

_Tem­per­ature_, de­gree of heat or cold.

_Con­dense_, to cause the par­ti­cles of a body to ap­proach or unite more close­ly.

What are its us­es?

It cools and re­fresh­es the veg­etable cre­ation, and pre­vents it from be­ing de­stroyed by the heat of the sun. All hot coun­tries where there is lit­tle or no rain are there­fore blessed with this pro­vi­sion by the all-​boun­ti­ful Cre­ator, to ren­der them lux­uri­ant and in­hab­it­able; and the dews which fall are so co­pi­ous, that the earth is as deeply soaked with them dur­ing the night as if a heavy rain had fall­en. For this rea­son al­so it is, that we so of­ten read in the Bible of the “dew of Heav­en” be­ing promised to the Is­raelites as a sig­nal fa­vor.

_Lux­uri­ant_, fer­tile, flour­ish­ing.

_Sig­nal_, re­mark­able, em­inent.

From what does the va­por orig­inate?

Va­por is wa­ter, com­bined with a still greater quan­ti­ty of caloric,--that is, an im­pon­der­able and sub­tile form of mat­ter, which caus­es the sen­sa­tion of heat; and which, driv­ing asun­der the par­ti­cles of the wa­ter, ren­ders it aer­iform.

_Im­pon­der­able_, with­out sen­si­ble weight.

_Sub­tile_, thin, not dense, or com­pact.

_Par­ti­cle_, a small por­tion of mat­ter.

_Aer­iform_, hav­ing the form of air.

What is Wa­ter?

The flu­id which cov­ers more than three-​fifths of the sur­face of our globe, and which is nec­es­sary for the life and health of the an­imal and veg­etable cre­ation; for with­out wa­ter there would be nei­ther rain nor dew, and ev­ery­thing would per­ish. It is like­wise a nec­es­sary bev­er­age for man and the in­fe­ri­or an­imals.

_Bev­er­age_, drink, liquor for drink­ing.

In how many states do we find Wa­ter?

In four: 1st, sol­id, as in ice, snow, hail, &c.; 2d, flu­id, as in its com­mon form; 3d, aer­iform, as in steam; and 4th, in a state of union with oth­er mat­ter. Its most sim­ple state is that of ice, which is wa­ter de­prived of a cer­tain por­tion of its caloric: crys­tal­liza­tion then takes place, and the wa­ter be­comes sol­id and is called ice.

_Crys­tal­liza­tion_, the pro­cess by which the parts of a sol­id body, sep­arat­ed by so­lu­tion or fu­sion, are again brought in­to the sol­id form. If the pro­cess is slow, the fig­ure as­sumed is reg­ular and bound­ed by plane and smooth sur­faces.

_So­lu­tion_, the dif­fu­sion of a sol­id through some liq­uid.

_Fu­sion_, melt­ing, or ren­der­ing flu­id by heat.

From what cause is the Wa­ter de­prived of its caloric?

From the cold­ness of the at­mo­sphere: un­der­neath the poles of our globe it is most­ly sol­id; there it is sim­ilar to the hard­est rocks, and may be cut with a chis­el, like stone or mar­ble. This great so­lid­ity is oc­ca­sioned by the low tem­per­ature of the sur­round­ing air; and in very cold coun­tries ice may be ground so fine as to be blown away by the wind, and will still be ice.

_Poles_, the ex­trem­ities or ends of the ax­is, an imag­inary line, sup­posed to be drawn through the cen­tre of the earth; or when ap­plied to the heav­ens, the two points di­rect­ly over them.

Is ice the on­ly in­stance of Wa­ter ex­ist­ing in a state of so­lid­ity?

No; it is found in a sol­id state in many min­er­als, as in mar­ble, &c., and is then called _wa­ter of Crys­tal­liza­tion_. It is es­sen­tial, in many cas­es, to their so­lid­ity and trans­paren­cy.

_Es­sen­tial_, nec­es­sary.

_Trans­paren­cy_, clear­ness, the pow­er of trans­mit­ting light.

Does Na­ture de­com­pose Wa­ter in any of her op­er­ations?

Yes: ev­ery liv­ing veg­etable has the pow­er of de­com­pos­ing wa­ter, by a se­cret pro­cess pe­cu­liar to it­self. Fish, too, and all cold-​blood­ed am­phibi­ous an­imals are gift­ed with the same pow­er.

_De­com­pos­ing_, sep­arat­ing a mixed body in­to its sev­er­al parts.

_Am­phibi­ous_, able to live both in wa­ter and out of it.

Of what use is this pow­er to veg­eta­bles?

The wa­ter which they de­com­pose af­fords them nour­ish­ment for the sup­port of their vi­tal juices, and en­ables them, by com­bin­ing the flu­id gas­es which com­pose it with those of the air and the soil, to form their dif­fer­ent prod­ucts; while the su­per­flu­ous gas is abun­dant­ly giv­en out by their leaves, to re­fresh the spent air, and ren­der it whole­some for the an­imals that breathe it.

_Vi­tal_, be­long­ing to life, nec­es­sary to ex­is­tence.

_Su­per­flu­ous_, un­nec­es­sary, not want­ed.

What is Rain?

The con­densed aque­ous va­pors raised in the at­mo­sphere by the sun and wind, con­vert­ed in­to clouds, which fall in rain, snow, hail, or mist: their falling is oc­ca­sioned by their own weight in a col­li­sion pro­duced by con­trary cur­rents of wind, from the clouds pass­ing in­to a cold­er part of the air, or by elec­tric­ity. If the va­pors are more co­pi­ous, and rise a lit­tle high­er, they form a mist or fog, which is vis­ible to the eye; high­er still they pro­duce rain. Hence we may ac­count for the changes of the weath­er: why a cold sum­mer is al­ways a wet one--a warm, a dry one.

_Aque­ous_, wa­tery; con­sist­ing of wa­ter.

_Col­li­sion_, a strik­ing to­geth­er, a clash, a meet­ing.

_Elec­tric­ity_, a nat­ural agent ex­ist­ing in all bod­ies (see page 18).

What sea­sons are more li­able to rain than oth­ers?

The Spring and Au­tumn are gen­er­al­ly the most rainy sea­sons, the va­pors _rise_ more plen­ti­ful­ly in Spring; and in the Au­tumn, as the sun re­cedes from us and the cold in­creas­es, the va­pors, which lin­gered above us dur­ing the sum­mer heats, _fall_ more eas­ily.

_Re­cede_, to fall back, to re­treat.

What is Snow?

Rain con­gealed by cold in the at­mo­sphere, which caus­es it to fall to the earth in white flakes. Snow fer­til­izes the ground by de­fend­ing the roots of plants from the in­tenser cold of the air and the pierc­ing winds.

_Con­gealed_, turned by the force of cold from a flu­id to a sol­id state; hard­ened.

_Fer­til­ize_, to ren­der fruit­ful.

_In­tenser_, raised to a high­er de­gree, more pow­er­ful.

What is Hail?

Drops of rain frozen in their pas­sage through cold air. Hail as­sumes var­ious fig­ures ac­cord­ing to the de­grees of heat or cold through which it pass­es, be­ing some­times round, flat, &c.

What is the At­mo­sphere?

The mass of aer­iform flu­id which en­com­pass­es the earth on all sides: it ex­tends about fifty miles above its sur­face. Air is the elas­tic flu­id of which it is com­posed.

_Elas­tic_, hav­ing the pow­er of spring­ing back, or re­cov­er­ing its for­mer fig­ure af­ter the re­moval of any ex­ter­nal pres­sure which has al­tered that fig­ure. When the force which com­press­es the air is re­moved, it ex­pands and re­sumes its for­mer state.

What are the us­es of air?

It is nec­es­sary to the well-​be­ing of man, since with­out it nei­ther he nor any an­imal or veg­etable could ex­ist. If it were not for at­mo­spher­ic air, we should be un­able to con­verse with each oth­er; we should know noth­ing of sound or smell; or of the plea­sures which arise from the var­ie­gat­ed prospects which sur­round us: it is to the pres­ence of air and car­bon­ic acid that wa­ter owes its agree­able taste. Boil­ing de­prives it of the greater part of these, and ren­ders it in­sipid.

_Var­ie­gat­ed_, di­ver­si­fied, changed; adorned with dif­fer­ent col­ors.

_In­sipid_, taste­less.

What is Wind?

Air in mo­tion with any de­gree of ve­loc­ity.

What is Light­ning?

The ef­fect of elec­tric­ity in the clouds. A flash of light­ning is sim­ply a stream of the elec­tric flu­id pass­ing from the clouds to the earth, from the earth to the clouds, or from one cloud to an­oth­er. Light­ning usu­al­ly strikes the high­est and most point­ed ob­jects, as high hills, trees, spires, masts of ships, &c.

What is Thun­der?

The re­port which ac­com­pa­nies the elec­tri­cal union of the clouds: or the echoes of the re­port be­tween them and the earth. Thun­der is caused by a sud­den dis­charge of elec­tri­cal mat­ter col­lect­ed in the air, by which vi­bra­tions are pro­duced, which give rise to the sound.

What is Elec­tric­ity?

One of those agents pass­ing through the earth and all sub­stances, with­out giv­ing any out­ward signs of its pres­ence, when at rest; yet when ac­tive, of­ten pro­duc­ing vi­olent and de­struc­tive ef­fects. It is _sup­posed_ to be a high­ly elas­tic flu­id, ca­pa­ble of mov­ing through mat­ter. Clouds owe their form and ex­is­tence, prob­ably, to it; and it pass­es through all sub­stances, but more eas­ily through met­als, wa­ter, the hu­man body, &c., which are called con­duc­tors, than through air, glass, and silk, which are called _non_-con­duc­tors. When bod­ies are not sur­round­ed with non-​con­duc­tors, the elec­tric­ity es­capes quick­ly in­to the earth.

To what part of bod­ies is Elec­tric­ity con­fined?

To their sur­faces, as the out­side may be elec­tric, and the in­side in a state of neu­tral­ity. The heat pro­duced by an elec­tric shock is very pow­er­ful, but is on­ly ac­com­pa­nied by light when the flu­id is ob­struct­ed in its pas­sage. The pro­duc­tion and con­den­sa­tion of va­por is a great source of the at­mo­spher­ic elec­tric­ity.

_Con­den­sa­tion_, the act of mak­ing any body dense or com­pact; that is, of bring­ing its parts in­to clos­er union.

In what oth­er sense is the term Elec­tric­ity em­ployed?

This term is al­so em­ployed to des­ig­nate that im­por­tant branch of knowl­edge which re­lates to the prop­er­ties shown by cer­tain bod­ies when rubbed against, or oth­er­wise brought in con­tact with, each oth­er, to at­tract sub­stances, and emit sparks of fire.

_Des­ig­nate_, to point out by some par­tic­ular to­ken.

_Emit_, to send forth, to throw out.

[Il­lus­tra­tion: CUT­TING AND GATH­ER­ING ICE, ON THE HUD­SON RIV­ER, NEW YORK.]

Whence is the word de­rived?

From _elec­tron_, the Greek word for am­ber, a yel­low trans­par­ent sub­stance, re­mark­able for its elec­tri­cal pow­er when rubbed: am­ber is of a resinous na­ture, and is col­lect­ed from the sea-​shore, or dug from the earth, in many parts of the world. It is em­ployed in the man­ufac­ture of beads and oth­er toys, on ac­count of its trans­paren­cy; is of some use in medicine, and in the mak­ing of var­nish­es.

_Trans­par­ent_, clear, ca­pa­ble of be­ing seen through.

_Resinous_, con­tain­ing resin, a gum­my veg­etable juice.

Name a few sub­stances pos­sess­ing this re­mark­able prop­er­ty.

Silks of all kinds; the hair and fur of an­imals, pa­per, sul­phur, and some oth­er min­er­als; most of the pre­cious stones; the paste of which false gems are made; and many oth­er sub­stances used by us in the com­mon af­fairs of life, are sus­cep­ti­ble of elec­tri­cal ex­cite­ment; among do­mes­tic an­imals the cat fur­nish­es a re­mark­able in­stance. When dry and warm, the back of al­most any full-​grown cat (the dark­er its col­or the bet­ter) can be ex­cit­ed by rub­bing it with the hand in the di­rec­tion of the hair, a pro­cess which is ac­com­pa­nied with a slight snap­ping noise, and in the dark by flash­es of pale blue light. When a piece of glass is rubbed with silk, or a stick of red seal­ing-​wax with woollen cloth, each sub­stance ac­quires the prop­er­ty of at­tract­ing and re­pelling feath­ers, straws, threads of cot­ton, and oth­er light sub­stances; the sub­stances just men­tioned as high­ly elec­tric are, how­ev­er, mere­ly spec­imens. All ob­jects, with­out ex­cep­tion, most prob­ably are ca­pa­ble of be­ing elec­tri­cal­ly ex­cit­ed; but some re­quire more com­pli­cat­ed con­trivances to pro­duce it than oth­ers.

_Elec­tric_, hav­ing the prop­er­ties of elec­tric­ity.

_Sus­cep­ti­ble_, dis­posed to ad­mit eas­ily.

_Re­pelling_, the act of driv­ing back.

_Com­pli­cat­ed_, formed by the union of sev­er­al parts in one.

Is there not a ma­chine by which we are en­abled to ob­tain large sup­plies of elec­tric pow­er at plea­sure?

Yes; the elec­tri­cal ma­chine. It is made of dif­fer­ent forms and sizes: for com­mon pur­pos­es those of the sim­plest form are the best. A com­mon form of the ma­chine con­sists of a cir­cu­lar plate of glass, which can be turned about a hor­izon­tal ax­is by means of a suit­able han­dle. This plate turns be­tween two sup­ports, and near its up­per and low­er edges are two pairs of cush­ions, usu­al­ly made of leather, stuffed with horse-​hair and coat­ed with a mix­ture of zinc, tin, and mer­cury, called an _amal­gam_. These cush­ions are the rub­bers for pro­duc­ing fric­tion, and are con­nect­ed with the earth by means of a met­al chain or rod. Two large hol­low cylin­ders of brass with glob­ular ends, each sup­port­ed by two glass pil­lars, con­sti­tute the reser­voir for re­ceiv­ing the elec­tric­ity. They are called the _prime con­duc­tors_, and are sup­plied with U-​shaped rods of met­al, fur­nished with points along their sides, called _combs_, for the pur­pose of re­ceiv­ing the elec­tric­ity from the glass plate, the arms of the U be­ing held up­on ei­ther side. The oth­er ends of the con­duc­tors are con­nect­ed by a rod from the mid­dle of which projects an­oth­er rod ter­mi­nat­ing in a knob, for de­liv­er­ing the spark.

On turn­ing the plate, a faint snap­ping sound is heard, and when the room is dark­ened, a spark is seen to be thrown out from the knob pro­ject­ing from the _prime con­duc­tors_.

Many cu­ri­ous and in­ter­est­ing ex­per­iments may be per­formed by means of the ma­chine, il­lus­trat­ing the gen­er­al prop­er­ties of elec­tric­ity. For in­stance: a per­son stand­ing on an in­su­lat­ed bench, that is, a bench with glass legs, or hav­ing the legs rest­ing on glass, and hav­ing one hand on the con­duc­tor, can send sparks, with the oth­er hand, to ev­ery­thing and ev­ery­body about. This il­lus­trates com­mu­ni­ca­tion of elec­tric­ity by con­tact. A wood­en head, cov­ered with long hairs, when placed on the con­duc­tor, il­lus­trates elec­tri­cal re­pul­sion, by the hairs stand­ing on end.

If the hand is held to the knob, sparks will pass from it in rapid suc­ces­sion, caus­ing in the hand a sen­sa­tion of pain. This is called an _elec­tric shock_, and is caused by the elec­tric flu­id oc­ca­sion­ing a sud­den mo­tion by the con­trac­tion of the mus­cles through which it pass­es. The force of the shock is in pro­por­tion to the pow­er of the ma­chine.

What are the Mus­cles?

Bun­dles of thin fleshy fi­bres, or threads, fas­tened to the bones of an­imals, the con­trac­tion and ex­pan­sion of which move the bones or per­form the or­gan­ic func­tions of life.

_Or­gan­ic_, re­lat­ing to or­gans or nat­ural in­stru­ments by which some pro­cess is car­ried on.

_Func­tions_, em­ploy­ments or of­fices of any part of the body.

_Con­trac­tion_, draw­ing in or short­en­ing.

_Ex­pan­sion_, ex­tend­ing or spread­ing out.

What is Twi­light?

The light from the first dawn­ing of day to the ris­ing of the sun; and again be­tween its set­ting and the last re­mains of day. With­out twi­light, the sun's light would ap­pear at its ris­ing, and dis­ap­pear at its set­ting, in­stan­ta­neous­ly; and we should ex­pe­ri­ence a sud­den tran­si­tion from the bright­est sun­shine to the pro­found­est ob­scu­ri­ty. The du­ra­tion of twi­light is dif­fer­ent in dif­fer­ent cli­mates; and in the same places it varies at dif­fer­ent pe­ri­ods of the year.

_In­stan­ta­neous­ly_, done in an in­stant, in a mo­ment's time.

_Ob­scu­ri­ty_, dark­ness, want of light.

How is it pro­duced?

By the sun's re­frac­tion--that is, the vari­ation of the rays of light from their di­rect course, oc­ca­sioned by the dif­fer­ence of den­si­ty in the at­mo­sphere.

_Vari­ation_, change.

_Den­si­ty_, close­ness of parts, com­pact­ness.

What is the po­et­ical name for the morn­ing Twi­light?

Au­ro­ra, the god­dess of the morn­ing, and harbinger of the ris­ing sun: whom po­ets and artists rep­re­sent as drawn by white hors­es in a rose-​col­ored char­iot, un­fold­ing with her rosy fin­gers the por­tals of the East, pour­ing re­viv­ing dew up­on the earth, and re-​an­imat­ing plants and flow­ers.

_Harbinger_, a fore­run­ner.

_Por­tals_, gates, doors of en­trance.

_Re­an­imat­ing_, in­vig­orat­ing with new life.

What re­mark­able phe­nomenon is af­ford­ed to the in­hab­itants of the po­lar re­gions?

The Au­ro­ra Bo­re­alis, or North­ern Lights, a lu­mi­nous ap­pear­ance in the north­ern parts of the heav­ens, seen most­ly dur­ing win­ter, or in frosty weath­er, and clear evenings; it as­sumes a va­ri­ety of forms and hues, es­pe­cial­ly in the po­lar re­gions, where it ap­pears in its per­fec­tion, and proves a great so­lace to the in­hab­itants amidst the gloom of their long win­ter's night, which lasts from one to six months, while the sum­mer's day which suc­ceeds it lasts in like man­ner for the same pe­ri­od of time.

Of what na­ture is the Au­ro­ra Bo­re­alis?

It is de­cid­ed­ly an elec­tri­cal phe­nomenon which takes place in the high­er re­gions of the at­mo­sphere. It is some­how con­nect­ed with the mag­net­ic poles of the earth; and gen­er­al­ly ap­pears in form of a lu­mi­nous arch, from east to west, but nev­er from north to south.

_Phe­nomenon_, an ex­traor­di­nary ap­pear­ance. The word is from a Greek one, sig­ni­fy­ing, to show or ap­pear.

_Mag­net­ic_, be­long­ing to the mag­net, or load­stone.

_Lu­mi­nous_, bright, shin­ing.

In what coun­try is it seen con­stant­ly from Oc­to­ber to Christ­mas?

In Siberia, where it is re­mark­ably bright. On the west­ern coast of Hud­son's Bay, the sun no soon­er dis­ap­pears, than the Au­ro­ra Bo­re­alis dif­fus­es a thou­sand dif­fer­ent lights and col­ors with such daz­zling beau­ty, that even the full moon can­not eclipse it.