IMAGE EVALUATION TEST TARGET (MT-3) 1.0 ^^ ta ■tt lii 122 Ufi 12.0 I.I u -^ Fhotographic ^Sciences COTporadon 33 WBT MAM STtKT Wnsni,N.Y. I4SM (ri6)t72-4S03 **> l^ ^ CIHM/ICMH Microfiche Series. CIHM/ICIVIH Collection de microfiches. Canadian Instituta for Historical Microraproductions / Institut Canadian da microraproductiona hiatoriquaa !»~ Technical and Bibliographic Notaa/Notas tachniquaa at bibliographiquaa Tha Inttituta haa attamptad to obtain tha bast original copy availabia for filming. Faaturas of thia copy which may Im bibiiographically uniqua. which may altar any of tha imagas in tha raproduction, or which may aignificantly changa tha usual mathod of filming, ara chackaid balow. □ Colourad covars/ Couvartura da coulaur r~1 Covars damagad/ D Couvartura andommagte Covars rastorad and/or laminatad/ Couvartura rastaur^ at/ou palliculAa r~l Covar titia missing/ La titra da couvartura manqua I — I Colourad maps/ Cartas gAographiquas m coulaur □ Colourad ink (i.a. othar than blua or black)/ Encra da coulaur (i.a. aufra qua blaua ou noira) D Colourad platas and/or illustrationa/ Planchas at/ou illuatrationa an coulaur □ Bound with othar material/ Relii avac d'autrea documents D D Tight binding may cauaa ahadowa or distortion along interior margin/ La failure serrie peut cauaar da I'ombra ou de la diatortion la long de la marge intirieure \ Blank leaves added during restoration may appear within the text. Whenever possible, these have been omitted from filming/ 11 se peut que certainea pages blanches aJoutAas lors d'une restauration apparaissent dans le texte. mais, lorsque cela Mait possible, ces pages n'ont pas *tt filmtes. Additional comments:/ Commentaires supplAmentaires; The( toth( L'Institut a microfilm^ la mailleur exemplaire qu'il lui a AtA possible de se procurer. Les details de cet exemplaire qui sont peut-Atre imiques du point de vue bibliographiqua, qui peuvent modifier una image reproduite, ou qui peuvent exiger une modification dans la mAthode normaia de filmaga sont indiqute ci-dassous. I I Coloured pagea/ Pagea da coulaur Pages damaged/ Pages endommag6as Pages restored and/oi Pages restaurtea at/ou pellicul6es Pages discoloured, stained or foxe< Pages dAcolortes, tachettes ou piquies Pages detached/ Pages ditach^es Showthrough/ Transparence Quality of prin Quality inAgala de I'impreaslon Includes supplementary materii Comprend du material aupplAmentaire Only edition available/ Seule Mition disponible I — I Pages damaged/ r~n Pages restored and/or laminated/ n~| Pages discoloured, stained or foxed/ I I Pages detached/ pr^ Showthrough/ r^ Quality of print varies/ r~l Includes supplementary material/ n~| Only edition available/ Thei poaal of th filmii Origi bagii thah aion. othei first I aion, or ill! The! shall TINU whic Mapi diffai entir bagii right raqui metl n Pages wholly or partially obscured by errata slips, tissues, etc.. have been ref limed to ensure the best possible image/ Les pagea totalament ou partiellement obscurcies par un fauillet d'errata. una palura. etc.. ont M filmAes A nouveau de fapon A obtanir la mailleure image possible. This item is filmed at the reduction ratio checked below/ Ce document est filmA au taux de reduction indiqu* ci'deasous. 10X 14X 18X 22X 26X 30X y 12X 16X aox a4x 28X 32X The copy filmad h«r« has b—n raproducad thanks to tha ganarosity of: ThoiiMs Fiihtr Rare Book Library, Univanity of Toronto Library L'axamplaira f ilmA f ut roproduit grAce k la gAnirositA da: Thomai Fithar Rara Book Library, Univanity of Toronto Library Tha imagas appaaring hara ara tha bast quality possibia considaring tha condition and lagibility of tha original copy and in kaaping with tha filming contract spacificatlons. Original copias in printad papar covars ara fllmad baginning with tha front covar and anding on tha last paga with a printad or iiiustratad Impras- sion, or tha back covar whan appropriata. Ail othar original copiaa ara filmad baginning on tha first paga with a printad or illuatratad impras- sion, and anding on tha last paga with a printad or Illuatratad imprassion. Tha last racordad frama on aach microflcha shall contain tha symbol —'^ (maaning "CON- TINUED"), or tha symbol V (maaning "END"), whichavar applias. Las imagas suivantes ont AtA reproduites avec le plus grand sotn, compta tenu de la condition et da la nattat* da l'axamplaira film*, et en conformity avac las conditions du contrat de fiimaga. Laa axamplairas origlnaux dont la couverture en papiar est imprimAe sont filmAs en commenpant par la premier plat et en terminant soit par la darnlAra paga qui comporte une empreinte d'Imprassion ou d'iiiuatration. soit par le second plat, salon la cas. Tous las autres exempialres origlnaux sont filmte en commenpant par la pramiAra paga qui comporte une empreinte d'impression ou d'illustration et en terminant par la darnidre page qui comporte une telle amprainta. Un das aymbolas suivants apparaitra sur la darniAra image de cheque microfiche, selon le cas: la symbols -^> signifie "A SUIVRE ", le symbols V signifie "FIN". Maps, platas, charts, ate, may ba filmed at different reduction ratioa. Thosa too large to ba entirely included in one axpoaura ara filmad baginning in tha upper left hand corner, left to right and top to bottom, aa many frames as required. Tha following diagrama llluatrata tha method: Las csrtes, pisnches, tebieeux, etc., peuvent 6tre filmte A des taux de reduction diffArents. Lorsque le document est trop grand pour Atre reproduit en un seui clichA, il est f ilm6 A partir da I'angle sup6rieur geuche, de geuche d droite, et de haut en baa, en prenant la nombre d'imegea nAcessaire. Las diagremmes suivents iilustrent la mAthode. 1 2 3 1 2 3 4 5 6 t it I ¥ K'^} >■' »i.* i,' 'i ^44 *E ^ *. ,a.< , •>' ''. /. ^. A). U, AN ABRIDGMENT or SMITH'S ILLUSTRATED ASTRONOMY. DESIGNED FOB THE USE OF JXJNIOR GIL.i^^®E® IK tBE' PUBLIC OR COMMON SCH06tS, ^ TOXIAM WABWIOK, WELLINGTON STREET. BAST* 1876. NOTICE. Thb following treatise is intended to inolnde a systematio «zpo8iti(m of the appearanees and laws of the heavenly bodies, as fMr as is praotioable withont the aid of Oeometry, Algebra, and the higher Mathematios. Several diagrams are inserted, whioh will be acceptable, both to teachers and pnpils, in illustrating the. general princi- ples of Astronomy, which, without iUnstrations, are deprived of much that is pleasing to the eye, and instmstive to the imderstanding. I. N % I ■•""wmi GEOMETRICAL DEFINITIONS. ies, >ra, ble, noi- ved the The Teacher should require the Pupils to under- stand the following Geometrical Definitions, before they are aUowed to proceed with the following Lessons: — A atiMighi Line is the ■horiaft line that can be dtmwn between any two points. A Burfaoe i» that which has length and breadth ; bat no thiokness. A Plan* li a itraifllit, even raxfaoe. The jdaae of a eimle, i» ^« mr- laee eontained wit&niti and continued ont of it on all lideiL indefinitely. The top of a xonnd oenti^ table, may be JMdd to repreient the plane of • cimle. PomlM XifMt axe linei eontinned in the same diveotton, and at the same distaaoe fkom eaeh other. Th^ may be either straight or carved lines. ,. ,, . ., ^ Cirele is a; plaae'flgnrei bounded by aotttviklUJM, every par^ is equally distant from the centre. S^ IHmmttmrofaCirtlU is a straliht line, passing through tlie centre, and tendboating both ways by the mroumf erenoe. TTke Oiiviui^arwwe 0/ a Olrsla is the carved line which bounds it. Th» OimmfmnnM of entry OireU is supposed to be divided into 860 equal pttts. called atureu; each degree, into 60 equal parts, called uMimtUt, and each minute into 00 equal parts, called eeeondi. mt§naMu9cfa dreU is a straight line, drawnjrom the centre to the otrevmfiBvenoe. ^ QiiadmMi* is a quarter of a circle, and contains 00 degrees. A B mM Hre U is the half of a drde, and contains 180 degrees. An AM0U is formed by one line, meeting another, at a point. 4 JM0M Jngleis an angje which contains 90 degrees, or a quarter of a An AmiU AngU is an angle whl«h contains less than 90 degrees. . 'li #' IV GEOMETRICAL DEFINITIONS. ^ An Ohtute Angle is an angle which contains more than 90, and leav than 180, degrees. Parallel, or Ooncmtrie Circle*, are two or more olrolei drawn arowid the same centre. fMIAUIL UNtS MNDENTMOailiaUt and !••» D aronud ABRIDGMENT OF S^mW» §\luU»UA ^ttttmm^i. LESSON I. Qi7B8Tioir. What ia ihe body palled npon which we live ?: . ,^| Answer. It is called the Earth, or World. *^ ' Q. What idea had the Ancients respecting the shape of the earm ? A. They believed it was an extensive plain, rendered uneven by hills and mountains. Q. Why did they think it was an extended plain? A. Because they formed their ojpinioDS from appearances only. ^ ^ Q. Did they believe that the earth had any motion ? A They did not; they believed that thfii^. ei^h rested on a solid, immovable foundation. \ ^ ' . [They very nitnntUy came to this oanoliiaion, as th^ were entirely ignorant of the laws of attrsetion or gravitation. 'th»y beUeted n the earth were to torn over, that every thing wotda be preiBipitated from its snrfsee. J Q» Had they any definite ideas veepiBcting what held the eatdmpf . - A^1!|l0ir views were very vague and unsatis- [Thflve have been manv absnrd ideaa'adyinneed, at dUliBrenl ages of the wwld, as to what supported the earth. Some snp- 6 ABRIDGMENT OF SMITH'S poMd it to be shaped like a Oanoi, and to float upon the waters ; othen, that it rested upon the back of an EuupbakTp or huge Tubvli; while acoordiugto mythology, Atlas sup- ported it upon his shoulders i bnt, what kept the waters in their plaoe, or tipon what ttie Elephint, Ttitrttoi or Atlas stood — ^this was a mystery th^ oouu) hkykb soxiVi.] Q. Did they believe the earth extended the same distance inalldirectionB? A. They believed it to extend much farthei; frotiircMktiiOwefltlhaiif^cttiiiiortlktdaouth. ^ [Thqr observed that in going east or west, on thersame parallel of latitude, no ehange took plaoe in the appearance of . , the heavens; but in going ncttth or south, on the same meridian, every sixty miles caused a difference of one degree in the eleva- tion of the pole, and in the position of the cides of daily • motion of the sun and other heavenly bodies; therefore they concluded that the earth Was very long from .east to west, but oompairativelynarrow from north to soutii. From this originated the nic of the mils longitude and latitude'; longitude mean- ing lepgth^i and latitude, breadth.] Q. Whatideashad they respecting the motions of the Bi^, mobn/tt&djltitfs? ' '* . . A. They jampposed that they revolved around the! Mith, j&oin east to west, eveiy day. Q. What was this system called, that supposed the eartii to be at reni itt thil centre, and all thd heave^y bodied to reipolvi roond it t A. The Ptol^naic ♦ system. |Ptplimy assertedthatttiesun,mooli,pkncts, andstarsrevol- , ved arouim tiiC earth, from east to west,eyevy;24 hoiirs ;and to MiMJunlloIr flieiir not falling up<^ the emti, -#heh tliey passed over it, he suppeeed that they ^ere each fiked in a scpwiic hollow ^arystafune edobe, fpe within the other. Thus the moon ffd-iM th^ ilrst ; Mereunr in the second ; Venus in the thiisd ; m 10 U the fourth ; mta in the fifOi ; Jupiter in the aix^ ; Saturn iii iShe seventh ;—<(the planet Qcprsehel was not kuMm at this timej— the fixed state in the eigbUi. He supposed the Istiis Ho be m one sphjore, as they aire hepi in the saahepiMticGts with respect to eadkother. To permit the light of the stars to pp^s down to the earthi he 8uppo]Bed these sriieres or globes #ei^ i^ernMly Ctea^ ior transparent like guisk TM^poW^ which moved these spheres, he. supposed, was mmimntimtfid , ^rola above the sphere which contained ih» stars.} *Toie>ma^-i^ ILLUSTRATED ASTRONOMT. LESSON II. QuisnoN. Everv one id oonsoiotui thai the san, whioh rUes dally in the east and Mte in the westt is the same body ; where does it go during the night ?. .Answer. It appears to pass round under the earth. Q. When we look out npon the stars, on saeoessive evenings , they ai^ear to have a deinite position with respect to each other, and a westward movement like the snn ; what motion do they aj^pear to have from their setting to their rising ? A. They appear to pass under the earth. Q. Ftota the north to th6 south point of the heavens, there is a eontiimons an of stann and in their passage nnder tire earth they are not at all disarranged, what can yon infer froni thisM? A. That they pass completely around the earth, and every thing' attached to it. Q. Wb see no body at rest that does not touch some feat- manent support, bvt we see bodies i|L motion ^pported fer differei^ lengths of time without resting upon any other sur-. lace ; if the earth is hnng npon nothing, is it probably at rest ? A. It is more probable that it is in motion. Q. If we throw a ball, does the same side always remain 'fov#ari9 A. It does not ; it turns oyer continuously. Q. Whatdo we call the line round which it tarns? A. Its ft^ds, Q. If a fly were on the ball, would distant objects appear to him id b« stationery ? ^^ ^ A. They would appear to revolve around ite bal}, as c^eii as it turned over. Q. If the earth is moving in space, is it in accordance wUh the known motion of -ted i nary bodies, to suppose I^At Uie sajnefidt reiiiains £9rwwd ? A. It is not It is more reasonable to suppose that it turns on its axis, 8 ABUDOMCNT OF SMITB's Q. If the earUi iimiB, and we are carried round on itg rar- fikce, what appearanee mnit tbe gnn and diitant stars neees* sarily peseht ? A. They must appear to move around the earth in the opposite direction. LESSON III. QuBBTioN. Wbat other reason ean yon give for fhe earth*! turning? Answer. The stars are so distant, that their mo- tion would be immensely swift, in comparison with the motion of the earth, to produce the same effect. Q. Bat have WCbUot positive proof, and that too of different kinds, tliat the earth turns on its axis ? Ai We have.— 1. The shape of the earth, ele- vatkl iat the equator and depressed at the poles, can be aocpunted for on no other supposition. 2. A body at the equator, dropped from a great height, falls eastward of the perpendicular. d. The trade winds and ocean currents in the tropical regions are clearly traceable to the same cause. Q. If the earth is moving in space, does it proceed' in a straight line ? A. It does not; but it would do so, Wer^ it not attracted by other bodies. Q. What is the attraction, by which all particles ef matter tend towards each other, oatled? A. l^eattnustion of gravitation. ' Q. What Urge body, by its attraetldn, eausei the earth to rev<4Te fWM>nnd it la a carved line, A. The sun. ■r t ILLUSTRATED ASTBONOMY. 9 ( *' # ■I §. WbM othw limilAr bodies re? oWe around the son ? k. The planets. Q. What m»y we oall the earth, when ooneidered with regard to its eise, ehi^, motionB, eto. A. One of the planets. Q. What soience describes these characteristics of the •arw and other heavenly bodies ? A. Astronomy. LESSON IV. ASTBOHOMY. QussTioN. What is Astronomy ? Answer. Astronomy is the science which treats of the heavenly bodies. Q. What are the heavenly bodies ? A. The sun, moon, placets, comets, and stars. ' Q. Are ihey all of the same magnitude, or size ? A. The sun and stars are much lai^r than the other bodies. Q. Are they all at the same distance from the earth ? A. They are not ; the moon is the nearest, and the stars the most distant. Q. Do they all emit light of themselves ? A. They do not. Q. How are they divided in this respect ? A. f|:hey are divided into two classes, luminous and opaque. Q. Whatisalmninonsbody? A. 'It is a body which shines by its own light. Q. What is an opaque body? ' A. li is a body which shines only by teifiediing the light of a luminous body. #■' 10 iOiBIOQllENT OF SMITfi'S Q4 W^olh ve Ihe Imninoiu hodiea in the heftvens ? ■ A. The sun and fixed stars are luminQUB iiodi^. Q; Wiiidli are the opaque bodies in the heayenB? A. The moon, planets, and comets. Q. Why do the moon, planets, and comets appear lu- A. Because they reflect to us the light of the sun. Q. What is the shtqie of the heavenly bodies ? A. They are round like a globe or ball. Q. What do the sUn, moon, plAnOts, and comets constitate? A. They constitute the solar system. LESSON V. THE S0L4B SYSTEM. * ' Qi;«8inoK. How jure the bodies oonttitnting the solar jys- tem arranged? ^ Answeh. .The «un is placed in the centre of the system, -^ith the planets and comets -revolving around it at unequal distances. Q. How many planets are there in the solar system ? A. Thirty-six is the nupiber known at present Q. How are they divided with respect to their motion ? A. They are divided into two classes, primary and secondary. Q. What is a primaxy planet ? A. It is a i^Aet which revives around the sun only. Q. What is a seoondary.planet ? A. It Is a planet which revolves around its pri- mary, and with it around the sun. r j B^ K^^ <^ th^ se^^ W*^^^ 1^ 1 ILLUSTftATEt) ASTRONOMY. 11 Q. How many primary planets are there ? A. Sixteen ; eight being asteroids or small placets. Q. What are their names, beginning at the sun ? A. Mercury, Venus, the Earth, Mars, (Vesta, Astrsea, Juno, Ceres. Pallas, Hebe, Iris, Mora,) Jupiter, Siifturn, Herschel, or Uranus, and Leyer- rier, or Neptune. Q. How many secondary planets or moons are there ? A. Twenty. * Q, Which planets have'moons ? A. The Earth has 1, Jupiter 4, Saturn 8, Her- schel 6, and Leverrier 1. Q. .In what direction do all the planets revolve on tiieir axis, and aiH>ut)d the gun? A. From west to east. [Note.— In eiamining the Solar System, an arrangemejit of exl^aordinazy beaniy and harmony, presents ita^. The jSon, ' which is 500 times larger than all the planets, both primMy and secondary, combined, ooenpies the. centre, diffnikif^ li^ai and heat in aU directions. A onriovs and extracrdhiaiy law sef^ms to regulate the distances and motions of ati the planets. The following are some of their peculiarities, viz :— 1st, The Sun, which occupies the centre, revolves on i|B axis from west Xo east. 3d. All the primary planets reVolve around the Sun in the same direction, from ««»/ to Mu/. 8d. The secondaiy planets or moons, revolve around their primaries from west io east. 4th. All the plc^nets, both primary and secondary, revolve on their axis from w»/ to Mr/. 5th. The orbits of all the planets, both priinaiy and secpnd- azy, lie nearly in the same plane tA the Sun's equator. From this it will be seen that all the motions of ^ planets in our solar system are in one direction ; a circumstance whiol^ clearly demonstrates, that they originated from the same cause and are governed by the same laws. To this reptar)l4ble bar* mony in the movements of our Solar System, there is supposed to be one exception, viis.^ the retrograde motion of the BateUites of Uranus. But ,this fact has not been fuUy settled by Astrono- mers. For a more full description of the origin of the Solar System* see Illustrated Asbx>ndmy, page 47. 1 12 ABRIDGMENT OF SMITH'S LESSON VI. Question. How many revolutions has a primary planet ? Answer. Two; one on its axis, and another around the sun. Q, What is the axis of a planet ? A. It is a straight line, round which it turns. Q. What is the path called, in which a planet revolves around the sun ? A. It is called its orbit. Q. What is the plane of the earth's orbit, extended to the heavens, called? A. It is called the ecliptic^ Q. Why is it so called ? A. Because eclipses take place only when the moon is in its plane. Q. How many revolutions has a secondary planet? A* Three. 1st, the revolution upon its axis ; 2d, the revolution around its primary ; 3d, the reVoluti<>n with its primary around the sun. . Q. How are the planets divided, with respect to thdr dis- tano^fiom the sun ? ^ A. Into inferior and superior, according as their distance from the sun is inferior or superior to that of the earth. Q. Which ai^e the inferior planets? A. Mercury and Venus. ■ Q. Which are the supcgrior? A. Mars, the Asteroids, Jupiter, Saturn, Herschel, and Leverrier. Q. How many kinds of cotg'utiotion are there ? A. Two ; inferior and superior. Q. When is a planet in inferior om^undiion with the Bun? A. When it is between the earth and sun. I I anet? other f':, solves to the ILLUSTRATED ASTRONOMY. 13 I. Q. Wliat planets can be in inferior oonjtinetion ? A. Mercury and Venus ; also the moon. Q. When is a planet in superior conjanotion ? ^ A. When the earth and planet are on opposite sides of the sun. Q. What planets can be in superior conjunction with the sun? A. All the planets except the earth and moon. Q. When is a planet in opposition. A. When the earth is between the sun an planet. Q. What planets can have opposition ? A. The superior planets. 1 the LESSON VII. stxis ; , the ir dis- their that chel. sun? f DXAltBTaBB. Sun, ' Mereury, Venus, Earth, liar8> Vesta, Astroa, «funo, Geres, PaUas,* Hebe, Iris, Flora, Jupiter, Saturn, Hersohel, LeTerrier, Milei. 886.952 3,20C 7,700 7,912 4,189 270 unknowi) 1,400 1,600 2,100 unknown Magnltttdes ; the Earth being 1 It 87,000 79^000 86,000 86,000 1,884,472 A • • • • asooir Unknown. TtTT . '••••••t tt «t 1,280 1,000 80 80 Distanoeir from the San. HUM. 87,000,000 68,000,000 96,000,000 142,000,000 226,000,000 253,000,000 264,000,000 268,000,000 268,000,000 Unknown. It «i 485,000,^)00 890,000,000 1,800,000,000 2,860,000,000 BeTolufeUm on their axis. Dy«.hoara. 26 10 24 2SA 24i Unknown. 10 10} Aevolation sronnd fbe Snn. Tn. Dayi* 1 1 3 4 4 4 11 29 84 166 88 224 321 280 106 131 222 814 16 5 * Herwdiel eBtimated the diameter of eaoh of the astemidi to he under flOO inilei, Their great distanoe. extreme amaUiiMMU and nei;>uloas appearaaoe, rtnder it extremely diAoult to ascertain their stse with 14 ▲BI^IBailSNT OF smith's LESSON VIII. OENTBIFBTAL AND OBJfTBIFUGAL FOBOB, Qi^STzoN. "What is that force called witli which all bodies attract each other in proportion to their mass ? Answer. — The atiractidn of gravitation. Q. What is centripetal force ? A. It is the force which draws a body towards the centre round which it is revolving. Q. What large body, by its attraction, exerts a.centripetal force npon all the priniary planets and comets ? A. The sun. Q. What body exerts a centripetal force upon the moon ? A. The earth. Q. What bodies ex^rt a oe^tripetid force upon the other moons? A. Hie primary planets aropnd which they revolve, ^ ^. WBslis the centrifugal foroe of a heavenly b^dy ? A. It is. that force which moves it forward in its Ofbit. Q. Hfrw do these two forces cause the planets to move ? A. They cause them to move in circular oir, cilliptical orbits. [A.body projected 1^ tmy foro^would alwiiys move forward in a itraightline, aodwiththe suae velooity, unless actednpon'' by some other forqe. A.ba|l diajpihargei from a gun or thrown from the hand soon looses its projectile force by the resistance of the atmosphere, and is brought to the ground by the atlrae- tieu of the earthy or eenftripetal force. (FiaB.) These t«o fofoes can be well illustrated, (Su Fro. 1, 2,) by tying a stadng to^aballand swinging it around; the centrifagMfsroe imparted to the ball by the hand and by means of the string, oaoses the ball to move in a drole ; but if' the string should breakj the qentpifligd f«ree would carry it off in a stn^^ line, ^ the bs^ M «#ifttl»^ ^ Oia earOu The striii(^poi7«i^pMsto^|^ attramon of the sun in our soUur (systeni, which caiuMiUM i'K C( 4 1 el C( P a iLLtSTRATED ASIXONOMT. 15 1 pUunets tQ move in fegnlar oarrm arovnd the Mm, inslMd of B%niah% lines. If ttie ftitraekion of lb? pnn nr «en^i)eta| fox«e should oeue, the planets woifld fly off into 8|WMe In straight lines ; but if the centrifugal foroe should oeiise, Mii th0 eentri- petal force continue, the planets wotild immedJAtetjr 1»l\ into theson.] Q. Whatisaoircle? A. It is a plane figure bounded by a curve line, all parts of which are equally distant from the centre. Q. What is an ellipse ? A. It is an oval figure, represented by an oblique view of a drcle. [Art^^ api4 vM^tenCagita- LESSON XL ECLIPTIC AND ZODIAC. QuisnoM. Whatisiheebliptie? AmWJStL It is the plaatt of the ease's orbit, ^- tended to the heavens, and intersects the eqttino<|i'> tial at an angle of 23^ d^rcpi {ST Sa"). [MHe.—l% if Jhft <9P«a^nN^ of *b^^^ ftB lieaTens onoe a year, tfauM^ byihe mtleUmtW^'etimi anmnd tiie Sim.] ;H..u ;,: ;.:<. :J; /■ ' I .'J>*' s I ( . \ s i 1 / ( H ) 1 \ C ibe the .uvvw ' %^^ ^ . v<$ Ji. ■■r^l ■ If ILLUSTRATED ASTRONOMY. 19 Q. What is the equinoctial? A. It is a great circle in the heavens directly over the equator. [Note.—l% is the plane of the earth's equator eixtended to the heayens.] Q. What is the zodiac? A. It is a circular belt in the heavens, 16 degrees wide; 8 degrees on each side of the ecliptic Q. What great circle is in the middle of the zodiac? A. The ecliptic or orbit of the earth. Q. How is the zodiac divided? A- It is divided into twelve equal parts, called signs* or constellations of the zodiac. Q. Etow is the ecliptic divided ? A. It is divided iuto twelve equal parts, called signs. Q. How is each sign divided ? A. Each sign is divided- into 30 degrees, each degree into 60 minutes^ each minute into 60 seconds, &c. Q. What are the names of the constellations of the zodiac and the signs of the ecliptic? A. Aries, Taurus, Gemini, Cancer, Lpo, Virgo, Libra, Scorpio, Sagittarius, Capricomus, Aquarius, and Pisces. * Q. Do the constellations of the zodiac, and the signs of the ecliptic, occupy the same places in the heavens? A. They do not : the signs in the ediptie have fallen back of the constellations aboat 31 degrees. Q. Did the constellations of the zodiac and the signs of the eclij^tic ^ter oolrrespdnd ? A. They corresponded to each other about 22 cen-^ turies ago. 20 ABRIDGMENT OF SMITH'S Q. What is the cause of the faUing back of the signs of the ecliptic among the constellations ? A. It is caused by the retrograde motion of tha equinoxes. \Note, — ^Thia variation is eansed by the pole of the earth varying a little every year This motion of the pole of the earth is similar to that sometimes shown by a top, as it spins aroond on the point. The stem of the top will have a oironlar motion, describing a cone with the apex or top down. This eiroular motion of the pole of the earth is very slow, varying only W eyeaty year, and requires 26,868 years to complete a revelation — ^whioh is called the Platoyio or great year. The pole of the earth is increasing its distance from the north star, and in 12,900 years it will be about 47° from it ; and when the north star is on the meridian, it wiU be in the zenith of the nprthem part of the United States: but in 26,800 years the pole will have made a complete revolution— so that it will point again to the north star.] . Q. Upon what does the length of the year depend ? A. It depends upon the revolution of the earth from one equinox to the same again. Q. Does the earth revolve around the son in exactly the same time that it moves from one equinox to tiie same equi- nox again? A. It moves from either equinox to the same again seventeen minutes sooner, tnan ai-ound the sun. LESSON XII. QuBSTiov.* Does the sun appear to move in the heavens among the stars ? Answer. It haa an apparent motion in the eclip- tic, eastward around the heavens, during the year. Q. How is this appearance caused, as the son is in the centre, and-fkyes not move ? A. It is caused hj the earth's moving around the sun. Q. If the earth is in the sign Aries, where does the sun appear to he? A. It appears to be in the opposite sign, Libra, ILLUSTRATED ASTRONOMY. ^1 Q. As the earth moved around in the eoliptio, where does the sun appear to move ? A. It appears to move in the opposite part of the heavens from west to east. Q. Which sign does the sun enter, when the north pole leans exactly towards the sun ? 7 A. Cancer. (21st June.) Q. Which sign does the earth enter at this time 9 A. Capricornus. Q. Which signs does the sun enter, when the north j^ole leans sideways to the sun? A. Aries and Libra. Q. Which sign does the son enter, -when the north pole leans exactly from the sun ? fk. Capricoruus. (22d December.) Q. Which are the equinoctial signs ? 'A. Aries, 21st of March — Libra, 23d of Sep- tember. . Q. Which are the solstitial signs? A. Cancer, 21st of June — Capricornus, 22d of December. . . LESSON XIII. Question. How are the signs of the ecUptic divided ? Answer. They are divided into four divisionp, corresponding to the seasons. Q. W^oh ave the spring signs ? A. Aries, Taurus, Gemini. <). Whioh are ^e summer signs ? A. Cancer, Leo, Virgo. Q. Whioh are the autumnal signs ? A. Libra, Scorpio, Sagittarius. 22 ABRIDGMENT OF SMITH S Q. Which art the winter signs? A. CapricomuSi Aquarius, Pisces. Q. In what time do the equinoxes Sail baok throngh the • whole circle of the Zodiac ? A. 25,800 years. Q. What is thib time called? A. The Platonic, or great year. 9*"How is this motion catised ? A. It is caused by a slow annual change in the direction of the earth's axis. Q. What is longitude in the heavens ? A. It is the distance from the first degree of the sign Aries, reckoned eastward oh the ecliptic, the whole circumference of the heavens. Q. When the sun enters Aries, what is its longitude ? A. It has no longituda Q. What is the longitude of the earth at that time? A. 180 degrees. Q. When the sun enters Cancer, what is its longitude ? A. 90 degrees — the earth's longitude at the same time 270 degrees. Q. Wh^n the sun enters Libra, what is its longitude ? A. 180 degre'es — the earth's longitude degrees. Q. When the sun enters Capricomus, what is the longi- tude? A. 270 degrees — the earth's longitude at the same time 90 degrees. ILLUSVRAI^SD AST90N0HY. 2§ LESSON XIV. MEBCURY. QuBSTiON. Which planet is 'the smallest and nearest the sun? Answer. Mercury. Q. What is the diameter of Meroary ? A. 3,200 miles. Q. What is the distance from the sun ? A. 37 tnillions of miles. Q. What is its magnitude, compared with the earth ? A. It is. ^ of the earth's magnitucle. Q. In what time do^s it revolve on ite axis, or perform its daily revolution ? A. In about 24 hours. (24 hdurs 5 minutes.) Q. IniHlat time does it revolve around the Bun. A. In about 88 days. (87d. 23k 14m. 33s ) • Q. How fast does it move in its orbit around tha sun? A. It moves 112,000 miles an hour. Q. What ^ tho lic^t or heat at Mercury cou^f^^d with that of theeajr^h? A. It is about seven times as great. Q. Whatis elohgation^ A. It is the apparent distance of any platiet from the sun. o ^ i Q. What is thie greatest ell^g^tion of Mercury ? A. 30 degrees; .which may be either east or west of thasuQ. Q* W^l( ^ Merpui^ nevejr seen in superior coiyui^ction ? A: Because it is so much involved in the flight of the sun. « r / / Q. I)oH^ Merpnry e;i^perienQQ auy changes of aeapp^M ? , A. It doeii liot^ because its axis is perpendietikyr to ilusoiibit. iTIus ^uses the mm to be eontmuaily vertical at the equator. :. ,|) n^ 4- ^4 ABfttDGMSNT 01^ SMITB 6 LESSON XV. • ... VENU8. Question. VfhtLi planet is next to Mercury ? Answer. Venus. Q. What is the diameter of Venos ? ' A. 7,700 miles. Q. What is its distanee from the sun ? A. 68 millions of miles. Q. What is its magnitude compared with the earth ? A. It is about ^ of the earth's magnitude. Q, tn what tune does it revolve on its aids ? A. In about 23} hours. (23h. 21m.) Q. In what tkae^ dbe? it revolve around the Bim ? A. In 224 days. (234d. 16h.41m. 27s.) Q. How £Mt does it move in its orUt avoond the enm ? A. It moves 75,000 miles ail hour. <|. Whit is the oomporative light or heat at Venus ? A. It' is about double that of the 6arth/ Q. What is the greatest elongation pt Venus ? A. A.bout 47 degrees. Q. When is Venus a momiag star ? A. When it is west of the sun, and rises belbre.it. Q^ Whim is it an evening star? A. When it is east of the Bun, and sets after it. Q. Hdiir bug is Venus a morning or an evenii^g star, A. About 290 days. Qi Whir is Vehtts' * hiorniiig or an eivetihig stiir 66 days lon^^ than Ihv time of its retblntion around ithesha? 'Au Be€irase the earth k iiSOTiiig a^ the sun the same way. i ? ILLUSTRATED ASTRONOHT. m LESSON XVI. QihisTtoH. How mvoh is the Ksi$ of Venus indined to that of its orbit? ANSWiat. 75 degrees. Q. When the north pole of Venus indines di^reetly towards the Sim, how tnany degrees will the axis point above thei^? A. Only 15 degrees. Q. How wide a torrid Zone does this make ? A. 150 degrees — 75 degrees on each side of the equator. Q. The tropi«ii are Irithin how many degrees of the pdles ? A. Within 15 degrees. ' Q. This polar eireles are Within how many degreed of the eqnatoK? A. 15 degrees. Q. What i» the diameter of the polar oirdee ? A. 150 degrees. Q. Has Venus any variation of seasons ? A. She has two summers and two winters at the equator, and a summer and winter at each of the poles, during the year. . Q. How does Venus appear, when viewed with a tele- scope ? A She exhibits phases similar to those of the moon. Q. What is th^ transit of a heavenly body t ^ A. It is its passage across the me^i'kUan., Q. Wh$t is meant 1^ the transit of Meromiy and VenDs ? A. It is their passage across thenun^s disci Q. What is Ihe #Mt of the sun or a plinet ? ^ A. It is |he circidar illuminated sur&co visi|>le to 1|S. 2IS ABRIBGItttllT Of lEDtTm'liI Q. How do Meronry and Venus appear when passing across the sun's disc? A. They appear like blade spots proving acirpss ihe sun. Q. What proof have we that M eroory and Vemii are'not l|UHaipa|is:ltQdii«s? . . ... -frr ,,! .M TWrfv/ ■■-^ A. When viewed with the telesoope they appear homed like the moon. Q. On whieh side of the sun. does the transit bogip ? 'i A. On the east side, and tenpinatea on the west side. .'.r,Ujti|>- Q. ! "What apparent motions have i|ie, Janets ? A. Three; direct, stationery, an4 retrognul^. Q« 'When does a pianet's motion appear to l>o diii^ ?, t A. When it appears to move from west to east among the stars. Q. When kaplaaot's motion said to boslatlojicffy? .. A. When it is moving directly towainis or fitom the earth. v Q.) ' Whente a phuiet'smetieii said to be^ retrograde ? ' a: When it appears to move backwards, or #oin east to west among the starst ifinrf. ^«v|4^« LESSON XVII. .,,..,,, SA9TMrDBPmiTimfB^ STO. QuBSTioiri' l/fhki ik tho disj^b of iSio eiDpyi ? AnsTWsb. It is round like ii globe or ball^ it little flattened «A the pc^g. f«i.trt; Q. How do #e know the oartb) to bo tonM f A* Isi UllVigkton hftV^ satll^ rotiiid it, bjr a continued westerly or easterly course. 2d. The ILLUSTRATED ASTBONQMT. n jbop-mast of a shipooming in horn the sea, always ap- pears filBt 8d. The earth's shadow upon the moon, m a lunar eclipse, is circular. Q. In what msniier do the inhabitants stand upon the earth? A. They stand with their feet directed towards the centre of the earth. Q., What do yon understand by the tenns upward and downward? A. Upwards is from the centre of the earth, down- ward is towards the centre of the earUi. . Q. What keeps the inhabitants, etc., upon the surfaoe of the earth? A. The attraction of the earth. Q. What is the axis of the earth? A. Jt is ihe straight line round which it performs its daOy revolution. Q. Whi^) are the poles of the earth? A. Iliey are the extremities of its axis. Q. How are the oiroles of the globes divided? A. They are divided into great and small. Q. What is a great oirole ? A. It is a circle whose plane divides the earth into two equal parts, called hemispheres. Q. What are the poles of a great circle? A. They are t^o opposite points in the heavens, equally dktiuit from all ports of the ciroumferenee. [A^.—Tlie pedes of the herizon anth^Ztt^A tM&MkUr,- The poles of the equator, or eqninootial, are those points whare the earth's axis, if prodaoed each way, wotdd meet the heavens. The north star is situated in one of t^se points.] Q. What is a small circle ? A. It is a circle whose plane divides the earth inftp two unequal parts. • 28 ABBIDOMBNT OF SMITH'S Qv WUeh At* the great oirolMiuedia Astronomy? % A. Equator, Meridiaii> Horizon, Ecliptic, and Equinoctial. , [AWtf.oThe equator divides the earth into northern A^id lonthem henuBpherefl— the meridian divides it into eautom and western hemispheres, and the horizon divides it into upper and tower hemispheres.] Q. Which are the small circles, used in Astronomy f A. The tropics and polar circles, paitdlels of lati- tudes, altitude and declination. [A^A— Purallels of latitude are small circles parallel to the equator— paraUelB of altitude are small oirelek wurallel to the horizon — ^parallels of declination are small uucles,on the celestial globe, parallel to the eqninoctiid, and correspond to parallels of latitude on the earth ; or if paraUds of lalStiide oik the earth should be extended to the heavens, Uiey woild ttien become parallels of declination.] Q. What is ^e equator? iA!. Itisagreat circle, whose plane divides the earth into northern and southern hemispheres. Q. To what is the plane of the equator perpendionlar ? A. It is perpendicular to the earth's axis, and equi-distant from the poles. Q. What is the meridian of a place on the earth ? A. It is a great circle passing through the plfice, and the poles of the earth. Q. Into what does the plane of the meridian divide the earth?' , :.5.^ i.^.^,.. ^,.j . ,,•> , A, Injbo eaipteni and western benuspheres. Q. What is lihe latitade of a plaoe on the eavth ? • A. it is its distance from, the equator, north or so^ith. Q. On whatisitflMasnred? A. On a meridian, Q. How, fiuFfis latitade reckoned? A. I^ttttfty degrees. • wmm ILLTTSTRATED ASTROirOMY. Q. WhatplaeeihATeaiiietydagreaioflftliiacle? A. The poles. Q. What are the tropios? A. They are two small circles parallel to the equator at a distance of 23} degrees north and south of it. Q. What are the polar ciroles ? A. They are two small circles one around each pole/ at a distance of 28| degrees from it. LESSON XVIII. QuBSTioM. Which in the first meridian ? Answer. It is the meridian from which longitude is reckoned. Q. Which meridian is generally nsed in this opnntry as the first meridian ? A. The meridian of London^ Q. What is the longitude of a place on the earth ? A. It is its distance east or west of the first me- ridian. Q. How far is terrestrial longitude reckoned ? A. It is reckoned 180 degrees, or half round the earth. * ^ ; Q. What is the horizon? A. It is a ^eat circle which separates, the vifi- ble heavens from th^ invisible. Q. Whait ate ^e eardinal points of the horizon ? A, ipTortl^, l^i, Soiith, and. West Q« . How nuun^r hoilzons me« there ? A. Two; the vi^1»leaiid the rational. • • 80 AJBHNnfBNT OF SMITHES Q. WhAlUilik«vitibk«rMniiU6li0i!iion? A. It is that cirde where the earth and sky ap]iear to meet, j Q. ll?]|ftli la the r^iooal hforis^on ? : t A* it iB « ffreat circle, parallel to the visible hori- zon, whose j^ane passes through the centre of the earth. , Q. Intpwl^aidoeiUcliTidBih^ earth? A. Into liipp^r and lower hemispheres. . i, Q. Ib the rational horizon above or below the yirible horison. A. It is below the visible horizon. LESSON XIX. ' <)Viinox Bo aU plaoee on «he earth have the nme liori- ^SfVj^ Tl^v do not; if we change owrpli^se on the eaith, the norizon (manges. Q. What are the cardinal poiiltji hi the heavens; or the pfdes of the, horison ? A. The zenii^ and nadir. Q, What is the zenith ? A. It is that point in the heavens directly over our heads. ' Q. l>o all places have the same zisnith ? A. They do not; every place has a different zenith. tj. tlliiitto^Blaairr A. It is that point in the heav^hs 'which is 6ppO' site to the Mkiilli ^'dii^tiCtly tttiddt oolr feet. Q. Are the zenith anil nfeilter flil^ jfoksk lk 'ih^'h^KKvetiB ? A. They are not; ikei^ ittaate iiiebittiAete i^vdu- tion in the heavens every ^4 hoiirs. A. , It is ita l^iglit or dista^nce from the horizon. 9^ What it the pdUtf AbrtMiee of » hMttnly body f A. It in its distanoe from the pole. Q. Who ttrefh# ttitipodiB? A. Tiiose who live on, directly opposite sides of the earth. Q. who are the antoeoi ? . ; , : A. Those who live in equal lati^nde., on diiecUy d^iposite sides of the equator. Q. Who are the perioeoi ? A. Those who live in equal latitude, on o{^)oeite sides of the pole. LESSON XX. SABTH AifD StiAaom. Quaanoii. What ia the ahape of the e^arth ? ANSWEIt. It is round like a globe or bid), a little flattened at the poles. j mw hi ; Q. What is its position in t^e aolarajntem? A.. It js the third planet fronn the sun. Q. What is the mean diameter of the eartl^? ; , A. 7J192 piles, equatorial diameter 7,926 miles! p<^ di^iet^ 7,«I9^ MM) . Q.. Hpw ^neh greater ^ the equatorial than tl|e pqlar A. About 27 miles. I|. Whit oa^iMS this e^tiiitotiil ffiamnter to his gr«ai^r tiiim thepdar? A. It is caused 1^ Hie revolution of ihe eattU on its axis. [As the groftter portion of the snrfoee of the earth is covered wi^ water ; and as the ««rth revolyes on its axis ; the water 32 .'ABRIDQifENT OF BMI1H'& recedes fronii tM pole« towluds the eqmttor, m&fti} ite.lendency to run iMok towaidfi the poles, just baluioes thtt effe|i^ o| the oehirifti^ foree. This oantes the eanatciHal diameter to be gre(fttar than the polar. II jUbe earth mould sU^. t^t^triag on its axis, theirater at the equator would settle away towiurds the poles, until fh^ had asramed the iorin of a gbbeas iiear as possible. Thus large portions ol land in the ton^ aone, wl^eh are now covered hv . the ocean, would be leu dry, and ndweontinentf Atid islands would be formed.] , : ' , , -Iff t Q. What is the mean distanoe of the earth from iHie sun 7 A. Afbont S^5,000,000 miles. [The mean distance of a planet, is the distance it would always bo from the sun, if its orbit should be reduced to a tirne oirole.] ijr^Wiiat is the specific gravity of the eMrth^^','^^^^^^ ^\ A. It is 5 1 times the weight of water. (5.48.) Q. In what time does the earth revolve on its axis, or per* form its diurnal revolufion ?/, v>>;^^»H a A. In 24 hot^nk (In 23 hours 56 minutes; a8 seen from the stars. . .mwfi-/h ; and th6 shade , Q.;'\niicbwi^7cloe8 it, revolve? A. From west to east. Q. Whatcavt^dftyattdniigtht? A. The light of the sun Qjfiiiiieb of the earth daiislBfii night. Q. How great a portion ofthee|Urih is continnii^j in the light of the >^nn? ^ Al' One luUf ; the other half being in the sljkl^^ of tAie earth. i; *^*'» ^..wf* >• . Q,l yjhtX 4ees tilt rcfTplulion o| the earth upon its axis cause? :.|,.,. ,, ■^•A ., ', LESSON XXI. QvMnoN. As the ear^ tams upon its axis, what effect is produced? Answer. The sun is continually lisingidpliiees in the west, and continually setting to {d^ses in the east. Q. In what time does the earth revolye around the sun, or perform its annual reyolntion f ' A. In 365 days 6 hourd. Q. ; 9ow fiwpt.dpes it Daciiye in its orhit arovmd the son 9 i^. 68,(K)Q jpiiiles an hour. Q. How are the changes of the seasons caused ? A. They are caused by- the ^earth's axis; being in- dined. to that of its orbit, and its revolution around the sun. ' * % How mAtty degrees is thd ^Arth's axis iitdliiie^ to Ihat of its orbit? A^Tweot^three degrees and a half. (23° 28'.) Q. Is the direction o( the earth's a:|is chahged during 'the year? -ij'.jonn'!' * ;'^! i *> A. Its change is so slight that it may be conMdered 80 pointing to the same placeMin the heavens^ Q. Wii^n cioes Uie noitii pole kan direetly towards the sun ? A. On the 2lst of June, eaUed the summer sol- stice. ; • / « Q. How many dagMM doM it lean towaidathasiin ? A. 23} degrees ; and the sun is veiiiisal ?^. ' degiees north of the eqwitor. , b ^«w Qk What seasoDS ddlBs this produce ? lA^ Bonmet m tb^ ner^hem hemist4ievb'> li&d winter in the southern. jt>Utii|»j ■ ••'■ - d« AJBBtDGtM BNT OF SMITH S Q. When does the north pole lean directly from the sun ? A. On the 22d of DejB^mber. called the winter Bolstice. ' ' ' ' ' Q., lllTlienlbeiiQrthj^ole lewis lK>mtbe»9i]iifWhfii«re.t^^ seasons? ^: feajufewf q si A. 'Winter in theno]!thernli6misphiere,'aiidstim- mer In tlie iotttheiDn; >' m xit if i LESSON XXII. n ai »n ' -J- ' ,j-- -■'' A QuBSTioiT. What are the oardmal pomts of the eoliptio ? Answer. Yht eqtiinoctial atid solstitial pbi^ts: Q. At what points of the ebKpUc is ike ettrth at the nme of thesolstioAft? Il^io6■ A- At itbe splBtjl^al points.; Qu Through liow moeh of its oviril does the earth passi in moTing fr< m one Solstitial point to the other ? i d; ^. QnQ JbaLf of it^ prbit« or from one pijl^ of ,Uie sun to the oiner. Q^ What are fhoiiB two points called, hilf tra^^ bet#een thesoktitial points? A. The equinoctial pomts. Q. WaqraMthsgrsbialM? A. Beoanfleywhdn tiie' earth i» in these points, the am is yerUiei^iMtbe «quiNt*,f^] ^ '^ v ^ iJ^ }^)iiumrmdemii^4Q thi sim, ibfitiMfrbciDg vertical at the equator. jrv:HiMim yiU m 'v^trbi ILLUSTRATED MTRONOMY. M ' from the sun ? I the winter >> wluMk are the /■■■ »..-,■ re,attd«ttm- Wiy between fW)illt8, the th%ii«th# Q. When the north pole leans towards the Ban, why is summer produced ia the VQiihem hemisp]»ere? / A. Because the rays of tthe wn stril^Q iti m^re directly than in winter; cpnsequently^ thj9y ^e not spread over so great a surface. Q. When the north pole leans firoxp the 9UQ,,iir]Mr is wifiter produced in the northern hemisphere? A. Because the rays of the sun strike it i^o oM- quely, that they spread over a greater suriace t^ati in summer. Q. At what points do the ecHpiio and equiUo6tial intersect each other? / A. At the equinoctial points. Q. At what angle do the ecliptic and equinoctial' inteifitoot each other? A. 23J degrees. Q. Sow far art the solstitial points, from thei equinoctial pomts? A. Ninety degreea li / LESSON XXIII. Question. What is Mars? Answer. Mars is the fourth planet irom i)^p sUn. Q- W3ba^ ofm yo^ say of, its sia;© ? , , , , ', , ; A. It is the smallest, except Mercury aod the asteroids. Q^ "VifJ^^t is i^i 4i«m^ter ? ^ A. 4IS9 miles. ..,,,5 .. i; Q. What is its distance, froi^ the pu/i? : v . < .At l^?miHi()ijsof wiW ;|n /mIT # ..fQ..;V^|i.itpj^ . A It is about one seventh of the size of the ealrtk> S6 ABWDOlfBOT OF anTB's Q- ^ what Urn* doaii i* .—1 ^ in about 24ihoun.. 24h.39M.2a.) A. & on,Sye«r. 331 j, ™'" «"»*«>• ""? • A- S6,ooo aiies an hour. A. About 30 degrees, (30' 18') ^' ^**««*y longer? evolving ru.^XluS'"'^ '^" ''^ -^ y<^« .» Alt»ppeareofa,«dfie,ycolor. L LESSON XXIV. QiwsnoB. How don ]ir.» ■AWSWJSR. OutUnm nf -^ «««*« *«*dfatfae»^^*^ •PP^"* contitiente aad the imtaJ<3''S^»^™^''y «»Kri«ing p«>brt„y ^^^ . . . t ( r . ILLUSTRATED ASTBONOMT. 37 usleaaiowArds sem iAihOie Q. Does Mars present different phases ? A. It sometimes appears gibbous. Q. When does a planet appear gibbons? A. When we can see more than half, but not the whole, of the illuminated surface. Q. Does Mars ever appear homed like the moon ? A. It does not, because it does not pass between us and the sun. Q. What other appearanoes does Mars exhibit when viewed witii a telesoope ? A. Bright spots are seen alternately at the poles. Q. When do these spots appear? A. When it is winter, or continual night at the poles. Q. What is supposed to be the cause of these spots ? A. Snow and ice, which has accumulated at th^e poles during the winter* Q. Do these spots oontinne through the yjear? A. They entirely disappear as the summer ad- vances upon the poles. Q. What amount of light and heat has Mars ? A It has about half as much as the earth. LESSON XXV. JUPITMB. QuSsTiON. What is Jupiter? Answer. Jupiter is the largest planet in the solar system. Q. ' Hdw many times larger is Jupiter l^an the eiurih ? ' A. It is 1,280 times greater. ABBEDOMSNT OF smith's ^ Q. How fiur is Jupiter from the Btin 9 A. 485 millioos of miles. Q. What is its diameter ? A. 87,000 miles. Q. Whioh diameter is the greater, th^|iolar or eqtiktdiiiA t A. Thid ecjuftiorial diameter is 6;000 miles g^ealier tliaiii the pouff . Q. "What causes the equatorial diameter iso much to ex- otfW' the polar? A. The quick rotation of the planet on its azfe. Q. In what tiine does it revolve upon its axis ? . A* In about 10 hours, (dh. 55m. 56s.) Q. In what time does it revolve around the sun ? A. In eleven years, 314 days. Q.: I Hx^ &•! doeS'it moye in ita orbit around the son ? A. 30,000 miles an hour. Q. How mao(^ moons has J[upiter ? A. Fouiv Q. Has Jupiter any ohange of seaiRittsi? A. It has no change of seasonsi Q. V^y jid iii^ raasottfrnot ddoiit^T A. Because its axis is nearly perpendicular to the plane of its orbit, which causes the sun to be always vertical at the equator. Q. How does Jupitw appear when viewed with a tele- soopef A Light and dark belts appear to sanro^nd it Qi Whit airtfiiheligia belts? A lliey are supposed to be clouds^ whiokarvv ihroirQ.4>^to P9»nikUd^^^^^ quick rotation <»f the puinet, upon its atls, M^ ICtUSTBATSD ASTRON0IIT. S^ so xntioli to ex- Q.THiaiaMfbe dark belts S A. They are probably the body of the planet/scieh' between the clouds. Q. Do these belts always appear the same ? A. They change' frequently, ahd sdnietmifes the clouds break to pieces. Q. What is tlie Telocity of its equatorial par^; ill iaminff on its axis? A. 25,000 miles an hour. Q. What amonnt of light and heat has Jnpiter ? A. It has 27 times less than the earth. LESSON XXVI. SATUBN, (^xsnoN. WlmtisSa^un? Aky#ii£ li ii tlie largest plane c except Jupiter' Q. What ii^ its magnitade compared with the earth ? A.' It is aboui 1,000 times lanrer. ■ " / .f . >'■-■■ , . ® , . Q. What is the diameter of Saturn ? A. 79,000 miles. Q. What is its distance from the son ? A. 890 millions 6f miles. Q. In what time does it revolre on its tadk^ A. In about 10^ hours. (lOh. 29m: 16s.)' Q. In what time does it revolve arotmd the inti? ^ A. In 29 yeai-s and a half.^ (29y. 167d:) Q. How fast doejs it move in its oilnt aro#id ^iiokf A. 22,000 miles an hour. ' Q. Is there any change bf seasons itlSatiim'? A. Ther«& is ; bui il is yery% sl6#i as it? ti^es 40 JLBRIDOMBNT OF SMITH'S nearly thirty of our years, to complete a year at Satnm. Q. How mnoh does the axis of Satiurn lean towards its orbit? A. About 30 degrees. (28** 40'.) Q. How long is its day and night alternately at the poles ? A. About 15 of our years. Q. What has Saturn which surrounds it? A. Two large rings of solid matter like the planet. Q. What is their position around the planet ? A. They are directly over the equator. liESSON XXVII. QuiSTiON. Do these rings revolve with the planet ? An&web. They do, and in nearly the same time as the planet. Q. ' Are these rings oonneot#i with the planet, or separate ? „A. They are separate from the planet, and from each other. Q. What is the distance fSrom the planet to the inner |bg ? A; 19,000 miles. 4i|b^iiNir wide is the inner rmg ? A^ 17,000 miles. Q. How wide is the space between the rings ? A About 1,800 miles. Q. What is the width of the outer ring. A. 10,000 miles. ' ($ Sow tbiekaind these ringi? . 4. libboni :(00 miles. (Scihe^ say, ;I,000 miles,) . 8 »lete a year at ^TURN. lean towards its htely at the poles? '•>' •:v.i like the planet. net? bor. ihe planet? le same time as let, or separate? inet, and from ket to the inner g8? ^^ "'*^;^*<.. ^)<£i^^1^' il|k- •Jf"!^*- Jt ;fi^a^ it„ . i|i^ju 4 ^; H *n ^Jt- I 4 w< ILLUSTRATED ASTRONOHT. u Q. Are theM ring! nnifonn ? A. They are rough and uneven. Q. How many BateUiies or moonf has Saturn? A. Eight. Q. What is the position of their orbits? A. Their orbits, excepting one, are'cKirectly over the rings. /• Q. Does the son always shine on the same side of the rings? A. It shines upon each side alternately for fifteen years. Q. What amount of light and heat hMSi^turd? A. It has 90 times less than the earth. Q. What appearance has the disc of Saturn ? A. It has dark belts similar to those of Jupiter. LESSON XXVIII. HBB80HEL, OB UBAIfUS. Question. When was Hersohel or Uranus discovered ? Answer. In 1781. Q. By whom? A. By Sir William Herschel, who was a celebrated English Astronomer. Q. i*\ what part of the solar system is Hersohel situated ?; A. It is the fifteenth planet from the sun, and next to the farthest discovered. Q. What is its magnitude? A. It is 80 times larger than the earth. Q. What is its distance from the sun ? A. 1800 millions of miles. i2 . ABRIDQMENT OF SOIITH's Q. In wliai time does it revolve, on i|8axi»? A. It is not certidnly-knawn. .|{It has been stated at 1 day 18,IiQurs,, but tliere s^f^pi^a to M i^o, propf of it — Professor Nwliot!\ Q. In what tii^e 4<^$b it reyplve around the J3|m ? Q. How fast does it move m its orbit around thf.fnm ? Q. How will the light and heat at Bterschel compare wiih ^}ie,if|!w,|iitt^e.0arth?' A. They are 868 times less. Q. HowMiibi;nft0n8haB;MersQhel? A. Six moons , were seen by Mt Wm. Herschel, but only three have^ beieja s^en by Qth^r ^j^ofU)iners. 9. 4nj,ivi^icU|re(9tlon;do ith^se mqpns z^oy^in ^iTiOrliits ? A. They move from east to west, contrary to the motions of all the other planets, both primary and secondary. LESSON XXIX. Question. "When was Neptune discovered ? Q. "Who published the elements pf |(^ jpl|ii|a|»itta(Pid 4I« rected astrpnomers to the point in the heavens where it might A. >£i&veiTier> a celebrated French mathematician. Q. How near the point, where he directed astronomers to look, was it found ? A Within Qxi^dc^iGte. Q. Wbatisthe«liMn0tor;Qltblspl«Aet? A It is about 35,000 xnilaa. tLLtJSTttA^FfiD ASTRONOMY. m Q. Wliat is its magnitadQ ? A. It is about 80 times larger than the earth. Q. "What is its distance' firom the sun ? A. About 2,850 millions of miles. Q. In what time does it reyolve on its axi^ ? A. It is not known. r ' Q. In what jlomedoes it reyolve around, the sun ? A. In about 166 years. Q. How many moons has Leverrier? A. One ; and another is supposed to have been seen. ' " * Q. What amount of light and heat has this planet 9 A. About 9Q0 times Jess than that ,o;C the earth. r jQ^ . Aee ^e p^DCUury pla^ A.J(lie7f appe^rto be mhabitable. : EAMr.?r-Tbe praMBM of Qlouds:ipofli air and water, . ,^ rppOiKc s^Qceo^PB. o( ^e seaao;p8, as trdl lus day a»d night ; ine raitaUe amount of li^ zeoeived-firom the iun ; the eo- oompaniment of moons ; Uiespeetfiogra^ty of bodies at iiieir siirnoe ; all seem to indicate thai the primary planets are suitable residenoes for living beings. The ohly ol^ectionto this view is, the (^eienee -im the amount of heat reeaTodfrom 4^ ifn^ snpposiagititobe aooardingtotibteinTorseratio of the squares of iheir distanoes from the son. But we see fii^<»n the * differenoe of temperature on the earth, at the base and snmlnit < ^ ;^)igh,,mpiintaiQS» that the aotiial heat depends nn|Dh. ^pon the modifying oironmstanoes, as well as upon the diipDot frays of the sun. And we have reason to8iq>pese that the'ten^era- ^e of the other planets does not differ much from tli*t vl the 'eitfth. "- Vat instanoe the temperature of Mara, as indicated hy the fiQielling of its snow, ^and^that of Jupiter and Sataxn» as indi- jD^ed Kf the, smount of vapor in t^lr f^osphere, appear, to be sindiar to that of the earth. Meronry and .Venus are pro^ teoted frcMB the»direol rurs of 4beenn bjy dense douds. Causes unknown to us may, and probably do. modify the temperature of all the planets in a gi^ter or mss degree, suffiQeiiwr so* for pfiWimalUJe.] M ABRIDGMENT OF SMITH S LESSON XXX. MOON, Question. What is the moon ? Answer. The moon is a secondary planet, revolv- ing around the earth. Q. Is the moon larger or smaller than the earth ? A. It is 49 times less than the earth. Q. What is the diameter of the moon ? A. 2,180 miles. v-t .,r Q. What is the specific gravity of the moon ? A. It is 3| times the weight of water, (3.37.) Q. VthtA yr. its mean distance from the earth ? A^ Two hundred and forty thousand miles. Q. In what time does the moon revolve aronnd the earth ? A. In about 27i days, (27d. 71i. 43m. lis. 6.)- - Qw In what time does the moon revolve upon its axis ? A. In a^ut 27f days, or in the same time ihlit it revolves around the earth. r,Q* /Wliuit is the result of the moon's revolving npon its §^ aiid (uroiind the earth in the same time ^ ^ A. The same side of t&e moon is always presented U> the earth. ' ' Q. Have we ever seen the opposite side of the moon ? A. We have ftoi Q. What oanses the moon always to present the same side to the earth? A. It is supposed that one side of the moon is more dense than the other, consequently the centre of gravity is not in the centre of the mooa Q. ^What is a limati6n» or lunar month ? !A. It is the time from one new moon, to another. ILLUSTBATED ASTBONOMT. 45 anet, reyolv- earth? i? >(3.37.) miles. nd the earth? lis. 6.> nita axis ? imethiitit ing upon its 9 presented le moon ? be same side le moon is the centre another. Q. What is the length of a Innation ? A. About 29J days. (29d. 12h. 44m,) Q. Why is a lunation longer than the time it takes the moon to revolve aroond the eurth ? A. Because the earth is reyolving around the sun at the s^me time. LESSON XXXI. Question. \; ^ is the length of the days or nights ait the moon ? Answer. About 15 of our days. Q. Which way does the moon revolve aroond the eajpth ? A. From west to east. ' Q. If the moon revolves from west to east, what causes it to rise in the east ? A. It is caused by the earth's revolving on its axis the same way. Q. Does the moon rise the same hoor every evening ? A. It rises about 50 minutes later every day. Q. What is Uie cause of its rising 60 minutes later every day? A. It is caused by the moon's daily progress in its orbit from west to east. Q. What causes the phases of the moon, from new inoon to new moon again ? A. It is caused by the moon's revolving around the earth. Q.- When is it new moon ? A. When the moon is between the earth and sun, and the dark side is presented to us. Q. When is it full moon? A. When the moon is upon, the opposite side of the 46 j^^uD&itmrr ov Bmra^s earih from the Bun^ and the iUuminated dde; is pre- (tented to us. ' » ' Q. 'How rnnoh greater is ihe light of the s^a fhazi^ that of the ftiU moon ? ^^.''SCiO^^ea times greater. Q. When are the son and moon in quadrature ? A. When they are ninety degrees distant from each other. Q. How much' of the illuminated side of the moon is yjai]^ ;to us wh<>n i^ 4s in.q^a^Jrati^e ? A. One-hAlf. Q. How much laxg^ is the sun ihan the moon? iA- j7i)jniiJyUoii» of toes grei^ Q. Why does the moon appear as large as the. sua? ,.A. ^Sff^iise it is fowThiin(te€id, times, ;n©ar^r tanp than the sun. > <>» im^i ; LISSON XXXII. QuBippif. , ^as the mooi^ lu:^ alimqpp^iere ? Answer. Very little, if any. £Q^ SfUa^Mi tke appeaKanae of the- moon,'jnliea. viawed with a teleapope ? •^ ,j;t fi^ljew fiOY^reci w\^ %ht.^d ^w^k sjjots of various shapes. i iQ* 'Ffh^k iaiha cause of this appearanee*? A. It is caused by the mountains, plains ^nd- val- leys in the moon. ti). Wibat are thei light spots ? A. Mountains and elevated land. Q. What are the dark spots ? A. )Plain8,^vaill^y8^«to. tLLtraTAATAD AATBOHumt. Q. iSaatbf moon a^yooeftn, s^as, orjaxgejl^odiespf WftWvi? A. Not upon the side towards the earth. Q. If 70a .were living upon. Uiis side of the moon, what ^pi^d ,be;the f^ppearapjoe of the cjax^ ? A. The earth would appear jyk^ a ^fe sM^^^amy moon. Q. . How m|ioh l|tfger ;t|iai^ *he ^nppn f^ppj^i^i to, i» ? A. Thirteen times grQii«ter. Q. In what time would the heavenly bodies appear to revolve furonnd the mgon? A. The stars would appear to irev^^Ye an .27J i4*ys, the sun in 29} days. Q. lJ<^tu,thepihapeof tl^e.mciO)n'spi;)4^ A. Elliptical, or one diameter greater ; than the other. <). What is apogee? X It is the point , in tJiiei orbit of ^e moon, far- thest from' the earth. Q. WhatiaperigQe? A. I|iis the poi,i;it in the orbit of tfte m9op,.|ie,j|rr qgt jbp ft^Oj ^irth. , * the principal ones, decisive marks of volcanic stratification. ^. ^ng from successive deposits of deoted matter, may bedistir ^dy ti.v)ed with powerful telescopes. tiie moon contains no Is ge bodies of water, such as oceans, seas, etc. ; at least, not upo-:. ^e side visible to us. If there are any, the!f must be upon the opposite side of the moon, which is never presented to us. The moon also has very little, if any, atmosphere ; at least, none of sufficient densi^ to refract the rays of light in their passage through it: owing to these two circumstances, there are no cloiidB fioailng around the moon ; if there were any» thev would at times be visible to us, but none have been observed, li presents the saniiB appearance that it did 2,000 years ago; no WM of Tcffetition «r ehange of seasonii faM be«n obsertedi efirjr ILLUSTBATED ASTBONOMT. 49 16 aarvest thing appears solid, desolate, and XL. ■ foi sappcxrt of imimal or vegetable life. WEether the materials, of which the moon is composed, are ox the same nature as the earth, we haye no means of knowing. It has, howerer, been ascertained that its density, compared with the doisity of the earth, is .616, or a little more than one-half; conse4tientiy, the materials of which the moon is composed, are about one-half as heavy as the same bulk of the earth. There being little or no atmosphere about the moon, the heavens, during its daytime, have the appearance of night to the inhabit- ants of the moon, when they turn their backs to the sun ; and the stars then appear, as bright to them, as they do in the night to us; for it is entirely on account of the light which our atmosphere reflects, that the heavens appear luminous about us in the day- time. If our atmosphere were removed, only that part of the heavens would be light, in which the sun is situated ; and, if we turned our backs to the sun, the heavens would appear as dark as night. The light which the full moon affords us is very small, when compared with the Hght of the sun; it being 800,000 times less. It has also been demonstrated, that the light reflected by the mooi. prpduces no heat ; as its rays, when collected by the i^d of the most powerful glasses, have not been perceived to produce the slightest effect upon the thermometer. IS THE MOON INHABITED f Fbom the physiojal constitution of the moon, it is evident that the moon is not inhabited; at least, by beings constituted lUce ourselves. The moon having little, or no atmosphere, we could not iaxist upon its surface for a single hour, ev«n though provided with the pwer necessary means for Our ezktenoe : nevertheless, this is not positive evidence :that the moon is not inhabited. The same power that called the moon into existence, could as easify consti- tute beingB fitted to inhabit its surface, and enjoy an existence, which is productive of as much hap]^ess to them, as ours is to us. It may be very properly asked— if the moon is not a habitable body, for what purpose was it created? This is a question wlUch is more easily asked than answered. We might as well ask, why the greater portion of the surface of the earth is not land instead oi water? wlqr is Africa a sandy desert, or why are the polar regions tmfltted for the hiftbitation of man? A«oording to geologists, the £arfJI^ was, for a long' period of time, in a state unfit for animal life, and that it has unclenrajiie many successive changes, extending through a long p«ri6d Of ttnie, htkata it ma fitted for the abode of maflokind. It may be th«l> the moon is in a transitioa sti^te, and h|« not arrived at a state i^it- alie for aziimal life. jjaaDmnaxT' or sMsrn^s . /W* Jafow bvlfew tff ih6 nuaMtoiw pnipoidi fh« moon mo^ serifr, in the eoonomy'of ntttare. We do mow that it ezegtfi * poiferfnl ittfliMnoto in nosing tlie tufes. Its mild betahf tend to ditpel the gtDom of night; eapedallyin the dreary winter of the pelar regions. It famishes the n«vigal6rs ftiseii, the teost certain means known, of determining their longitude. In the ealrliest periods of the world, its changes famished tho aneimts with a oonyenient mode of ^reckoning time. It Sh iiad thought by numy to exert an important inflnenetf upon the aiiimal and yegetable kingdom; but this is denied l^ otheirs d^toftUj entitled to orediti ■• ax •"v;'j LESSON XXXT^ .' BCLIP8E8. QuBSTiOM. What is an eclipse ? Ak^Wik. It is the interception of the sUn'd tays by :iOBi6 opaque body. P*> fipw ariB eclipses divided, with respect to tlie body eohpsed ? A. Into two kinds ; solar and lunar. 9* What is' a'solar eclipse 1^ A^It is an'edipse of the sun. Q. What is the cause of an eclipse of the sun ? Aurit is caused by the moon's passing between the ejftt^ih aiid son; and cafiting its shadow upon th6 QV^ W!heh mcfet au edHpiS of th^ilti^ Au It caiilM^>peh only felt iiew moon, Ai'^tt 11^ an eclipse of 'the mooni' Qy Tffhai Ofinses an eolifme of the moon ? A^l^iflf'etttuffid by the inoon's passing throttgh the A. It can happen only at full moon. • POWerfnl dttpelthe I known, 9f the world, ^t mode of important bat thicf is ECLIPSES «cC\ tin's tKy% 3 tlie body ween tHe pon thfe tirgfhthe f <^(|^i>S^. «,./#:fl[^|«t'!»'* -, -ff* .. 'v . <>*ti4i^ffii^0f:m '\ tl^yt^iMMiywti \ ILLUBTKATID ABTROIKMIT. &h Of Hew ara -^dipiM ^iricUdr with retp«dt to ib* ftmoimt eelipiMd? A. Into total and pitrtial. Q. What is ft total eclipse? A. It id an eclipse of the whole of the sun or moon. Q. What is a parti'J eclipse? A. It is an edips'e of bnly a paH bf the siin or moon. Q. Wbatisan'ailniilaaredlipse? A, It is an eclipse of the central part of the sun, when the moon is so far from the earth^/thaithe sun can he seen' like a hright ring around it. Q. Do we have f» edipse of the Sim at eVor;^ iiefWEdoon? i* A. We do not Q. Why do we not have an edipse^ 6t the siixi at ei^ iiew" moon? A; Because at new moon, the^ moon is generally too high, or too low, for its shadow tiO fall upon the- earthi Q. Do we have an eclipse of the moozi %t -evtey fo&'mdbh ? > A. We do not; at full moon^thembon geni^raUy panes above or below the earths shadow. Q. "Wyft'i^th^ lemgth of the earth's diadow? A. About 600,000 miles. [NotB.^This' u^ the mean or average length.] A.^ Abottt-SHOOO miles. [NdTB;--^a%[is is ^e mean, or average length.] Q.^^«WiiSfcfe^a^«(i»f'^ A It is the twelfth part of the ap^^SO^t 'diame^r of tiwrnm^oi^^iidoiEi^s^se. Q. ; -^iiirifi^tbeflgt^lktblrt iiiiiht)^ df ec%l^mman tale pUMefakft-yeitff A* Beven ; five of the 3un> and two of the modn. 5^ •ABRIDaiCiSNT OF BIOTH'S Q. Wuki is the leMt number of eeliptes ih«t oMi take place in a year ? A. Two: and both must be of the sun. LESSON XXXIV. THE MOON'S NODBB, * QuBSTZOK. What are nodes? Answer. They are two opposite points, where the orbit of the moon, or any other planet, intersects the plane of the earth's orbit, or e^iptic Q. What angle does the moon's orbit make with the plane of ^e earth's orbit, or ecliptic. A. About 61 degrees. (S** 8' 48*.) ,Q. Wh*t pajrt of the moon's orbit is aboye, or north of theij^lane of ih^ earth's orbit ? A. One-half; the other half being below, or south, of the earth's orbit. Q. What is the ascending node ? A. It is that point, where the moon passes the phine of the earth's orbit from south to north. Q. What is the descending node? A. It is that point, where the moon passes the- plane of the eartn's orbit from north to south. Q. Do the nodes change their position, as regaords a filed point in the heavens ? A. They have a retrograde motion of about 19 degrees in a year. Q. WhenisthemooninnorthlatitAdei&theheaffens? A. When it is nprth of the earth's orbit^oreoliptV}. Q. When is the moon in south latitude in the heateib ? .A. :l^en it is«outh of the eo^'s orbit, or ecliptic. kt 0A& take ^-,V have the the sun >n» besides V centres, be«arth. the water gnivity^ jrth?: B of the lea to H. le earth ? B '*eriHlKin. r Wfipt to '^ Fayes? r ^!*i ^^.-i'. .■-*_:^"-.'*'"»ri^e^'w»'r''' r- • »*■,»-■■■ ILLUSTRATED JLSTROKOmr. B5 m. A. It causes these elevations, or tide waves/ to pass from east to west around the earth. Q. What is tide? A. It is the rising and falling of the waters of 1^ ocean. Q. How are the tides divided, with respect to the rising and fieJling of the water ? A. Into flood and ebb. Q. What is flood tide ? A It is the rising of the water. Q. What term designates the greatest elevation of thW flood tide? A. High water. Q. What is ebb tide ? A It is the falling of the water. Q. How often do flood and ebb tide ooooif ? A Twice in about 25 hours. Q. Do the tides rise at the same hour every day? A. 'xheyTise about an hour later each day. Q. Why do the tides rise later ? A. Because the moon passes the meridian atsoui an hour lifter each day. Q. What Q. i Hoitr wide is the sodiac ? A. Sixteen degrees wide; eight degrees m a straight line. Q. What is astronomical refraction? A. It is the deviation of the rays of light in their passage through the atmosphere. Q. What is the cause of this refraction ? A. It is caused by the increase of the density of the atmosphere towards the earth. n62 AHRIDOMElfT or SMITH'S t . r Q. In what part of the heavens is the light of a body most \ refracted f A. In the horizon. Q. "What effect does this refraction have npon the son, at! its rising and setting? A. It makes the sun appear above the hoi*izon,l when it is actually below it. Q. Does this affect the length of the day ? A. It makes the day from six to ten minutes -longer, from sunrise to sunset. ..Q. Is the light of a body refracted when it is in the zenith ? A. It is not. . Q. WhatistwiUght? A. It is that faint light, seen before the sun rises and after it sets. Q. "What is the oanse of twilight ? A. It is caused by the atmosphere's reflecting the light of the sun. Q. Twilight ceases when the son is, how £ur below the hbiision? A. Eighteen degrees. LESSON XLII. P4B4LLAX, , Qux0T;ov. O^IThat is parallax ? Answer. - it iel the difference between the ppparont and true place of a heavenly body. rjQ,, -V^hat; is the apparent place of a planet ? A. It is the place where it appears to be,;iit)>0B seen from th^ siuface of the earth. . Q. l^t is the, trae place of a planet ? A. It is the plfice whei^e it would appear tQ hi^i^ body most < A' rii'\ i A }( \ l.I.AV I pheson, at! honzon, minutes le zenith? sun rises •cting the below the ^,fP'^^ kppai^ont %mhdn ■■A- ^HH ULUSTBATED ASTflONOMY. 63 see!i from the centre of the earth, or cecire of motion. Q. Where is the parallax of a heavenly body the greatest ? A. At the horizon, and decreases to the zenith. Q. How are parallaxes divided ? A. They are divided into two kinds; diurnal and annual parallax. Q. What is diurnal parallax ? A. It is the apparent difference in Uie situation of a heavenly body, when seen in the zenith and hori- zon of two places, at the same time. (See parallax of Mars ana Moon.) Q. What is annnal parallax ? A. It is the apparent difference in the situation of a star, as seen from the earth in opposite points of its orbit. Q. Have the stars been observed to have any sensible parallax? A. A' few have been observed to have a small parallax of a part of a second. (NoTH^-^No parallax has been discovered in more than 80 or 40 of them.) Q. What is tiie cause of their having no appreciable paraUftx? A. Because they are at such an immense distaiice fix>mus. Q. If the earth's orbit were a soUd ring, ho^ large Would it appear when viewed from the nearest fixed star ? A. No laigert'l^an^ a lady's, finger ring. LESSON XLIII. ZJ0mT AND HEAT' QUB^VXCN. W|i»t bodies produce I%ht? Answer. Luin|];ip\iLB bodief9« 64 ABRIDGMENT OF SMITE^S Q. Is light a substance thrown off from a luminous bodyj or is it caused by a vibratory motion ? A. lb is probably caused by the undulations of anj extremely subtle fluid. Q. In what direction are the rays of light thrown off from^ a luminous body ? A. In straight lines, and in all directions. Q. With what velocity does light move ? A. About 192,000 miles a second; (192,500.) Q. How is this amazing velocity ascertained ? A. By observing the eclipses of Jupiter's moons. Q. In what proportion do the light and heat of the planets increase or decrease ? A. In inverse proportion to the squares of their distances from the sun, Q. Which planet has the most light and heat, and which the least ? A. Mercury has the most, and Leverrier the least. Q. If a board a foot square be placed one foot from a lighted CMidLe, how many feet square would the shadow be upon the waU, nine feet from the candle ? A. Nine feet square, or eighty-one square feet. Q. What amount of light and heat would fall upon the one foot and upon the 81 feet ? A. The same amount of light and heat would faU. upon each. LESSON XLIV. TSBBBaTBIAL AND CELESTIAL GLOBES, QuKSTiOH. What is a globe ? Answbb. a globe is a round body or sphere. Q. How many kinds of globes are there used in Astrotiomy ? A, Two; terrestrial and celestial globes, [inouB bodyj Dions of an| \ym off troial s. boo.) s moons, the planets s of their and whioh the least. oot from a shadow be € feet. 11 npon the ronld faD BBS, 5re. roiiomy? X\.^ ( KLKsr dk^ ' • ».v< ■■". Q. Wl A. It Q. Wl ? A. Co rivers, r( Q. W] A. It Q. W A. Tl way, an from wl Q. W A. It name oJ Q. 'Vi A. I^ Q. Ii sappo8e< A. C Q. I gappose A. I (Inside Q. ^ A. I in the Q. ( A. ] us, an to app Q. ' A. ] the wi ILLUSTRATED ASTKONOMY. 65 '^'^:'^- Q. What does the terrestrial globe represent? A. It represents the earth. Q. What %re drawn upon the surface of the terrestrial {^obe? A. Continents, islands, mountains, oceans, seas, rivers, republics, kiugdoms, empires, etc. Q. What does the celestial globe represent ? A. It represents the heavens as seenfrom the earth. Q. What are usually drawn on the celestial globe? A. The constellations of stars, galaxy or milky way, and the figures of various animals and object from which the constellations are named. Q. What is a constellation ?i A. It is a group of stars, to which is applied the name of some animal or object. Q. What is the number of constellations ? A. Ninety-three. Q. In viewinR the terrcGkial globe, where is the observer supposed to be placed ? A. On its surface. Q. In viewing the celestial globe, where must the observer suppose himself to be placed ? A. In the centre, looking towards the heavens. (Inside, looking out.) Q. What is the gala:icy or milky way ? A. It is a luminous belt forming a complete circle in the heavens. Q. Of what is the galaxy or milky way ooniposed? A. It is a vast number of stars, so far distant from us, and situated so nearly in the same direction, as to appear like a thin cloud. Q. What is the position of the milky wi^ in tiie heavens ? A. It extends from nortiieast to southwest through the whole circumference of the heavens. 1, .■* I .' 1 66 ABRIDGMENT OP sMlTH*^ Q. What are the celestial poles» or poles of the heavens? A. They are tlie^ poiiits where the eai-th's axis, if exxefided, ^otild meet the heavens. .J \. LESSON XLV. QussTioN. What does the plane of the equator form, wllen extended to the heavens ? Answer. The equinoctial, or celestial equatof . ] Q. At what angle do the eoliptio and equinoctial iiiierseot each other ? A. At an angle of 23 J degrees. (23" 28'.7 Q. What does the plane of a meridian form, wh«li extended to the heavens ? A. A celestial meridian, or circle of declination. Q. What aie measured on celestial meridians ? A. Declination and polar distance. Q. What is the decUnaf io a of fk heaveaty hody ? A. It is its distance Irom the eqilinoctial, north or south. Q. To what are the declination and polar distance always equal ? A. They are equal to 90^dcgrees, or a quarter of a circle. Q. What is the right ascension of a heavenly body? A. It is its distance ^ast of the first point of Aries, measured on the equhioctial. [Q. What angle exprMses the right ageinaion? A. The angle between the meridian passing through th« body, and the one pasiing through the first point of Ari^s.] Q. ISm fiftrli jdi^t ajswenndn reckoned ? A. 360 degi'ees/or quite round the heavens. ilLUSTtlATEb ASTBONOMY. if m heayens? 's axis, if irm, vrhon mtol^. ] 1 iafterseot Of li extended ination. I north or we always uarter of »ody? of Aries, roughthe Aries.] IS. Q. What are circles of latitude on the celestial globb ^ ' A. They are great circles which pass through the poles of the ecliptic, and cut its plane at right angles; Q. What is the latitude of a heavenly body ? A. It is its distance north or south of th^ ecliptid^ measured on a circle of celestial latitude; Q. What is the longitude of a heavenly body? A. It is its distance east of the first point of Ariefe^ measured on the ecliptic. ijg [Q. What angle ezpresses the longitude ? A. The angle between the circle of latitude parsing through the body, and the one passitig through the first ^oint of Aries. Q. Where is this angle formed ? A. At the poles of the ecliptic, where the circles of lati- tude intersect one another.] Q. How far is celestial longitude reckoned ? A. It is reckoned 360 degrees. LESSON XLVI. QuESTioK. What is a vertical circle ? Answeb. It is a great circle in the heavens, passing through the zenith and nadir, &nd cutting the hori- zon at ri^t angles. Q. What vertical circle is the meridian? A. It is that vertical circle which passes through the north and south points of the horizon. < ■■ >j Q. Which is the prime vertical? A The vertical circle which passes through the east and west points of the horiaon. Q. What src iv^oasured od die v j'fcioal circles? A. Altitiidi id zeiilth distance. fm 68 ABRIDOMENT OF SMITH S Q. What is the zenith distance of a heavenly body ? A. It is its distance from the zenith. Q. To what are the altitude and zenith distance always equal? A. They are equal to 90 degrees. Q. What is the azimuth of a heavenly body ? A. It is its distance east or west of the meridian. [Q. What angle ezpMSMS the admath ? IIL The angle between the meridian and the vertical circle pnRng through the body. ,Q. What is the ampUtude of a heavenly body ? A. It is its distance north or south of the prime vertical. Q. What angle exprefl|B« the amplitade. A. The angle between the prime vertical, and the vertical circle passing through the body. Q. Where are the angles expressing asimnth and amplitade formed. A. At the zenith where the vertical circles intersect each other. - Q. On wtet oirole are these an|(lef measured ? A. On the horizon. Q. To w'l lat are asimnth and amplitade always eqaal ? A. They are equal to 90 degrees.] [The diagram can be used to iHustrafee azimuth, amplitade, altitude, and zenith distance, by supposing the eoUptic to re- present the celestitd horizon, and tiie circles of celestial lati- tude to B^resent vertical oiroles.] LESSON XLVII. THB FIXED 8TAB8, QusanoN. What «.re those stars called which always ap« pear to be in ^e same situation with respect to each otbier ? Answir. They ar^ called the fixed stars. Q. What are the fixed stars supposed to be ? A. They are supposed to be suns like our own^ with planets reyohnng around them. ILLUSTRATED ASTRONOMY. 69 ice always oeridiaD. tioal circle e vertical. be vertical ndflfonned. >neot each amplitude, iptic to re- estial lati. vi^ajs ap- iTown^ Q. Are the stars laminons or opaque bodies ? A. They are luminous bodies. (Astronomers have no doubt on this point.) Q. Are all the stars of the same magnitude* as the sun ? A. They are not ; some are larger, and others no doubt smaller than the sun. [AstronOmerB, until recently, considered all the stars to he ot about the same magnitude, and probably as large as the sun; and that the stars of the first magnitude owed their brilliancy to their being nearer to us ; but it has been^Mnd that the brightest star (Sirivs) in the whole heaven^'Knd which was oonsidered to be the nearest fixed star, is at a much Sreater distance than some of the smaller stars. This clearly emonstrates that they are of very unequal magnitude.] Q. What is the distance of the nearest fixed star, a (Alpha) Centauri? A. It is so far distant that a cannon ball going 500 miles an hour, would take four millions of years to reach it. Q. What is the number of stars whose distance is imper- l(Boti(y known to us ? A. About 35 ; seven of which have their distances . determined with considerable certainty. Q. Do all the stars remain of the same brilliancy ? A. They do not ; some exhibit a periodical Qhange in their light. Q. What is supposed to he libe oause of this change in their light? A. The revolution on their axes is supposed to present alternately to us, sides of different bright- HesBk Q. What are those stars called, which appear to be sur- voiind«d hj a tiaa ataaosphere ? A Nebuloas stars. Qk Do itan ever ^ieappear, or new ones beoome IMe? ^^ f 70 ABRIDGMENT OF SMITH'S •1 A. Thirteen stars have disappeared, and ten new ones become visible, during the ia»t century. [There are now ieven or eight well-attested oases of fixed stars euddsnly glowing for a time with such hrillianoy as to be visible in the day time, through the intensity of their light; ( then gradually fading away, and becoming entirely extinct. LAP1.A0K fliixiks that some great conflagrations, produced by extraordinary causes, have ti^n place on their surface. »■ Q. What is supposed to b« the cause of their disappear- ance ? "H^ They have probably ceased to be luminous. Q. How do astronomers acooant for the appearance of new Btara ? A. Opaque bodies may have become luminous, or new suns may hava been created. LESSON XLVIII. QuBSTiOM. What do the* milky way and the single stars that are visible to the naked eye, including our sun, ooa- «titute? Answer They! constitute an immense cluster, or firmament, entirely distinct from the other clusters or nebulae of the heavens. Q. SVhat is the shape of this great cluster cr firmament f A. It has the form of a wheel or burning-glass. [The stars extend much farther in the direotioh of the plane of the milky way, than they do at right wgles to it. ^ SU DUCHIAM ;] ,'>;hf!rv; • ■:l'i' .A 4); Wlwt ii.the number pf stars in our clostepr ? . or/riif A. They have been variously estimated, from 10 to 100 Dxiilw^s.^,-^f ,, Q. By wliat term do some astrononiers ^ate dtilr doster or firmament? .i-rlaat .>'.. [The term universe, was until recently, used to denote iHiib whole creation of Gon, and wm never used in the plural num* minous. )pearanoa of nnament ? PHASES OF IH I: MOON IMAGE EVALUATION TEST TARGET (MT-3) // ^./ ^.^. -^ is i< .* ^t' .4^ ^Ak ^ % 1.0 1.1 lit m £ Itt 110 IL25 ■ 1.4 1^ FholDgraphic .Sciences Carporation as WBT MAM STRUT WMSraR,N.V. I4SS0 (71«)873-490S 4^ .* -SB.;- ILLUSTRATED ASTRONOMY. 71 "het't bat astronomers use the term to denote an immense ' 'Armament or olaster of stars, entirdy distinet from other idosters — of whioh there are many thousands yisible with the telescope — ^and are at an immense distance from each other. . Henee» in speaking of these oiusters, they eall them nniverses. — Pbow. Mitohblii.] Q. Do the fixed stars have any apparent motion ? A. They do, but it is so slight^ as not to be easily detected. • Q. Aronnd what, are all the stars in our cluster, including the sun, supposed to revolve ? A. Around the common centre of gravity of the cluster. Q. What group of stars is thought to be near the centre of the cluster? A The Pleiades, or seven stars.— (Db. Maedl^r.) Q. In what part of the cluster is the sclar system situated ? A. It is comparatively near the centre. Q. How far from us is the centre of the elufiter supposed tobe? A. About 150 times the distance of the nearest fixed star. [Light is about 8 minutes in 'coming from the sun ;. about 8j^ years in coming from the nearest fixed «tar, a CmitAuri ; abpnt 600 yean in coming jErom the sapposed centre of the duster ; and about 5,000 years in coming from the most re- mote stars in the cltu^er.] Q. How long will it take the sun to revolve around this centre of gravity? A. About twdve millions of years. Q. What other motion have some of the stars, betides around the centre of the cluster? A. Multiple stars, consisUi^g of two or mor0, rq-> volve likewise around their conpion centre of Q. Whal is. the number of these mj^i^lple stars ? A. About 6,000 have been observed ! 72 ABBIDOMENT OF SMITH'S Q. Do these stani ajvpear double to the naked eye ? A. ^Hiey^o not; the moat, require a good teloi- BCop& to separate them. Q. When miiltipie Stan conaiit of but two, what wre they nsiu^oaUed? A. Doable stars, or binaiy systems. LESSON XLIX. NBBULM, QuKBTXoir. What appearance has a nebula? Answer. A nebula Appears like a spot of pale light seen in the heavens. Q. Of what are the nebal» composed ? A. The, most of them are gr6at clusters of stars» so fax distant as to appear like a tiiin cloud. Q. Azetheremany of them?' A. About 6,000 have been discovered. INote. — ^Their nunber is probably much greater; perhi^ infinite.] Q. H^t is tibe distanoe of these nebnlsB ? A. Some of thein are said to be so fiir distant, that light, travelling 192 thousand miles a sedondi would not reajc^ us m less than 30 millions of years. — I^ROF. Mitchell.] Q. Are they Tisilitotp the nalced eye ? A Only a few are seen without a telescope. Q< How large dp they appear when viewed with a tele- ' A. Soine of them lippear as lu;ge as one-ten^ of the disc of the moon. . Q. A» thesvnlbiiiiB^Mi^iit all parti of the hear^ .ILLUSTRATED ASTRONOMY. 73 ley >ale are. ii«iw bat aid >le- of A. They are, although they ard more numerous in a narrow zone, circumscribing the heavens, at right angles to the mUky way. Qi» Into how many classes may nebnlflB l^e divided ? A. Into five classes ; viz., resolved nebulsB, resolv- able nebukB, stellar nebulsB, irresolvable and planet- ary nebulse. Q. What are resolved nebulsB ? A. They are those, which have been discovered with the telescope to be clusters of stars. Q. What are resolvable nebnlse ? A. They are those, which are considered to be composed of stars, but are so far distant that the telescopes have not as yet resolved them. Q. What are stellar nebulae ? A. They are those of an oval or round shape, in- 'Creasing in density towards the centre. {Note. — They sometimes present the appearance of havmg a cUm star in the centre.] Q. What are irresolvable nebnlte ? A. They are those, which are considered to be luminous mp^.ter in an atmospheric state, condensing into solid bodies like the sun and planets. Q. What are the planetary nebulae ? A. They are those, which resemble the disc of a planet, and are considered to be in an uncondensed ustate. Q. Are all nebuln beyond our cluster ? A. They are, except the milky way^ and nebulous .stars. Q. By what general term do astronomers designate each nebula or duster ? A They call each nebula a UNiYifRSE, or Firma- JIBNT. ^ ♦ 74.. ABBIDOMENT OF SMITH'S [Q. Whftt OMi you ny of th« grert nebula In fhe Oi»THovin>Br A. It rM^bles our cluster, or firmament of stars. Q. 'WhatoaayouMyoT fhofproatr'ibtdainOuoifr A. This nelrala was eonsidered to be ItuninoiiB matter in- ah nnoondensf d state ; but it has lately been discovei^d to be stars by Lord Bosse, with his powerful telescope. A''i»/A—-Thi8 nebula is yiaible to the naked eye. Q. ^'*f 1m tUo probable oanie of many of the nebulae appeaxlnff elllptioaloreloBiateat (Saa DzAoaAx.) A. It is probably caused by the edee of the nebola beinff tnmed more or less towards u£ ILLUSTRATED ASTRONOMY. m to ^'v i v.' «-ifV.'',-,» PROBLEMS P£BFOBUED WITH THE TEBBESTBIAL OLOBB. • Pboblsm I.— To find the Latitude of any given plaee, RuLi. — Bring the given place to the graduated side of the brass meridian, and the degree on the brass moridian over the place is the latitude, which is either north or south.' Q. What is the latitude of New York? A. About 41 degrees north. Q. What places have nolatitnde ? ^ A. All places on the equator. Q. Find the latitude of the following places : — London, ' Philadelphia, Boston, Washington, Edhiburgh, Borne, Dublin, Amsterdiam, Moscow, Stockholm, Quito, Vrxioo, Algiers, Astoria, Gape of Good Hope, Hb,luax, Norfolk, Aleppo, Athens, Isi>ahan, Madrad, Madrid, Gape Horn, Gairo, Ftague, Dantzic, TenAriffe, Lisbon, Tripoli, Paris, Lima, Vienna. Pboblkm 2. — To find the Longitude of any given place. Bulb.— Bring the given place to the brass meridian, and the degrm on the equator under the brass meridian, is the longitude. [I^ote. —Longitude is reckoned from the meridian of Qxecn- wioh, 180 degrees east and west.] Q4 What is the longitude of New York? A 7^ <^<'ees west. Q. What is the longitude of Pekin? A 116 degrees east. Q. Find the longitude of the following places : — Washington,Hartford, ■ SandwichlslandSyGibraltar, Quebec, Rhodes, ■ Calcutta. Gonstantinople Ganton, Havana, Jerusalem, Nankin, Pekin, St.Petersburgh,yenice,. Bexlin, Astoria, Gape Horn, New Orleans, Bio JaneirOi fi ABRIDGMENT OF SMITH'S PiOBLBM 8-.^— To find way plaet whoM laHtiMl§ and longitude ar§ given, BuLS. — Bring the giveii longitude to the brass meridiAn, and nxldeir the glvien latitnde is the plaoe required. Q. What plaoe is sitnated in seventy-four degrees west longiWde, and forty- one north latitude ? A. New York. Q. What places have the following latitudes and longi- tildes? ^ Lat. 42® north, Lon. 71 ^ west. Lat.84® south, Lon. 18® east. Lat. 58® north, Lon. 6® west. Lat<41® north, Lon. 72® west. Lat. 88® north, Lon. 9® west. Lat.89® north, Lon. 75® west. Lat. 46® north, Lon. 75® west. Lat.82® north, Lon.81®west. Pboblkm 4. — To And all tho$e placet that are in (he tame latitude or longitiiae al a given ptaee, . BlTLa. — Bring the given point to the brass meridian; then all the plaees under the meridiim have the same longitude ; turn the globe round, Imd all places whi 61' . 10*» 4'N. 8s 17« 21' 22 62 N. 2 18 67 21 6 S. 11 66 6 29 S. 2 6 63 12 3 8. 1 11 26 44 20 N. 7 9 22 27 N. ^ 4 26* 67 Pboblbm 6. — The latitude of a pla^e, tTte day and how being given to place the Olobe in aueh a manner aa to repre- aent the heavena at that time in order to point out the a-ituO' tiona of the conatellationa and remarhable atara, BuxiB. — ^Elevate the pole for the latitude of the place, and set the f^obe due north ana south by a meridian line; find the sun's Slaee in the eoliptie, bring it to the brass meridian, and set the in- ex^o 12. If tne time be afternoon, turn the i^obe westward; if in the forenoon, turn Uie globe eastward, till the index points to the j^ven hour. The surface of the globe then represents the ^rpearanee of the heavens at that time and place. 82 smith's illustrated astronomt. Pboblsx 6. — To find the ditianoe of the Stan from each other, im degrees* Bvia. — Jatj ihe qoAdnnt of altitude 0T«r any two itanr, so that the divisiott marked xnaar be on one of the stars; the degrees between them will show their distance, or the ar jle which these Btars subtend, as seen from th6 larth. EzAMPLV. — ^What is the distanee, in degrees, between the two starsi Veg* and Altair ? A. 34 degrees. Also, between BegnlnS and Prooyon, " '* Aldebaran and Sirins, ** ** Arctnms and Spioa, M'f ! " ' Oftpella and the North Star ? ■..>mmtmr each >that igrees tiiese 1 the