,transcriber's ,notes3 ,underscores 80 before and after a word or phrase indicate italics in the original text4 ,equal signs 80 before and after a word or phrase indicate bold in the original text4 ,small capitals have been converted to ,,solid capitals4 ,illustrations have been moved so they do not break up paragraphs4 ,typographical and punctuation errors have been silently corrected4 ,,the ,,book ,,of ,,stars ,by ,a4 ,frederick ,collins ,the ,book of ,wireless ,the ,book of ,stars ,the ,book of ,magic ,the ,book of ,electricity ,gas1 ,gasoline and ,oil ,engines ,the ,amateur ,chemist ,the ,amateur ,mechanic ,how to ,fly ,the ,home ,handy ,book ,keeping ,up with ,your ,motor ,car ,motor ,car ,starting and ,lighting ,d4 ,,appleton ,,and ,,company ,publishers ,new ,york ,,the ,,book ,,of ,,stars ,,being ,a ,,simple ,,explanation ,,of ,,the ,,stars ,,and ,,their ,,uses ,,to ,,boy ,,life ,,written ,,to ,,conform ,,to ,,the ,,tests ,,of ,,the ,,boy ,,scouts ,,by ,a4 ,,frederick ,,collins 8,,the ,,book ,,of ,,wireless02 8,,the ,,book ,,of ,,magic10 ,,etc4 ,illustration ,,fully ,,illustrated ,d4 ,,appleton ,,and ,,company ,,new ,,york ,,london #aibj ,,copyright1 #aiae1 #aibj1 ,,by ,d4 ,,appleton ,,and ,,company ,printed in the ,united ,states of ,america ,,to ,,the ,,burnhams ,,with ,,pleasant ,,memories ,,of ,,mount ,,hamilton ,,nights ,a ,,word ,,to ,,you ,the stars are the friends of everyone who knows them4 ,if you have never stood out in the open and watched the stars on a clear night1 you have missed the most wonderful sight to be seen from this little old mud ball of ours1 and my advice to you is not to let another night go by without making friends with the stars4 ,by the stars ,i mean everything in the far off sky that we can see1 and this includes the white hot points of light we call the fixed stars1 the blazing sun1 the bright planets1 the pale1 cold moon1 the fiery comets and the burning meteors4 ,all of these things in the sky are so easily ours to look at1 to enjoy and to use1 that we are apt not to take them at their true value1 just as many of us do not appreciate to the fullest the green grass1 the trees1 the birds and all the other good things we have without price4 ,you may wonder how you can make any use of the stars1 but there are dozens of ways by which they will serve your purpose1 from finding the north to lighting a fire1 and from telling the time to sending a signal1 and they are all easy to you when you know how4 ,all the apparatus you need so that you can know the stars is a pair of good1 sharp eyes1 and if you are fitted with these you are ready to begin your work in starcraft this very night4 ,a great many folks believe that they must have a telescope with which to see the stars1 and while1 of course1 a great deal more can be seen with a telescope than without one1 still it must be remembered that the telescope was invented not longer than four hundred years ago and that many important discoveries in astronomy were made long before the telescope was invented4 ,and1 by the way1 it was a boy who invented the telescope4 ,a small telescope1 or a pair of field or opera glasses1 will show you many things in the sky which you cannot see with the naked eye1 and if you have one of these instruments1 by all means use it4 ,on the other hand1 you can get along very well without a glass of any kind until you have learned the things that are set down in this book4 ,to win a merit badge in the organization of ,boy ,scouts1 a boy must pass certain tests2 but it is just as necessary for you to know the stars as it is for a ,boy ,scout1 and this book is so written that anyone who studies it can pass the ,boy ,scout tests1 and there are a few other things in it which everyone should know4 ,once that you have an insight into starcraft1 you will never need to be told again how very interesting and useful the stars are1 and once that you have mastered the chief points in this book1 you should make or buy a telescope having a two-or three-inch objective and get a little closer to the stars4 ,if any questions should come up which you don't understand1 if you will write to me1 ,i will write to you4 ,a4 ,,frederick ,,collins4 8,,the ,,antlers10 ,congers1 ,n4 ,y4 ,,contents ,,chapter ,,page ,i4 ,,how ,,to ,,find ,,the ,,north ,,star #a ,,ii4 ,,how ,,to ,,know ,,the ,,stars #ad ,,iii4 ,,the ,,sun1 ,,the ,,brightest ,,of ,,all ,,stars #bi ,,iv4 ,,the ,,planets1 ,,the ,,sun',s ,,kiddies #df ,v4 ,,mother ,,earth1 ,,old ,,adam',s ,,planet #ff ,,vi4 ,,the ,,moon1 ,,the ,,earth',s ,,daughter #hi ,,vii4 ,,other ,,things ,,in ,,the ,,sky #ajg ,,viii4 ,,seeing ,,the ,,stars #aba ,,ix4 ,,the ,,spyglass ,,or ,,telescope #acf ,x4 ,,the ,,time ,o' ,,day #aea ,,xi4 ,,the ,,stars ,,of ,,the ,,zodiac #aff ,,xii4 ,,valuable ,,information #ahe ,,appendices #aic ,,definitions ,,of ,,some ,,words ,,and ,,terms #bac ,,index #bba ,,list ,,of ,,illustrations ,,fig4 ,,page #a4--,starboard showing cleats #b #b4--;,cardboard star #b #c4--,the ,north ,star and ,big ,dipper on starboard #c #d4--;,finding the ,north ,star and the ,big ,dipper #d #e4--,line for sighting the ,north ,star #e #f4--,the ,big ,dipper as we see it #f #g4--,the ,great ,bear as the ancients saw it #f #h4--,the ,earth1 ,pole ,star and ,dog ,star #g #i4--,the ,north ,star and ,big ,dipper in winter #i #aj4--,the ,north ,star and ,big ,dipper in spring #aj #aa4--,the ,north ,star and ,big ,dipper in summer #aa #ab4--,telling time by the ,big ,dipper #ab #ac4--;,constellation of ,cassiopeia #ae #ad4--;,cassiopeia as the ,arabs saw her #af #ae4--,the ,little ,dipper or ,little ,bear #af #af4--,the ,little ,dipper made into a ,little ,bear #ag #ag4--,the ,great ,square of ,pegasus #ah #ah4--;,holding the chart of ,pegasus overhead #ai #ai4--,the ,flying ,horse of ,pegasus #bj #bj4--;,figure of a trapezium #bj #ba4--;,constellation of ,orion #ba #bb4--,orion the ,mighty ,hunter #bb #bc4--;,constellation of ,auriga #bc #bd4--;,auriga the ,shepherd #bd #be4--;,constellation of ,taurus #be #bf4--,taurus the ,bull #bf #bg4--,star map showing a part of the sky #bg #bh4--,smoking glasses over candle flame #bi #bi4--,seeing the sun through smoked glasses #cj #cj4--;,a candle flame showing layers of flame #ca #ca4--,the sun as seen with a field glass #cb #cb4--,prominences of the sun compared with the size of the earth #cc #cc4--;,cross section of the sun #cd #cd4--,sun spot in ,photosphere #ce #ce4--;,barometer tube #cf #cf4--;,barometer complete #cf #cg4--;,boy focussing burning glass on leaves to make fire #ch #ch4--;,boy sending flash signal with mirror #ci #ci4--;,continental ,morse ,code #ci #dj4--;,base for heliograph #dj #da4--;,back view of heliograph #dj #db4--,top view of heliograph #da #dc4--,side view of heliograph #da #dd4--;,heliograph complete #db #de4--,numbered strip for sundial #dc #df4--,tin ring for sundial #dc #dg4--;,brass semi-circle with shadow wire #dd #dh4--,sundial complete #dd #di4--,to find the ,north by a watch #de #ej4--;,a star and a planet in a telescope #df #ea4--,sizes of planets compared #dh #eb4--,three views of ,mercury #di #ec4--,mars as seen through a telescope #di #ed4--,three views of ,venus #ej #ee4--,the earth #ea #ef4--;,jupiter #ea #eg4--,saturn #eb #eh4--,uranus #ec #ei4--,neptune #ec #fj4--,marbles on top of table #ed #fa4--,top view of solar system #ee #fb4--,solar system in perspective #ef #fc4--;,egg shell on plate #eg #fd4--;,boy throwing stone to illustrate centrifugal force #eh #fe4--;,iron ball pendulum swinging in a plane #ei #ff4--;,iron ball pendulum swinging in curved line #fj #fg4--,map of stars on sun's path #fb #fh4--;,diagram of position of constellations #fc #fi4--,plotting position of planet #fd #gj4--;,cross section of the earth #fg #ga4--,sails of ship can be seen after hull has disappeared #fg #gb4--,sailing round the earth #fh #gc4--,the earth moves under the swinging pendulum #fi #gd4--;,if the earth's equator were in a line with the sun #gj #ge4--,the earth tilted on its axis #gj #gf4--,light in room to represent sun #ga #gg4--,top spinning on plate #gb #gh4--;,circle around candle marked with seasons #gc #gi4--;,apple to represent earth suspended in air #gd #hj4--,position of the earth and sun in autumn #gd #ha4--,position of the earth and sun in winter #gd #hb4--,position of the earth and sun in spring #gd #hc4--,position of the earth and sun in summer #ge #hd4--;,cycle of seasons #ge #he4--,lines of force through and around a magnet #gf #hf4--,lines of force around the earth #gg #hg4--,watch spring needle for compass #gg #hh4--;,compass complete #gg #hi4--,pocket watch-case compass #gh #ij4--;,dial of mariners' compass #gh #ia4--,needle for dipping needle #hj #ib4--;,dipping needle complete #hj #ic4--,protractor showing degrees #ha #id4--;,earth surface divided into degrees #ha #ie4--,protractor set by dipping needle showing latitude #hb #if4--,two sticks screwed together #hc #ig4--,two sticks across bucket of water #hc #ih4--,protractor and sticks on drawing paper #hd #ii4--,sextant in use4 ,shooting the sun #he #ajj4--,shadows at the ,north ,pole #hg #aja4--,moon and earth joined together like a dumbbell #hi #ajb4--;,balls connected with an elastic #ij #ajc4--,map showing ,pacific ,ocean #ij #ajd4--;,imitating the volcanoes in the moon #ia #aje4--,real volcanoes #ib #ajf4--,naked eye drawing of full moon #ic #ajg4--;,experiment showing how one revolution of the moon round the earth makes it turn once round its axis #id #ajh4--;,apple cut to show crescent #ie #aji4--;,diagram showing how the moon's phases are made #if #aaj4--;,diagram of the moon's phases as we see them #ig #aaa4--;,boy1 lamp and orange showing phases of moon #ii #aab4--;,attraction of the moon causes the tides #ajj #aac4--;,how spring tides are formed #aja #aad4--;,how spring tides are formed #aja #aae4--;,how neap tides are formed #ajb #aaf4--;,how neap tides are formed #ajc #aag4--,view of the earth from the moon #ajd #aah4--,telling time by the moon #aje #aai4--;,eclipse of the moon by the earth 7experiment7 #ajg #abj4--,moon eclipsed by the earth 7diagram7 #ajh #aba4--,the moon as seen when in partial eclipse #ajh #abb4--;,eclipse of the sun by the moon 7experiment7 #aji #abc4--,the sun eclipsed by the moon 7diagram7 #aji #abd4--,total eclipse of the sun1 showing path of the sun #aaj #abe4--,total eclipse of the sun1 from photo #aaa #abf4--;,annular eclipse of the sun #aaa #abg4--,partial eclipse of the sun #aaa #abh4--;,comet showing ,nucleus1 ,coma and tail #aac #abi4--;,an ellipse1 parabola and hyperbola #aac #acj4--;,head and tail of comet do not obey the same laws #aad #aca4--;,halley's comet1 from photo #aae #acb4--,meteorite of iron etched with acid #aaf #acc4--,the ,milky ,way #aag #acd4--;,different forms of nebul #aai #ace4--,ripples or waves on water #abd #acf4--,vibration of a bell #abe #acg4--,sound waves in the air set up by bell #abf #ach4--,waves in the ether #abg #aci4--;,forming an image with a lens #abh #adj4--,the human eye #abh #ada4--,light reflected by an apple #acb #adb4--,light reflected4 ,spoon in glass of water #acb #adc4--;,how light is reflected #acc #add4--,prism #acc #ade4--,prism forming a spectrum #acd #adf4--;,convex lens #acd #adg4--;,concave lens #ace #adh4--,lipperhey's boy discovers telescope #acg #adi4--;,disk of cardboard for pinhole telescope #ach #aej4--;,cross section of pinhole telescope #ach #aea4--,the telescope 7,galileo7 #aci #aeb4--,opera glasses #adj #aec4--,pasteboard mounting of lens #adj #aed4--,pasteboard lens mounting #ada #aee4--,opera glass telescope4 ,cross section #ada #aef4--,telescope4 ,cross section view #adb #aeg4--,magnifying power of telescope #adc #aeh4--;,full view of moon #ade #aei4--;,glass globe cracked #adf #afj4--,map of the moon #adg #afa4--,the moon girl #adg #afb4--;,diagram showing how to find solar noon #aec #afc4--;,circle divided into #cfj degrees and #bd hours #aeg #afd4--,the earth divided into #bd standard meridians #aeh #afe4--,standard time meridians in ,u4 ,s4 #aei #aff4--,standard time at different cities #afa #afg4--,ruled glass in transit instrument #afb #afh4--,the time ball #afd #afi4--,receiving time signals by wireless #afe #agj4--,the zodiac as invented by the ancients #afg #aga4--,the zodiac as we know it today #afg #agb4--;,constellations and signs of the zodiac #agj #agc4--;,cardboard zodiac #aga #agd4--;,constellations of zodiac in circle #agb #age4--;,constellations of ,aries the ,ram #agd #agf4--;,constellations of the ,lion and ,big ,dipper #agg #agg4--;,constellations of ,virgo the ,virgin #agi #agh4--,libra1 ,lion1 ,scorpio1 ,virgo #agi #agi4--,lyra1 ,aquila1 ,capricornus #aha #ahj4--;,camera pointing to ,north ,star #ahf #aha4--,star trails #ahg #ahb4--;,boy looking through prism at slit in cardboard #ahi #ahc4--;,fraunhofer's lines #aij #ahd4--,the spectroscope #aia #ahe4--;,geometrical figures #aie #ahf4--,kullmer star finder #bji ,,the ,,book ,,of ,,the ,,stars ,,chapter ,i ,,how ,,to ,,find ,,the ,,north ,,star ,if you want to know something about the stars which will be helpful as well as entertaining1 the first thing you should do is to be able to find the ,north ,star4 ,the ,north ,star is taken as a starting point in the sky for two very good reasons3 first1 of all the thousands of stars which the eye can see1 it moves the least2 and second1 it is north from any place on the ,earth's surface from which it can be seen4 ,it must be plain then that this star is the most important one of all to us1 for by its friendly light we can easily tell the points of the compass1 though we may be lost in an unknown land or shipwrecked on a strange sea4 ,that is1 of course1 we can easily find the points of the compass if we have first learned how to find the ,north ,star4 ,how to ,make a ,star ,finder4--,to find the ,north ,star for the first time is a very easy matter if the simple directions given below for making and using a star chart1 or star finder1 are followed4 ,get a smooth pine board1 about #af inches wide1 #bj inches long and inch thick2 make two cleats of wood1 each of which is #a inch wide1 #ab inches long and inch thick1 and screw these to the board near the ends and on the same side1 to prevent the board from warping1 as shown in ,fig4 #a4 ,if a drawing board of any size is at hand1 it will serve the purpose just as well as a homemade board4 ,the next thing to do is to obtain a sheet of cardboard about #ab by #af inches and cover one side of it with a dull black paint2 when the paint is thoroughly dry lay it1 black side up1 on the smooth side of the board4 ,illustration3 ,,fig4 #a4--,,starboard ,,showing ,,cleats4 ,from another sheet of white cardboard cut out seven stars1 about the size and shape shown in ,fig4 #b1 and cut out another star nearly twice as large1 to represent the ,north ,star4 ,now place the white stars on the black surface of the cardboard in the positions shown in ,fig4 #c1 using the smaller stars to form the outline of the ,big ,dipper and the large star for the ,north ,star4 ,illustration3 ,,fig4 #b4--;,,cardboard ,,star4 ,when all of the stars have been properly arranged1 fasten them to the black cardboard with a bit of glue or mucilage4 ,push a thumb tack1 or a pin1 through the center of the large star1 which is the ,north ,star1 and well into the board1 so that the chart1 or star map1 can be turned round on the board with the ,north ,star as its axis4 ,when this is done your star finder is complete4 ,finding the ,north ,star4--,all being in readiness1 take this chart1 or star finder1 out-of-doors some evening when the seeing is good and all the stars in the northern sky are shining brightly1 and face about north1 holding the starboard in front of you1 as shown in ,fig4 #d4 ,usually the direction of north is well known1 and yet there are some places where the streets and roads do not run due north and south1 and for this reason it is sometimes hard to tell exactly which way is north4 ,in such a place either use a compass to get your bearing1 or1 if you haven't a compass1 face about as nearly north as you know how4 ,illustration3 ,,fig4 #c4--,,the ,,north ,,star ,,and ,,big ,,dipper ,,on ,,starboard4 7,position of ,big ,dipper in ,autumn47 ,having looked at your star chart carefully raise your eyes from the board until they are in a line with the northern horizon1 that is1 the line where the earth and the sky seem to meet4 ,keep on raising your eyes in a straight line until they reach a group of stars1 which is about #dj degrees above the horizon4 7,see ,fig4 #ih47 ,the line for sighting the ,north ,star is shown in ,fig4 #e4 ,all the stars of this group are very faint except one and this particular star will stand out bright1 distinct and alone1 for the other two stars of the same group which can be plainly seen are not very close to it4 ,the star you have found is the ,north ,star1 or ,pole ,star1 or to give it its proper name ,polaris 7pronounced ,po-la-ris74 ,illustration3 ,,fig4 #d4--;,,finding ,,the ,,north ,,star ,,and ,,the ,,big ,,dipper4 ,to make sure you have not mistaken some other star for the ,north ,star it will be a good idea to prove your find4 ,search around in the northern sky a little and you will see a group of seven bright stars fixed in the sky just as the cardboard stars are fixed on the black surface of your chart1 and which are shown in ,figs4 #d and #e4 ,the ,big ,dipper4--,this group of seven stars is called the ,big ,dipper because if a broken line joined all the stars together a very good figure of a big dipper would be formed4 ,a group of stars is called a constellation1 and this constellation is shown as we see it in ,fig4 #f1 and as the ancient shepherds and sailors pictured it in ,fig4 #g4 ,illustration3 ,,fig4 #e4--,,line ,,for ,,sighting ,,the ,,north ,,star4 ,in ,england this group of stars1 or constellation1 is sometimes called the ,plough1 for our friends across the pond see in it the likeness of a plough as well as of a dipper4 ,it is also called the ,great ,bear the world over after the ancient name given it1 but it requires some stretch of the imagination to liken it to that nubbly short-tailed animal4 ,all these fancy names were given this great group of stars long before the birth of ,christ and by these names the constellation is still familiarly called4 ,astronomers of the present time also call this constellation the ,great ,bear1 but they say it in ,latin and so it becomes ,ursa ,major1 which is a very high toned and scholastic sounding word4 ,but the ,big ,dipper is a name that is good enough for all ordinary purposes and so we'll use it4 ,illustration3 ,,fig4 #f4--,,the ,,big ,,dipper ,,as ,,we ,,see ,,it4 ,the stars forming the ,big ,dipper stand out so bright and clear in the northern sky that you won't have the slightest trouble in finding it1 especially if you have the star finder at hand to help you4 ,in using the star finder there is one thing you should keep well in mind and that is that the ,big ,dipper as we see it turns round the ,north ,star1 like the hands of a clock1 but in the opposite direction4 ,that is1 the ,big ,dipper1 when below the ,north ,star1 seems to turn round the ,north ,star from left to right4 ,illustration3 ,,fig4 #g4--,,the ,,great ,,bear ,,as ,,the ,,ancients ,,saw ,,it4 ,in a word the ,north ,star forms one end of the axis round which not only the ,big ,dipper but the whole starry heavens seem to revolve as though they were fastened to the spokes of a great wheel4 ,this is the way it seems to us4 ,as a matter of fact1 though1 all the stars are fixed in their positions in the sky1 and the reason they seem to revolve round the ,north ,star is because the ,earth from which we see the stars turns round instead4 ,illustration3 ,,fig4 #h4--,,the ,,earth1 ,,pole ,,star ,,and ,,dog ,,star4 ,by looking at the drawing shown in ,fig4 #h1 it will be seen that the north pole of our ,earth is directly under the ,north ,star1--hence the name ,pole ,star--and that if we could draw a line through the center of the ,earth from the south pole to the north pole and extend the line far enough1 or produce it as it is called1 it would finally meet the ,north ,star4 ,let us take1 now1 another star1 called the ,dog ,star--its real name is ,sirius 7pronounced ,sir-i-us7--which is not far from a line with and overhead of the ,earth's equator2 suppose we are some place on the earth where we can see both the ,north ,star and the ,dog ,star at the same time1 and keeping in mind that the ,earth is turning round on its axis2 it must be plain1 then1 that though both of these stars are fixed in the sky and never change their positions we on the ,earth will turn away from the ,dog ,star until the ,earth has turned half way round1 but we will not turn away from the ,north ,star4 ,the eye1 however1 is easily deceived2 for example1 if we are on a moving train nearby objects1 such as houses1 trees1 etc41 will seem to be moving in the opposite direction to which we are going while we seem to be standing perfectly still4 ,the illusion is much more complete when we are seeing the stars1 for the motion of the ,earth as it spins on its axis and shoots round the ,sun in its orbit is so steady that we cannot notice it2 for this reason it seems as if it is the stars which are moving and that we are standing still4 ,it is easy to understand now why the ,big ,dipper1 and all the other stars1 seem to move in great circles round the ,north ,star as well as why the ,big ,dipper marked with cardboard stars on your chart may not have the same relative position to the horizon as the ,big ,dipper of real stars in the northern sky1 when you view them together as in ,fig4 #d4 ,not only does the revolution of the ,earth on its own axis once in every #bd hours cause the ,big ,dipper to seem to turn round the ,north ,star1 but the yearly journey of the ,earth round the ,sun makes a change in the position of the ,big ,dipper as we see it at different seasons of the year4 ,and what has been said about the ,big ,dipper is just as true of all the other constellations4 ,for these reasons we would need an almanac to help us keep track of the exact hour when the ,big ,dipper would be in a given position for every night in the year4 ,but you can always find the ,big ,dipper any evening in autumn about nine o'clock1 by remembering that it is turned right side up as shown in ,figs4 #c and #d4 ,again1 if you look for the ,big ,dipper in winter at about nine o'clock in the evening you will find it standing on its handle a little to the east as in ,fig4 #i4 ,in spring about #i o'clock1 it will have moved on round the ,north ,star until it is upside down1 as in ,fig4 #aj1 while in summer1 at #i1 it is hung up by its handle high in the sky1 as shown in ,fig4 #aa4 ,the four positions of the ,big ,dipper during the same hours of the different seasons are shown in ,fig4 #ab1 which also shows the four positions of the ,big ,dipper during each #bd hours4 ,illustration3 ,,fig4 #i4--,,the ,,north ,,star ,,and ,,big ,,dipper ,,in ,,winter4 ,by turning the chart round on the board counter-clockwise you will soon come to a point where the ,big ,dipper of paper stars and the ,big ,dipper of real stars are in exactly the same position4 ,illustration3 ,,fig4 #aj4--,,the ,,north ,,star ,,and ,,big ,,dipper ,,in ,,spring4 ,you have1 no doubt1 noticed that a line joins the two end stars of the ,big ,dipper and the ,north ,star in ,figs4 #c1 #d1 #aj1 and #aa4 ,these two end stars of the ,big ,dipper are called pointer stars1 for they point directly to the ,north ,star2 that is if we draw a line with the eye through the pointer stars and produce1 or continue the line1 it will run into the ,north ,star1 nearly4 ,by using these pointer stars it is easy for any one who knows the ,big ,dipper to be able to find the ,north ,star on any clear night in the year1 for the ,big ,dipper can be seen the year round4 ,the seven stars which form the ,big ,dipper are not the brightest stars in the sky by any means1 yet each one is a great white sun as large or larger than our own ,sun4 ,illustration3 ,,fig4 #aa4--,,the ,,north ,,star ,,and ,,big ,,dipper ,,in ,,summer4 ,now look sharply at the middle star in the handle of the ,big ,dipper1 whose name is ,mizar 7pronounced ,me-zar71 and see if you can make out another little star whose name is ,alcor 7pronounced ,al-cor7 hugging up close to it4 ,the ,arabs who named them called these two stars the ,horse and its ,rider4 ,if you can see this little star ,alcor you will have cause to shake hands with yourself1 for if your eyes are good you can see it and if they are only fair to middling you cannot see it4 ,this is one of the famous ,arab tests for eyesight4 ,illustration3 ,,fig4 #ab4--,,telling ,,time ,,by ,,the ,,big ,,dipper4 ,how to ,tell ,time by the ,big ,dipper4--,we have seen how the ,big ,dipper seems to turn round the ,north ,star and this being the case we can use the pointer stars for the hour hand of a big star clock4 ,you must always bear in mind1 though1 that while the hands of a clock turn from right to left1 the ,big ,dipper swings round from left to right2 and there is another thing to be kept in mind and that is while the hour hand of a clock goes twice round in #bd hours1 the ,big ,dipper revolves only once in #bd hours1 and for this reason the hand formed by the pointer stars of the ,big ,dipper moves only half as fast as the hour hand of a watch or clock4 ,each quarter of the circle1 then1 is equal to #f hours and by dividing the quarter circles into #f equal parts you can mark off the hours4 ,the best way to do this at first is to make a large drawing of ,fig4 #ab on your starboard and compare it with the ,big ,dipper2 then draw an imaginary circle round the ,north ,star in the sky so that it will just clear the last star in the handle of the ,big ,dipper4 ,with some practice you will be able to tell the time within half an hour or less4 ,in telling the time by the ,big ,dipper you must remember that the stars in turning round the north pole run fast an hour every #ae days1 and this makes them gain #f hours in #c months and so they gain a complete revolution in a year4 ,but every time the ,big ,dipper makes one complete turn round the ,north ,star1 one complete day1 as measured by star time1 will have passed4 ,the ,pointers of the ,big ,dipper are in the four positions1 shown in the figure1 on the following dates at #h ,p4,m43 ,may #a1 #bdth hour2 ,aug4 #a1 #fth hour2 ,nov4 #a1 #abth hour2 ,feb4 #a1 #ahth hour4 ,in the same way1 on ,sept4 #a at #h ,p4,m4 the pointers will be at #h and they will also be there at #g ,p4,m4 on ,sept4 #af4 ,,chapter ,,ii ,,how ,,to ,,know ,,the ,,stars ,one of the tests a ,boy ,scout must pass in order to obtain his badge of merit for starcraft is to be able to name and point out twelve principal constellations1 and every boy1 whether he is a scout or not1 should be able to do the same thing for his own good4 ,the word constellation is formed from two ,latin words1 the first being con which means together1 and the last being stella which means star1 or in plain ,english1 constellation means stars together4 ,in your efforts to find the ,north ,star you have already learned one of the principal constellations--that of the ,big ,dipper--and to learn more of them will be even easier and much more fun1 for now you have learned the game4 ,the ,constellation of ,cassiopeia4--,to find the constellation of ,cassiopeia 7pronounced ,cas-i-o-pe-ah7 again make use of your star finder4 ,remove all the stars from the blackened cardboard and rearrange them so that the ,north ,star is in the center of the board and the ,big ,dipper is on the left hand side with the two pointer stars in a line with the ,north ,star4 ,on this chart the ,big ,dipper must be made much smaller than the one described in the first chapter4 ,cut out five more stars from white cardboard and place them on the opposite side of the board from the ,big ,dipper in such a manner that they will form the letter ,w being careful to fasten the stars to the cardboard so that the letter ,w stands in the exact position shown in ,fig4 #ac4 ,a line drawn through the pointers of the ,big ,dipper and produced will1 as before1 pass through the ,north ,star1 and if it is extended an equal distance beyond it1 will pass very closely to the constellation of ,cassiopeia2 this line will aid you in placing the stars on your chart in the right positions4 ,having thus prepared the star finder1 take it out into the open when night comes on and begin by locating the ,north ,star and the ,big ,dipper4 ,now set the ,big ,dipper and the ,north ,star of your star chart in a position which to your eye corresponds to the ,big ,dipper and the ,north ,star in the sky4 ,follow the line from the pointer stars to the ,north ,star and beyond when the great letter ,w which is the constellation of ,cassiopeia1 will stand out so clear and bright that you will wonder why you have never seen it before4 ,illustration3 ,,fig4 #ac4--;,,constellation ,,of ,,cassiopeia4 ,fig4 #ad shows this group of stars and the outline of the unhappy ,cassiopeia who is as often standing on her head as on her feet1 but it requires the imagination of an ,arabian star-gazer to see the likeness4 ,the ,little ,dipper4--,although some of the stars which form the ,little ,dipper are very faint it is included in our list of #ab principal constellations for two reasons3 first1 because it contains the very important ,north ,star1 and second1 because it is easy to find4 ,illustration3 ,,fig4 #ad4--;,,cassiopeia ,,as ,,the ,,arabs ,,saw ,,her4 ,illustration3 ,,fig4 #ae4--,,the ,,little ,,dipper ,,or ,,little ,,bear4 ,the ,north ,star is the last star in the handle of the ,little ,dipper4 ,the two outer stars which form the bowl of the ,little ,dipper1 and which are called the ,guardians of the ,pole1 are quite bright1 and after a few trials you can easily put in the other stars that are much fainter1 and so complete in your mind's eye the outline of the ,little ,dipper as you have it on your chart4 ,fig4 #ae shows the arrangement of the stars in the ,little ,dipper and the relative position of the ,little ,dipper to the ,big ,dipper4 ,the ,little ,dipper is also called the ,little ,bear and this latter name when done into ,latin becomes ,ursa ,minor1 which is its scientific name4 ,how the ,little ,dipper was made into a ,little ,bear by the ancients is shown in ,fig4 #af4 ,the ,great ,square of ,pegasus4--,unlike the ,big ,dipper1 the ,little ,dipper and ,cassiopeia1 which are so close to the ,north ,star that they never set and hence can be seen at any hour of the night and at any season of the year1 we now come to some constellations which are quite distant from the ,north ,star and are for this reason to be seen only at certain times of the year4 ,the ,great ,square of ,pegasus can always be seen on clear1 crisp nights during the autumn months4 ,illustration3 ,,fig4 #af4--,,the ,,little ,,dipper ,,made ,,into ,a ,,little ,,bear4 ,to find a constellation that is as far away from the ,north ,star as ,pegasus 7pronounced ,peg'-a-sus7 is not an easy thing to do1 at least the first time you try it1 for while our chart is marked with a straight line the sky is like a great bowl and a line produced from the ,north ,star to ,pegasus will1 in consequence1 not be a straight line1 but a curved line4 ,however1 with your star finder charted like the diagram shown in ,fig4 #ag you will be able to locate ,pegasus with very little effort4 ,after taking off all the stars from the cardboard surface1 pin or paste the ,north ,star to the lower left hand corner of the black surface of the cardboard and place the five stars of ,cassiopeia in their proper positions4 ,now draw a line from the ,north ,star through ,cassiopeia just below the star marked which is the ,greek letter beta 7see ,appendix ,c7 and produce1 or extend that line until the edge of the cardboard is reached4 ,on the extreme right hand end of this line set two stars1 which we will also call pointer stars1 and place two more stars above them so that a nearly perfect square will be formed as shown in ,fig4 #ag4 ,illustration3 ,,fig4 #ag4--,,the ,,great ,,square ,,of ,,pegasus4 ,to find ,pegasus take the star chart out-of-doors1 say some evening in ,november about #i o'clock1 for the ,great ,square will then be on the meridian1 that is1 on a line passing over your head and which runs north and south across the sky4 ,this time1 instead of looking down on the chart1 as you did in finding the ,big ,dipper and ,cassiopeia1 turn the board bottom side up1 as shown in ,fig4 #ah1 but still keeping the cardboard ,north ,star pointing north and the four stars of ,pegasus pointing toward the south4 ,by looking over your chart into the sky and following an imaginary line with your eye from the ,north ,star through ,cassiopeia past the star 7beta7 and lengthening this line toward the equator in the southern sky you will come upon four bright1 white stars which form the ,great ,square of ,pegasus and you have added another and fourth constellation to your list4 ,the practical value of knowing the mighty constellation of ,pegasus is that you can always find the north1 by means of its friendly stars1 though the ,north ,star1 the ,big and ,little ,dippers and ,cassiopeia are hidden by clouds4 ,to find the north you only have to wait until ,pegasus gets very high in the sky and run an imaginary line through the pointer stars of ,pegasus and produce it until it reaches the northern horizon4 ,illustration3 ,,fig4 #ah4--;,,holding ,,the ,,chart ,,of ,,pegasus ,,overhead4 ,the ,great ,square of ,pegasus was fancifully pictured by the ancients as a ,flying ,horse and1 curiously enough1 with only half a body at that1 as shown in ,fig4 #ai4 ,to those who do not know the lore of the stars it is not so easy to see in the ,great ,square the fabled winged steed who still continues his flight through the sky just as he did when he was invented over four thousand years ago4 ,illustration3 ,,fig4 #ai4--,,the ,,flying ,,horse ,,of ,,pegasus4 ,illustration3 ,,fig4 #bj4--;,,figure ,,of ,a ,,trapezium4 ,the ,mighty ,orion4--,the brightest constellation in the whole sky is ,orion 7pronounced ,o-ri-on71 the ,great ,hunter1 as the ancients liked to imagine this group of stars4 ,with the exception of the ,big ,dipper1 ,orion is the easiest of all the constellations to find provided you look for it at the right time of the year1 which is during the winter months4 ,to locate ,orion cut out of cardboard seven large stars and three small stars4 ,near the lower edge of the blackened cardboard pin two large and two small stars to form what is called a trapezium1 that is1 four straight lines forming a figure1 none of which are parallel1 as shown in ,fig4 #bj4 ,about halfway across the figure pin three large stars in a row1 at equal distances apart and tilted a little1 as shown in ,fig4 #ba4 ,illustration3 ,,fig4 #ba4--;,,constellation ,,of ,,orion4 ,illustration3 ,,fig4 #bb4--,,orion ,,the ,,mighty ,,hunter4 ,these three stars form the ,belt of ,orion1 for a mighty hunter must needs have a belt1 and this belt of bright stars is one of the best known groups in the whole sky4 ,across the belt and nearly at right angles to it pin three small stars2 these small stars form the sword or dagger of the fanciful hunter but they are of more use to us than to him1 as will be seen presently4 ,at the top of the star chart pin the ,north ,star so that it will be in a direct line with the three small stars forming the ,sword of ,orion4 ,your star chart of ,orion is now ready to be compared with the one in the sky4 ,the best time to find ,orion is in ,january about #i o'clock1 when the constellation is high in the southern sky1 though he may be seen shining in all his glory all winter long4 ,on taking your star chart out-of-doors hold it overhead just as you did in finding the ,great ,square of ,pegasus2 now look toward the south until your eyes rest on the equator running across the southern sky from east to west and you will see the mighty ,orion1 though you may not recognize the lion skin he holds4 ,having found ,orion draw an imaginary line through the three small stars called his sword and produce this line until it meets the ,north ,star4 ,once you have found ,orion you will never again require the help of a star chart to locate him1 but it is a good plan to look him up as often as you can1 and to draw the imaginary line through his sword and on to the ,north ,star1 for should you ever lose your way or want to find the north and the ,north ,star should be hidden by clouds a line through the ,sword of ,orion when ,orion is in the south will direct you as certainly as the needle of a compass4 ,fig4 #bb shows the fabulous ,orion as a giant hunter holding the skin of a lion which he killed1 according to ,arabian star-lore4 ,illustration3 ,,fig4 #bc4--;,,constellation ,,of ,,auriga4 ,illustration3 ,,fig4 #bd4--;,,auriga ,,the ,,shepherd4 ,auriga1 the ,charioteer or ,shepherd4--,after finding ,orion the constellation of ,auriga 7pronounced ,aw-re-ga7 will get right in your way so that you cannot by any chance miss it4 ,this is because the chief star in ,auriga and whose name is ,capella 7pronounced ,ca-pel-la7 lies nearly on the line drawn through the ,sword of ,orion and produced to the ,north ,star as shown in ,figs4 #ba1 #bc and #bg4 ,auriga was pictured by the ,assyrians as a charioteer1 but the early ,greeks saw in this constellation a good shepherd1 who carried a goat on his back and two kids in his arms4 ,the brilliant star ,capella is supposed to be the goat and the three small stars which form a triangle close to ,capella are the kids as shown in ,fig4 #bd4 ,when the ,north ,star cannot be seen the star ,capella will prove a useful aid with ,orion in finding the north2 and since it is just about half way between ,orion and the ,north ,star it may again be useful in judging the distance of the ,north ,star from ,orion when the former star is obscured4 ,the ,constellation of ,taurus4--,the last constellation which need concern us here is ,taurus 7pronounced ,to-rus7 the ,bull4 ,taurus is one of the constellations of the zodiac of which we will have something to say in ,chapter ,,xi4 ,by the time you have learned the foregoing constellations you will be able to locate ,taurus without using your star chart1 for it lies to the north of ,orion1 to the south of ,auriga and a little to the west of both of these constellations as you will see in ,figs4 #be and #bg4 ,illustration3 ,,fig4 #be4--;,,constellation ,,of ,,taurus4 ,illustration3 ,,fig4 #bf4--,,taurus ,,the ,,bull4 ,the little group of stars nearby is the ,pleiades 7pronounced pl-ya-dez71 and is a part of the constellation of ,taurus4 ,there are six small but bright stars grouped closely together when seen by the ordinary person1 but if you have very sharp eyes you may be able to make out one or two more4 ,it is believed that the stars of ,taurus were the first to be woven into a group or constellation by the ancients1 and it is thought that the ,bull of ,light1 as ,taurus was called1 was known long before the time of ,abraham1 or over four thousand years ago4 ,fig4 #bf shows ,taurus as the ,egyptians saw him4 ,the bright red star which sets in the right eye of ,taurus is called ,aldebaran 7pronounced ,al-deb-a-ran7 and is one of the brightest stars in the sky4 ,in the star chart shown in ,fig4 #bg the different constellations you have learned are grouped together in the same positions in which they are placed in the sky4 ,illustration3 ,,fig4 #bg4--,,star ,,map ,,showing ,,six ,,chief ,,constellations4 ,six stars of the first magnitude1 that is #f of the #bj stars which shine the brightest 7see ,appendices ,f and ,g71 are also shown on the chart1 ,fig4 #bg4 ,by following the equator from west to east across the bowl of the sky1 and which runs right through the middle of ,orion1 you will find to the west and south of it the brightest star in the heavens--,sirius1 the ,dog ,star1 so named because it is in the constellation of ,canis ,major1 which is ,latin for ,big ,dog4 ,of the other stars on the chart1 ,capella in ,auriga is the next brightest star1 and ,arcturus 7pronounced ,arc-tu-rus7 which can be found by following the handle of the ,big ,dipper1 is third in brilliancy4 ,the fourth place is held by ,rigel 7pronounced ,rai-gel7 in ,orion2 ,betelgeux 7pronounced ,bet-el-gerz7 in ,taurus is fifth in order1 and ,aldebaran in ,orion comes last4 ,there are many other constellations and a large number of other stars but when you are able to name and point out those described in this chapter you will have made a very good running start4 ,,chapter ,,iii ,,the ,,sun1 ,,the ,,brightest ,,of ,,all ,,stars ,in naming over the stars of the first magnitude--that is1 the stars that shine the brightest--there is one star ,i did not mention and yet as we see it it is brighter than all the other stars put together4 ,this great star is our ,sun and since we owe everything we possess on ,earth to him--light1 heat1 power and even life itself--he should and does stand in a class by himself1 though after all he is just as much of a fixed star as the ,north ,star1 the ,dog ,star1 or any of the thousands of other stars which we see as mere points of light in the sky4 ,how to ,see the ,sun4--,you must never look directly at the ,sun with the naked eye1 for he is so powerful that his light will injure your sight for all time4 ,illustration3 ,,fig4 #bh4--,,smoking ,,glasses ,,over ,,candle ,,flame4 ,illustration3 ,,fig4 #bi4--,,seeing ,,the ,,sun ,,through ,,smoked ,,glasses4 ,there are several ways1 though1 to observe the ,sun without danger to your eyes and as all of these are simple and cost nothing you can easily try them4 ,the most common way is to take a bit of window glass1 say an inch square1 and smoke one side of it over the flame of a candle1 as shown in ,fig4 #bh4 ,when this blackened glass is held closely to the eye1 as shown in ,fig4 #bi1 and the latter is directed toward the ,sun1 a little circle of light will appear on the film of smoke and the surface of the ,sun may be examined at length and without the least danger4 ,a decided improvement over the smoked glass idea is to use a piece of red1 or a piece of yellow glass1 as an eyepiece1 or1 better1 place the red and yellow glasses together and bind the edges with paper4 ,another plan to see the ,sun without injury to the eyes is to make a hole with the point of a needle in a visiting card and look through the hole directly at the ,sun4 ,a still better view of the ,sun can be obtained if a pinhole telescope is used4 ,a telescope of this kind can be easily made without tools1 metals or lenses4 ,it is described and pictured in ,chapter ,,ix4 ,to observe the ,sun hold the pinhole end of the tube closely to your eye1 to cut off all the outside light1 and sight the tube so that the ,sun shines directly into your eye through the pinhole1 and you will get a very brilliant view of the great yellow star which we call the ,sun4 ,what the ,sun is ,made of4--,when a candle is lit the wax of which it is made begins to melt and this is drawn up the wick where it is changed into gas and the burning gas forms the flame4 ,the flame of a candle is made up of four parts1 which are really layers of heated gas surrounding the wick1 as shown in ,fig4 #cj4 ,in the center of the flame is the wick2 the first layer of gas is at the bottom of the flame and this gives a greenish-blue light2 the second layer is the dark and cool part of the flame2 the third layer is a cone of heated gas which gives out the bright light1 and surrounding this cone is a faint blue light which can just be seen4 ,we know1 of course1 what the candle is made of and we also know why it burns and in a way how it gives off light and heat because we have examined it closely1 but if we could get no nearer a candle flame than a quarter of a mile it is very doubtful if we could ever be able to learn anything about the real source of the flame--that is its greasy wick4 ,illustration3 ,,fig4 #cj4--;,a ,,candle ,,flame ,,showing ,,layers ,,of ,,flame4 ,it is much the same with the ,sun1 for we can only examine it at a great distance and know it by its action on our senses1 for the flaming layers of the ,sun are so bright that no one ever saw through them1 so the real source of its light and heat--the core of the ,sun--remains unknown4 ,fig4 #ca shows the ,sun as seen with a field glass4 ,since the ,sun gives out light and heat it is easy to believe that it is a great ball of very hot gases and from what astronomers have learned of him with their wonderful instruments this idea seems to be pretty well founded4 ,the ,sun must be a tremendously hot body--for the iron and other metals in it are not only melted but they boil away like water and are changed into gases4 ,under certain conditions gigantic flames1 called prominences1 shown in ,fig4 #cb1 can be seen to leap from the edge1 or limb1 as it is called1 of the ,sun1 and finally1 great spots1 called sun spots1 are formed on the ,sun that are so large a dozen worlds the size of our ,earth could be dropped into any one of them and rattled around like marbles in a cigar box4 ,these are a few of the reasons we are led to believe that the ,sun is a seething ball of fire4 ,the ,sun's ,layers of ,flame4--,just as the wick of a candle is surrounded with several kinds of flame1 so the ,sun has three layers of flame around a central core4 ,the core of the ,sun is believed to be formed of liquid gases which are about as thick as ,new ,orleans molasses4 ,around this core1 which is the real source of the ,sun's light and heat--and which has never been seen--is a dark layer of flame usually called the ,sun's surface2 this layer1 which is covered with numerous dark spots like freckles on the face of a red-headed boy1 is called the photosphere1 and it is this part of the ,sun which gives out the most light4 ,illustration3 ,,fig4 #ca4--,,the ,,sun ,,as ,,we ,,see ,,it4 ,the second layer1 which is called the chromosphere1 is about #e1jjj miles thick1 and if you could imagine the whole world afire you would then have but a faint idea of what a mighty seething sea of flame this layer is4 ,it is in this layer of luminous gases that terrific explosions take place and red tongues of flame1 or prominences1 are shot out for upwards of #cjj1jjj miles4 ,around the chromosphere is another layer of flame which extends for hundreds of thousands of miles in all directions4 ,this last layer is called the corona1 and it is as thin as the stuff of which dreams are made4 ,it is formed of the gas coronium and since it is so thin it can never be seen except when there is a total eclipse1 that is1 when the ,moon passes between us and the ,sun1 which will be explained in ,chapter ,,vii1 and so shuts out the intense light of the other two layers4 ,a cross section of the ,sun is shown in ,fig4 #cc4 ,illustration3 ,,fig4 #cb4--,,prominences ,,of ,,the ,,sun ,,compared ,,with ,,the ,,size ,,of ,,the ,,earth4 ,sun ,spots and ,their ,effect on the ,earth4--,very often great spots are seen on the ,sun's surface4 ,these purplish black spots appear to be holes1 like the craters of volcanoes1 in the photosphere1 or layer of flame next to the core of the ,sun4 ,the sun spots are caused by great eruptions which take place in the core of the ,sun1 and these sun spots are sometimes over #ajj1jjj miles in diameter1 when they can be easily seen with the naked eye2 indeed if a sun spot has a diameter only as large as that of our ,earth1 it can be seen with the naked eye1 protected1 of course1 with either a smoked or a colored glass1 or better1 with a pinhole telescope2 in any case it will look like a black speck about the size of a pinhead4 ,fig4 #cd shows a view of a sun spot made through a large telescope4 ,illustration3 ,,fig4 #cc4--;,,cross ,,section ,,of ,,the ,,sun4 ,whenever the sun changes his spots magnetic storms take place on the ,earth1 when compass needles1 telegraph and telephone apparatus and wireless systems are disturbed4 ,when a large number of spots appear at the same time on the ,sun the ,northern ,lights are often very bright4 ,sun spots have something to do with our weather1 but the effects are not yet well understood4 ,the ,sun and the ,weather4--,of course the ,sun has everything to do with the weather1 but to be able to predict the kind of weather we shall have even the next day is a very hard thing to do4 ,the changes in the weather are caused by the heat of the ,sun alone4 ,the heat of the ,sun produces clouds by vaporizing the water of rivers1 lakes and oceans4 ,he causes hot and cold weather by heating some parts of the air more than other parts1 and this sets the air in motion and we call this movement of the air the wind4 ,illustration3 ,,fig4 #cd4--,,sun ,,spot ,,in ,,photosphere4 ,changes of heat1 moisture and wind are the cause of all the kinds of weather we have1 and we have a good many kinds1 be it hot or cold1 dry or wet1 calm or windy1 clear or stormy1 good1 bad and indifferent4 ,to ,forecast the ,weather by a ,barometer4--,the best way to tell what the coming weather will be in the next few hours is by the rise and the fall of the pressure of the air1 or barometric pressure1 as it is called4 ,a simple barometer for showing the changes in the pressure of the air can be made of a glass tube about #c feet long1 inch in diameter1 and closed at one end as shown in ,fig4 #ce4 ,fill the tube with mercury and1 placing your finger over the mouth of the tube1 turn it upside down and put the open end into a cup1 or other vessel1 which is half full of mercury2 in placing it into the cup be careful that no air gets into the tube4 ,only a small part of the mercury in the tube will run into the cup and this will leave a space in the top of the tube4 ,now fasten a yardstick1 the purpose of which is to show the changes in the height of the mercury in the tube1 with a string or wire to the tube1 and your barometer will be complete1 as shown in ,fig4 #cf4 ,since the air presses on the mercury in the cup but not in the tube1 the pressure of the air on the mercury in the cup just balances the weight of the mercury in the tube and1 hence1 any increase or decrease in the pressure of the air1 which ordinarily is about #ae pounds to the square inch1 is shown by the rising or the falling of the mercury in the tube4 ,the barometer in helping to forecast the weather shows that3 7#a7 when the mercury rises in the tube1 that is when it is high1 the weather will be fair2 7#b7 when the mercury falls in the tube1 that is when it is low1 bad weather may be looked for2 7#c7 when the mercury suddenly falls in the tube a storm is coming1 and 7#d7 when the mercury continues at a high point the weather will remain fair4 ,illustration3 ,,fig4 #ce4--;,,barometer ,,tube4 ,illustration3 ,,fig4 #cf4--;,,barometer ,,complete4 ,to remember these forecasts easily they may be briefly stated thus3 7#a7 ,a high barometer shows fair weather4 7#b7 ,a low barometer shows bad weather4 7#c7 ,a sudden fall of the barometer shows a coming storm4 7#d7 ,a constant high barometer shows continued fair weather4 ,to ,forecast the ,weather by ,signs4--,it will seldom happen that a boy who goes camping1 or one who otherwise wants to know what the weather is likely to be on the morrow1 will have a barometer to consult1 so the next best thing is to know how to read the weather signs3 7#a7 8,red at night is the sailor's delight0 is an old forecast1 and means that the morrow will be a fine day4 7#b7 8,red in the morning is the sailor's warning10 which means that rain is coming4 7#c7 ,a golden sunset is a sign that a high wind is coming4 7#d7 ,a yellow sunset is a sign that rain is coming4 7#e7 ,when the ,sun sets clear it is a sign of a fine day on the morrow4 7#f7 ,when the ,sun sets behind a cloud it is a sign that the next day will be cloudy or rainy4 7#g7 ,a misty dawn shows the coming of a fine day4 7#h7 ,a low dawn1 that is when the ,sun shines clear on rising1 shows the coming of a fine day4 7#i7 ,a high dawn1 that is when the ,sun rises over a haze1 or clouds1 shows wind4 ,to ,light a ,fire with the ,heat of the ,sun4--,a small magnifying glass1 or burning glass1 is simply a convex lens4 ,it is a little piece of apparatus that every boy should always carry with him just as he does his pocket knife and compass4 ,a lens #a inches in diameter and having a #d-;inch focus may be bought for #be or #cj cents4 ,a lens of this kind will be found very useful in many ways1 for it will greatly magnify any object such as cloth1 leaves1 insects1 finger-prints1 in fact anything you may wish to see better than you could with your naked eye1 though you cannot use a single lens for a spyglass4 ,a magnifying glass will also frequently come in handy for lighting fires1 by using the ,sun's rays when matches are scarce4 ,while a ,boy ,scout would disdain to use paper to kindle a fire1 yet if a scrap of paper is at hand it will prove a good medium on which to direct the rays of the ,sun with a burning glass4 ,if you have no paper focus your glass on some punk or very dry leaves1 as shown in ,fig4 #cg4 ,to focus the glass means to hold it away from the paper or leaves so that the rays of the ,sun are brought to a point like the sharpened end of a lead pencil2 when all the rays of sunlight1 each of which carries a little heat1 are brought to a point1 they will make enough heat to light a piece of paper or a dry leaf4 ,illustration3 ,,fig4 #cg4--;,,boy ,,focusing ,,burning ,,glass ,,on ,,leaves ,,to ,,make ,,fire4 ,signaling with the ,sun's ,rays4--,there are many ways of sending a signal or a message across space by day1 as1 for instance1 by means of smoke1 by flags and flashes of sunlight2 by bonfires1 pine-knot flames and burning arrows by night1 and by wireless1 which can be used either by day or by night4 ,a simple and effective way to signal in the daytime when the ,sun is shining is by using a mirror1 that is1 a looking-glass1 as it is commonly called4 ,every boy knows how to make flashes with a mirror1 so it will be enough to say here that the glass is held in the hand in such a position that the sunlight falling upon it will be reflected in the direction you wish to send the signals4 ,fig4 #ch shows how it is done4 ,illustration3 ,,fig4 #ch4--;,,boy ,,sending ,,flash ,,signal ,,with ,,mirror4 ,illustration3 ,,fig4 #ci4--;,,continental ,,morse ,,code4 ,any sort of a code can be used1 but it is far more interesting and will prove very useful if you are able to send and receive messages in the dot and dash alphabet1 or ,morse telegraph code1 which is given in ,fig4 #ci4 ,a short flash represents a dot1 a long flash a dash and short and long flashes represent letters4 ,this is the same code that is used for wireless telegraphy4 ,how to ,make a ,simple ,heliograph4--,a heliograph is merely a mirror mounted on a baseboard1 but this is a big improvement over holding the mirror in the hand1 for to send and receive flashes over long distances the mirror must be carefully aimed and kept in position4 ,to make a heliograph1 get a board #ab inches long1 #d inches wide and #a inch thick and cut a piece out of one end #d inches long and #a inch wide1 as shown in ,fig4 #dj4 ,bore a inch hole through the slotted end and another inch hole #d inches from the slotted end1 as shown in the cut4 ,illustration3 ,,fig4 #dj4--;,,base ,,for ,,heliograph4 ,illustration3 ,,fig4 #da4--;,,back ,,view ,,of ,,heliograph4 ,make a block of wood #d inches long1 #a inch wide and #a inch thick and bore a inch hole through it near one end4 ,to the other end of this stick fasten a mirror about #d inches square4 ,this mirror should be perfectly smooth--a plate glass mirror is the best--and have a hole _/ inch in diameter drilled through the center of the mirror for sighting the heliograph1 as shown in ,fig4 #da4 ,any optician will drill the hole for you for a quarter or less4 ,fig4 #db shows a top view of the heliograph and ,fig4 #dc shows a side view of it4 ,make a wood frame so that the mirror can be fastened in it and screw the frame to a stick of wood4 ,get a bolt #e inches long and inch in diameter and have a thumb screw fitted to it4 ,set the end of the stick which has the mirror fastened to it into the slotted end of the baseboard1 push the bolt through the holes and after slipping on the washer put on the thumb screw4 ,the mirror can now be moved to and fro4 ,illustration3 ,,fig4 #db4--,,top ,,view ,,of ,,heliograph4 ,illustration3 ,,fig4 #dc4--,,side ,,view ,,of ,,heliograph4 ,into the hole in the front part of the base put a wire or a thin round stick to sight the mirror by4 ,the heliograph is now ready for use4 ,after sighting the mirror at the place where the signals are to be received1 set the mirror so that the reflected beam of sunlight shines directly on the place4 ,to send signals in the ,morse code all you need to do to make dots and dashes is to place a sheet of cardboard before the mirror and take it away2 the length of time the mirror remains uncovered determines whether it is a dot or a dash4 ,the heliograph complete is shown in ,fig4 #dd4 ,illustration3 ,,fig4 #dd4--;,,heliograph ,,complete4 ,how to ,make a ,simple ,sundial4--,to make a sundial of the usual kind that will give the correct ,sun time is not an easy matter1 for the spaces marking the hours on the dial are not equal as they are on the face of the clock and this will make it hard to figure out4 ,a kind of sundial that will give the correct ,sun time though1 can be easily made and at little cost4 ,get a strip of tin #b inches wide and #bd inches long2 mark it off into #bd equal spaces like those on a two-foot rule1 and beginning at one end with the number #a1 number each space to #bd1 as shown in ,fig4 #de4 ,this done1 bend the strip of tin into a perfect ring with the numbers inside and solder the joint1 as shown in ,fig4 #df4 ,illustration3 ,,fig4 #de4--,,numbered ,,strip ,,for ,,sundial4 ,illustration3 ,,fig4 #df4--,,tin ,,ring ,,for ,,sundial4 ,next get a strip of iron or brass inch wide1 _/ inch thick and #ac inches long2 drill a _/ inch hole through each end and a inch hole #d inches from one end2 bend this strip into an exact semi-circle1 as shown in ,fig4 #dg and solder the tin ring1 at the point where numbers #a and #bd meet1 to the middle of the brass semi-circle4 ,through the holes in the ends of the brass semi-circle fasten a wire1 and this wire must run exactly through the center of the tin ring4 ,now screw the brass semi-circle to a baseboard 7see ,fig4 #dh71 so that the angle made by the wire and the surface of the board will be equal to the latitude of the place where it is to be used2 in other words1 when the board is level the wire should point directly to the ,north ,star and when this is done it will be adjusted to the proper angle4 ,the board should be about #ab inches square and #a inch thick4 ,illustration3 ,,fig4 #dg4--;,,brass ,,semi-,,circle ,,with ,,shadow ,,wire4 ,illustration3 ,,fig4 #dh4--,,sundial ,,complete4 ,since the shadow of the wire made by the sunlight will fall on ,,xii at noon1 it will be plain that the shadow of the wire falling on the numbers on one side or the other of the ring will mark the ,sun time4 ,to change ,sun time to mean solar time1 or ordinary time1 see ,equation of ,time1 ,appendix ,m4 ,illustration3 ,,fig4 #di4--,,to ,,find ,,the ,,north ,,by ,a ,,watch4 ,to ,find the ,north by a ,watch4--,to use a watch as a compass1 that is to find the north by means of a watch1 is easy if the ,sun is shining4 ,the watch should be held face upward2 then turn the watch around until the hour hand points in the direction of the ,sun4 ,draw an imaginary line from the hour ,,xii to the center of your watch4 ,if1 now1 in the middle between this line and the hour hand you draw another line from the center of the watch and produce1 or extend it1 the middle line will point just about north1 all of which is clearly shown in ,fig4 #di4 ,,chapter ,,iv ,,the ,,planets1 ,,the ,,sun',s ,,kiddies ,in the last chapter we said that all the stars in the sky1 including our ,sun1 are fixed in their positions2 by this we mean that if we were to look at the ,big ,dipper every night for a hundred years we could see no change in the positions of any of the stars forming this constellation4 ,but if we look at the sky along the line of the ecliptic--that is the path of the ,sun--one night after another we are likely to see a bright point of light which looks exactly like a star and yet it is certain that this point of light really does move among the other stars4 ,what kind of a heavenly object then is this8 ,the bright point of light which thus seems to us to be a star when we look at it with the naked eye is really another world1 or planet as it is called1 and very like our own ,earth4 ,to prove that this moving point of light is really a world1 or planet1 and not a distant star1 all you need to do is to look at it through a pair of opera glasses1 or a small telescope1 when it will be seen to be a round body1 whereas a star when viewed through the greatest telescope is never larger than a mere point of light4 7,see ,fig4 #ej47 ,illustration3 ,,fig4 #ej4--;,a ,,star ,,and ,a ,,planet ,,in ,a ,,telescope4 ,the reason the planets1 some of which are smaller and some larger than our ,earth1 can be seen to move is because they are quite near our ,earth2 that is1 they are near when compared with the fixed stars4 ,again1 the reason the planets shine like the stars is not because they are hot and flaming bodies like our ,sun and the other stars1 but because the light from the ,sun which strikes them is reflected to the ,earth in exactly the same way that the sunlight falling on a mirror is reflected away in another direction4 ,names and ,sizes of the ,planets4--,the names of all the planets1 and there are eight chief ones1 should be learned as well as the order in which they are arranged around the ,sun4 ,the names of the planets are given below in the order of their size4 ,,mercury--,the smallest planet and the one nearest the ,sun4 ,pale ash in color4 ,has no moon4 ,,mars--,the ,red ,planet4 ,reddish in color4 ,has two moons4 ,,venus--,called the ,evening ,star4 ,brilliant straw in color4 ,has no moon4 ,,earth--,our own planet4 ,has one moon4 ,,uranus 7pronounced ,yew-ra-nus7--,called ,herschel's planet4 ,pale green in color4 ,has five moons4 ,,neptune--,the planet farthest away from the ,sun4 ,has one moon4 ,,saturn--,the planet with the rings4 ,its color is a dull yellow4 ,has ten moons4 ,,jupiter--,the largest planet4 ,he is marked with lines called belts4 ,he has nine moons4 ,bright silver in color4 ,,the ,,asteroids--,a group of small planets1 the largest of which is about #ejj miles in diameter4 ,how to ,know the ,planets4--,while it is not an easy thing to tell a planet from a star with the naked eye1 still there are several ways of doing it4 ,first1 always look for the planets along the path which the ,sun and ,moon travel4 ,as all the planets are nearly in the same plane with the ,sun and ,moon they must all follow the same path across the sky4 ,second1 it is useful to remember that none of the planets1 except ,mercury1 ever twinkle1 unless they are very near the horizon4 ,third1 by watching a planet closely for a few hours it will be found to have moved a little4 ,to note this change of position the planet and some fixed star near it must be closely watched and their distances compared from time to time4 ,fourth1 and last1 the surest way of finding the different planets is by using an almanac which will tell you which planets can be seen at certain times of the year and in what part of the sky they are to be found4 ,illustration3 ,,fig4 #ea4--,,sizes ,,of ,,planets ,,compared4 ,seeing ,mercury4--,mercury is so near the ,sun that it can only be seen with the naked eye at certain times4 ,mercury should be looked for just above the eastern horizon for about an hour before the ,sun rises in the spring2 and above the western horizon for about an hour after the ,sun sets in the autumn4 ,you will have no trouble in knowing ,mercury if you can only see him1 for he is very bright and will be near the horizon4 ,his pale ash color will also help you to single him out from the stars about him4 ,mercury goes through phases like our ,moon1 but these cannot be seen with the naked eye4 ,mercury is a curious planet in that his day and his year are of exactly the same length1 just like our ,moon2 this means that he turns on his axis once in exactly the same length of time it takes him to travel round the ,sun4 ,this causes one side of ,mercury to be always turned toward the ,sun1 and of course this side is hot and light1 while the other side is always turned away from the ,sun and1 consequently1 it is dark and cold4 ,three views of ,mercury in different phases as seen through a telescope are shown in ,fig4 #eb4 ,mercury is #cf millions of miles from the ,sun4 ,his diameter is #c1jjj miles4 ,his day is #hh of our days long4 ,his year is #hh of our days long4 ,illustration3 ,,fig4 #eb4--,,three ,,views ,,of ,,mercury4 ,seeing ,mars4--,we hear more of ,mars than of any other planet for two reasons3 first1 because great lines can be seen on his surface which are thought to be canals1 and second1 since ,mars sometimes comes almost as close to the earth as ,venus1 there has been a great deal of talk since the invention of wireless telegraphy about our signaling to him4 ,that people could live on ,mars is possible1 for the ,red ,planet is like our ,earth1 in that it has land1 water and air1 weather and seasons1 with a warm equator and ice-covered poles4 ,seen through a telescope he looks like ,fig4 #ec1 though much smaller4 ,illustration3 ,,fig4 #ec4--,,mars ,,as ,,seen ,,through ,a ,,telescope4 ,but ,mars cannot always be seen1 for sometimes he disappears for a couple of years1 but when he finally does return he is a good planet1 for he stays a long time1 and you cannot mistake him1 for he will shine ruddy and bright with never a merry twinkle4 ,mars is #ada millions of miles from the sun4 ,his diameter is #d1bjj miles4 ,his day is #bd of our hours long4 ,his year is #fhg of our days long4 ,seeing ,venus4--,venus is so much brighter than any of the other stars or planets that you will know her the instant you see her4 ,indeed1 when ,venus is the brightest and the ,sun is far enough away from her1 she can often be seen with the naked eye in the daytime if the sky is clear4 ,three views of the phases of ,venus are shown in ,fig4 #ed4 ,illustration3 ,,fig4 #ed4--,,three ,,views ,,of ,,venus4 ,to see ,venus you must look for her early in the morning in the east before the ,sun is up1 or in the evening in the west just after the ,sun has gone down4 ,this is the reason ,venus is sometimes called an evening star and sometimes a morning star4 ,venus goes through phases like ,mercury and our ,moon1 but these cannot be seen with the naked eye4 ,when ,venus and the ,sun get too close together she cannot be seen1 for the light of the ,sun is so powerful that her reflected light is dimmed by it4 ,venus is a bright straw color and she is a beautiful object in the sky when visible1 but there are weeks at a time when she cannot be seen1 by reason of the ,sun outshining her when she is between us and the ,sun or on the other side of the ,sun4 ,the day and the year of ,venus are1 like ,mercury1 probably equal1 and hence one side of ,venus is always turned toward the ,sun and basks in its light and heat1 while the other side is turned away from the ,sun and is doomed forever to cold and darkness4 ,venus is #fg millions of miles from the ,sun4 ,her diameter is #g1gjj miles4 ,her day is #bbe of our days long4 ,her year is #bbe of our days long4 ,our ,earth4--,the ,earth is the third planet in distance from our ,sun1 and although it is small compared with some of the others it is so important to us that it will be described in a separate chapter4 ,fig4 #ee shows a view of the ,earth as she would be seen from the ,moon4 ,illustration3 ,,fig4 #ee4--,,the ,,earth4 ,illustration3 ,,fig4 #ef4--;,,jupiter4 ,the ,earth is #ic millions of miles from the ,sun4 ,her diameter is #g1ibj miles4 ,her day is #bd hours long4 ,her year is #cfe days long4 ,seeing ,jupiter4--,jupiter1 the largest planet which revolves round our ,sun1 is fifth in distance from him4 ,he is not as bright as ,venus1 but he is brighter than any of the fixed stars1 and by his brightness and silvery color he is quite easy to recognize4 ,this great planet seems not to have cooled down yet into a nice world like our own ,earth or someone's else ,mars1 but rather he is a ball surrounded by clouds of hot vapor4 ,still he is not hot enough to give out any light himself1 but like the rest of the planets he shines by the reflected light of the ,sun4 ,fig4 #ef is a view of ,jupiter as seen through a telescope2 one of the moons1 and its shadow on the planet1 is shown4 ,jupiter is crossed with several bands and he has nine moons to light up his great surface on a dark night1 but neither his belts nor his moons can be seen without a glass4 ,jupiter is #dhc millions of miles from the ,sun4 ,his diameter is #hg1jjj miles4 ,his day is about #aj of our hours long4 ,his year is almost #ab of our years long4 ,illustration3 ,,fig4 #eg4--,,saturn4 ,seeing ,saturn4--,it is not quite as easy to single out ,saturn with the naked eye1 for his light is just about as bright as ,capella in the constellation of ,auriga1 or any of the other first magnitude stars4 ,this disadvantage is offset by the fact that when he rises at sunset he can be seen during the whole night1 so that you will not only have plenty of time in which to find him1 but to observe him as well4 ,again1 ,saturn may be seen any clear night during the winter months until the year #aibj4 ,like the ,earth1 ,saturn is believed to have a more or less solid core1 but hotter and with layers of gas around him4 ,it is the sixth planet from the ,sun1 and with his beautiful rings1 which are formed of millions of little pieces--each a moon in itself--and with his ten large moons1 when seen through a telescope he is far and away the mightiest sight in the whole sky at night4 ,he and his wonderful rings are shown in ,fig4 #eg4 ,saturn is #hhf millions of miles from the ,sun4 ,his diameter is #gc1jjj miles4 ,his day is #aj of our hours long4 ,his year is #bi of our years long4 ,seeing ,uranus4--,if you have sharp eyes and will look for ,uranus in the spring and summer months1 you should be able to see him4 ,he has a pale green color1 and on a clear moonless night is visible to a good eye4 ,illustration3 ,,fig4 #eh4--,,uranus4 ,illustration3 ,,fig4 #ei4--,,neptune4 ,uranus is the planet star from the ,sun and before ,herschel discovered him with his homemade telescope astronomers frequently mistook him for a fixed star4 ,as seen through a large telescope ,uranus shows some indistinct markings4 ,uranus is #a1ghj millions of miles from the ,sun4 ,his diameter is #cb1jjj miles4 ,his day is thought to be #aa hours long4 ,his year is #hd of our years long4 ,neptune4--,neptune is so far away from the ,sun he cannot be seen with the naked eye1 but he can be easily seen with a good opera glass4 ,he is attended by one moon4 ,he is simply a disk of light when seen through a big telescope1 as shown in ,fig4 #ei4 ,neptune is #b1gij millions of miles from the ,sun4 ,his diameter is #cf1jjj miles4 ,his day is unknown4 ,his year is #afe of our years long4 ,the ,asteroids4--,the ,asteroids are a group of small planets moving around the ,sun in orbits between the ,earth and ,mars and1 hence1 at times these little bodies come very close to us4 ,the group occupies a place in the sky where we should expect to find a single large planet4 ,illustration3 ,,fig4 #fj4--,,marbles ,,on ,,top ,,of ,,table4 ,but when the planets were made1 ,jupiter1 with his great bulk pulled the soft pieces apart of which a planet would have been formed1 and instead of one planet of respectable size there are hundreds of little planets ranging anywhere from #aj miles to #ejj miles in diameter4 ,one of these small planets is called ,vesta1 and although she is only #bdj miles in diameter she may be seen on certain occasions with the naked eye4 ,positions of the ,planets ,round the ,sun4--,it was mentioned in the beginning of this chapter that all of the planets lay not far from one plane1 and that the ,sun's equator is nearly in this plane4 ,now let us see just what this means4 ,illustration3 ,,fig4 #fa4--,,top ,,view ,,of ,,solar ,,system4 ,suppose we lay eight marbles around a large marble placed on top of a table and in the center4 ,this means that all the marbles lie in the same plane which is the top of the table1 as shown in ,fig4 #fj4 ,the planets are all arranged round the ,sun1 as shown in ,fig4 #fa1 just the same as if they were all placed on a big1 level board or table top4 ,if we draw a picture of the plane view of the planets 7,fig4 #fj7 and the top view of the planets 7,fig4 #fa7 together1 we shall have a picture of the solar system1 as the ,sun and all of his planets are called1 as shown in ,fig #fb4 ,from these pictures you will see that the planets are not arranged1 in distance from the ,sun1 in order of size4 ,illustration3 ,,fig4 #fb4--,,solar ,,system ,,in ,,perspective4 ,to remember the arrangement of these planets in their relation to the ,sun commit to memory this simple sentence3 ,men ,very ,early ,made ,jars ,serve ,useful ,needs4 ,as the first letter of each of the above words is the same as the first letter of a planet1 you will be able to instantly recall the proper place of any one of them4 ,illustration3 ,,fig4 #fc4--;,,egg ,,shell ,,on ,,plate4 ,how the ,planets ,are ,held in ,space4--,if you will take an ordinary dinner plate and half an eggshell1 and give the eggshell a slight spin on the rim of the plate--the rim should be slightly moistened--you will find that by tilting the plate a trifle the eggshell will revolve in two directions2 first1 it will spin round on its own axis1 and second1 it will travel round the rim of the plate1 which we will call its orbit1 as shown in ,fig4 #fc4 ,this double motion of the eggshell is exactly like the double motion of a planet--each one turns on his own axis and each travels round the ,sun in its own orbit2 moreover1 all the planets travel round the ,sun in the same direction1 the nearest planets taking the shortest time to complete the circle or orbit1 while those farthest away take the longest time to go round their orbits just as we might expect them to do4 ,in the beginning of things the planets were a part of the ,sun1 as we shall see further on1 and when they were thrown off by him they spun round their own axes1 and they continued to spin round their axes just as a ball continues to do so after it has left the pitcher's hand4 ,the tendency to fly off at a tangent which every particle of a rotating body feels is called centrifugal force4 ,now1 no one knows what centrifugal force is1 but how it acts is very well known1 and you can find out for yourself by making the following experiment4 ,illustration3 ,,fig4 #fd4--;,,boy ,,throwing ,,stone ,,to ,,illustrate ,,centrifugal ,,force4 ,take a stone and tie one end of a string to it2 now swing the stone round in a circle2 if the string should break1 or you should let it go accidentally 7on purpose7 the stone will shoot off at a tangent1 that is in a line away from the circle in which it was swinging1 as shown in ,fig4 #fd4 ,this is just what made the planets1 one after another1 separate from the ,sun1 but they could not get very far away1 for another force which is not only in the ,sun but in every particle of matter in the universe1 pulled them back toward the ,sun1 just as it pulls a ball when thrown to the ,earth1 and this force is called gravitation4 ,so the centrifugal force keeps them spinning round on their axes and flying round in their orbits about the ,sun4 ,if it had not been for the attractive force of gravitation of the ,sun and the planets1 the planets would have kept right on going out into space and left the ,sun to shift for itself forever after4 ,as it is they whirl round the ,sun1 never able to get any farther from him and yet never getting any nearer to him1 for the centrifugal force tends to make them fly out and away and the force of gravitation tends to pull them back to the ,sun4 ,the result is that these two great opposing forces exactly offset or balance each other1 and the planets are held in their orbits just as securely as the stone is held out by the force the boy exerts to move it1 and in by the string he holds in his hand4 ,this balancing of opposed forces was nicely shown some years ago by ,sir ,robert ,ball1 the great ,english astronomer1 at one of his lectures in the ,royal ,institution of ,london1 and ,i reproduce it here4 ,to the ceiling over his lecture table he had fastened a thin wire1 the lower end of which was secured to a hollow iron ball4 ,when the ball was pulled aside1 it would swing like a great pendulum1 forth and back1 in a plane1 as shown in ,fig4 #fe4 ,illustration3 ,,fig4 #fe4--;,,iron ,,ball ,,pendulum ,,swinging ,,in ,,straight ,,line4 ,illustration3 ,,fig4 #ff4--;,,iron ,,ball ,,pendulum ,,swinging ,,in ,,curved ,,line4 ,but when a powerful magnet was placed on the table and the ball was set swinging in a plane as before1 just as it came close to the end of the magnet the latter pulled the ball with its mighty force toward it1 and so changed its course1 but the ball1 instead of being attracted directly to it1 swung in a graceful curve around it1 as shown in ,fig4 #ff4 ,this is precisely the case of the planets swinging round the ,sun1 and shows very nicely the balanced forces of the ,sun and the planets and why the planets stick to their orbits4 ,why the ,planets ,do ,not ,stop ,spinning4--,now you may ask why the planets do not stop turning on their axes and revolving in their orbits round the ,sun4 ,and the answer is because there is nothing to stop them4 ,if you spin a top on a plate it may keep going for a long time1 but it will finally die down and stop4 ,this is because there are other forces which oppose its centrifugal force4 ,the forces a spinning top has to overcome are friction between the point of its spindle and the plate1 and the resistance between the surface of the spinning top and the air pressing on its sides1 and the friction and the air resistance together soon use up the energy stored in the top and which makes it spin4 ,but if you could spin and throw a top far enough away from the ,earth so that it would not meet with friction or resistance of any kind1 it would go on spinning forever just like the planets4 ,how to ,plot the ,position of a ,planet4--,one of the tests which a ,boy ,scout must pass in order to obtain a merit badge for starcraft is to 8plot on at least two nights per month for six months the positions of all naked eye planets between sundown and one hour thereafter4 ,the plot of each planet shall contain at least three fixed stars with their names and designations1 colors of planets and stars to be recorded by him40 ,now1 by looking at your almanac under the head of ,morning and ,evening ,stars you will find all the planets which are listed as ,evening ,stars1 together with the dates when they can best be seen4 ,from your almanac for #aiae you will learn that ,mercury is an evening star1 and can be seen about ,feb4 #e1 ,may #ca and ,september #bg in the west1 just after sunset2 that ,venus will be an evening star from ,september #ab for the rest of the year2 that ,jupiter will be an evening star until ,february #bd2 after that a morning star until ,september #ag1 and then an evening star for the rest of the year1 and that ,saturn will be an evening star until ,june #bh4 ,the first thing to do is to find what constellation is on your meridian at #i ,p4 ,m4 for the month that the planet you wish to plot is to be seen4 ,this you can do by looking at the map of the stars shown in ,fig4 #fg4 ,you can see any of the stars or constellations on your meridian by looking for them at #i o'clock ,p4 ,m4 on the months marked above them4 ,this done1 consult your almanac and find out what time the ,sun sets on the day that the planet you are looking for can be seen4 ,as an example let's take ,mercury1 which the almanac says is an evening star about ,february #e1 and which can be seen in the west just after sunset4 ,the almanac will also tell you that the ,sun sets on ,february #e at #e o'clock4 ,illustration3 ,,fig4 #fg4--,,map ,,of ,,stars ,,on ,,sun',s ,,path4 ,the star map 7,fig4 #fg7 will show you that the constellation of ,gemini1 the ,twins1 is one which can be seen in ,february on your meridian at #i o'clock at night1 and you know that ,mercury can be seen close to the western horizon from #c to #d hours earlier4 ,since ,gemini1 the ,twins1 is on the meridian at #i o'clock1 ,taurus1 the ,bull1 which is the next constellation to it1 will be on the meridian at #g o'clock1 and ,aries1 the ,ram1 will be on the meridian at #e o'clock4 ,now the next constellation to the west of ,aries1 the ,ram1 is ,pisces1 the ,fishes1 and the next one to ,pisces1 the ,fishes1 is ,aquarius1 the ,water ,bearer1 and as this constellation sets about an hour after the ,sun1 it is in this constellation that you will find ,mercury in the early ,february evenings4 ,illustration3 ,,fig4 #fh4--;,,diagram ,,of ,,position ,,of ,,constellations4 ,the diagram 7,fig4 #fh7 shows how it is that when ,aries is on the meridian at #e o'clock in the evenings of ,february1 ,gemini will be rising in the east1 and ,aquarius1 with ,mercury in it1 will be getting ready to set in the west4 ,you can find all the other planets in the same way1 but it is much easier to find them in the sky than it is to try and imagine their positions after reading how it is done4 ,you should1 though1 by all means1 read the chapter on ,the ,stars of the ,zodiac before you try to plot a planet1 for there is much useful information in it which you ought to know4 ,illustration3 ,,no4 ,,of ,,chart--#c ,,date--,,feb #e ,,time--#e-f ,p4,m4 ,,name ,,of ,,planet--,,mercury ,,name ,,of ,,nearest ,,stars ,,color ,,of ,,planet--,,pale ,,ash ,,phi ,,ophincus ,,william ,,brown ,,formalhaut ,,in ,,southern ,,fish ,,color ,,of ,,stars ,,alpha ,,beta1 ,,white ,,formalhaut1 ,,straw ,,fig4 #fi4--,,plotting ,,position ,,of ,,planet4 ,to plot the position of a planet1 take a sheet of stiff paper or cardboard about #h inches square and divide it into a square #f inches on the side1 as shown in ,fig4 #fi4 ,this will leave a margin of #a inch on both sides1 inch on top and #a inches at the bottom of your paper4 ,fasten the paper to your starboard1 described in ,chapter ,,ii1 and go forth with it and your acetylene or flash lamp and find your planet4 ,having found it1 mark with a pencil in the squares on your ruled paper the positions of three of the nearest fixed stars which are shown in the star chart of ,fig4 #fg4 ,now mark the position of the planet as you see it on your chart by making a little circle and your outdoor observation is ended4 ,once inside1 mark down the chart number1 the date and the time you made the observation2 also the names and colors of the stars and the planet1 and finish the record by signing your name4 ,should any of the other planets be visible at the time of your observation you will1 of course1 have to plot two charts1 unless the planets are very near each other4 ,,chapter ,v ,,mother ,,earth1 ,,old ,,adam',s ,,planet ,the ,earth in the ,making4--,the ,earth on which we live and find so much that is interesting was once a part of our ,sun just as the other planets were4 ,when the ,sun was being made of star stuff great quantities of gases were set into mighty whirls1 and when these acquired enough force they shot off into space like so many cannon balls1 and they are still a-whirling4 ,but these new-born planets could only get a certain distance away from the ,sun1 as we have learned1 for the force of his attraction offset the force of their motion with the result that they are still held in space around him4 ,one of these whirling bodies was the ,earth1 and when it had comfortably settled in its orbit and slowed down a bit it began to cool off and a crust was formed on its liquid surface1 just as ice is formed when water is frozen4 ,then some of the gases condensed into water and others became air and when the ,earth had cooled down still further some millions of years afterward it became a more or less suitable place for human beings to live on4 ,while the ,earth has cooled off until it is possible for us to live comfortably on its crust1 it is still warm outside and very hot inside4 ,this is proved by volcanoes which throw out white hot lava and gases when they are in eruption4 ,if it had not been for the light and heat of the ,sun in the past ages there never could have been any kind of life on the ,earth4 ,the ,earth is just as dependent on the ,sun now as it was in the past1 and if he should fail to shine on our world for even a little time everything would die4 ,fig4 #gj is a cross section of the ,earth4 ,to ,prove the ,earth is ,round4--,every boy knows that the ,earth is round1 but the wisest of men did not know it for certain until about #djj years ago1 when one of ,magellan's ships made a complete voyage round the world and returned to the place she started from4 ,illustration3 ,,fig4 #gj4--;,,cross ,,section ,,of ,,the ,,earth4 7#a7 ,one of the easy ways to show that the earth is round1 or at least that the surface of the earth is curved1 as shown in ,fig4 #ga1 is to watch a ship as she sails out to sea4 ,all of the ship--hull1 sails and smokestack1 if she has one--can be seen until she sails over the horizon1 and then her hull1 which is the largest part of her1 is lost to view1 then her sails and stack1 and finally only the tops of her masts can be seen4 ,it is a pretty good sign that the ,earth is a ball4 ,illustration3 ,,fig4 #ga4--,,sails ,,of ,,ship ,,can ,,be ,,seen ,,after ,,hull ,,has ,,disappeared4 7#b7 ,a very pleasant way to prove the ,earth is a ball is to take passage on a ship that makes a round-the-world cruise4 ,if you leave ,new ,york and keep sailing east all the time you will finally land at ,san ,francisco2 keep on going east by rail and you will find yourself back in dear old ,new ,york1 where you started from4 ,see ,fig4 #gb4 ,to ,prove the ,earth ,turns on ,its ,axis4--7#a7 ,having proved that the ,earth is round1 the next thing to do is to prove that it turns about on its axis4 7#a7 ,the best known experiment for showing that the ,earth really turns on its axis was made by ,foucault 7pronounced ,foo-ko71 a ,french philosopher1 in #ahea1 who used a pendulum for the purpose4 ,illustration3 ,,fig4 #gb4--,,sailing ,,round ,,the ,,earth4 ,in the top of a great dome in a building in ,paris1 called the ,panthon1 ,foucault hung a large metal ball by means of a wire about #aej feet long4 ,on the floor he made a mark1 exactly under the ball1 running due north and south4 ,then drawing back the ball1 he let it go1 when it swung directly over the line4 ,the heavy pendulum1 which after being started swung for hours1 seemed to move away from the line in the direction of the hands of a watch4 ,this showed that the floor of the ,panthon was really skewing around under the swinging pendulum4 ,this is easily explained as due to the rotation of the earth because the northern edge of the floor was nearer the axis of the earth than the southern edge and therefore was carried more slowly eastward4 7#b7 ,a much simpler way to show the turning of the ,earth on its axis1 though this experiment only proves that either the ,earth or the whole sky turns1 is to make a photograph of the ,north ,star and the stars in its neighborhood1 as explained in ,chapter ,,xii4 ,during the time the sensitive plate is being exposed the camera will be carried round by the ,earth turning on its axis and the fixed stars will leave bright trails on the plate in arcs of circles4 ,the ,earth ,turning on ,its ,axis ,makes ,day and ,night4--,the ,earth1 in turning round on its axis once every #bd hours1 receives the light of the ,sun on half of its surface at a time1 making the day1 while the other half is in the shadow1 which makes the night4 ,illustration3 ,,fig4 #gc4--,,the ,,earth ,,moves ,,away ,,from ,,the ,,swinging ,,pendulum4 ,if the equator of the earth was in a plane with the ,sun1 as shown in ,pig4 #gd1 it is easy to see that the days and nights all over the world would be of the same length1 that is1 each would be #ab hours long4 ,instead1 the ,earth is tilted a little1 as shown in ,fig4 #ge--to be exact1 its axis is tilted #bc degrees out of the perpendicular and this makes the day and the night at the equator each #ab hours long and the day and the night at the north and south poles each six months long4 ,the circle round the ,sky which is in a plane with the ,sun is called the ecliptic4 ,the ,sun seems to follow a path round the ,earth in this plane1 and this is called the path of the ,sun4 ,to ,show ,that the ,earth ,travels ,round the ,sun4--,when we look at the ,sun and the stars it is hard to believe that they are standing still and that it is the ,earth which is whirling round on its own axis and also round the ,sun4 ,illustration3 ,,fig4 #gd4--;,,if ,,the ,,earth',s ,,equator ,,were ,,in ,a ,,line ,,with ,,the ,,sun4 ,illustration3 ,,fig4 #ge4--,,the ,,earth ,,tilted ,,on ,,its ,,axis4 ,we have given a couple of experiments to show that the ,earth turns on its own axis1 and here is one to make it clear how the ,earth travels in a great circle1 or rather ellipse1 round the ,sun and gives us our year4 ,further1 the ,earth's axis being tilted away from the axis of the orbit1 its movement round the ,sun causes the north pole to be turned toward the ,sun half of the time1 and then the south pole to be turned toward the ,sun an equal length of time1 which gives each of them a day and a night that is six months long4 ,illustration3 ,,fig4 #gf4--,,light ,,in ,,room ,,to ,,represent ,,sun4 ,in the center of a large room set a light so that it will be about as high as your eyes4 ,let this light represent the ,sun2 you must play now that you are the ,earth1 and think of the pictures on the wall as being the stars fixed in the sky away off in space4 ,now walk in a circle around the light toward the right and facing the light all the time4 ,as you move around the light you will see that it seems to move in the opposite direction and that it seems to move past the pictures on the wall4 ,the experiment is shown in ,fig4 #gf4 ,this1 then1 is exactly what happens when we look at the ,sun and the stars4 ,the ,earth moves round the ,sun in a circle1 nearly1 and since the ,sun is so much closer to us than any of the other fixed stars the ,sun apparently moves by the stars1 because the ,earth changes its position relative to it and the stars4 ,the ,earth ,turning ,round the ,sun ,makes the ,seasons4--,we have seen how the days and nights would be equal all over the world if the equator of the ,earth was in a plane with the ,sun1 but since the ,earth is tilted the days and nights are unequal except twice a year1 and this is when the places where the ecliptic and the equator cross each other are facing the ,sun4 ,illustration3 ,,fig4 #gg--,,top ,,spring ,,on ,,plate4 ,again1 if the ,earth's equator was always in a plane with the ,sun the day would be just as long as the night all through the year and there would be no seasons4 ,but the ,earth having its axis tilted1 and which is always set in the same direction1 together with the ,earth speeding in a circle around the ,sun1 causes some curious things to happen and the seasons are one of them4 ,to make clearer the reason the axis of the ,earth always stays in one position take a top and give it a good spin4 ,the top1 of course1 turns round its axis very fast1 and this is like the ,earth turning round its axis every #bd hours4 ,now1 if you place the blunt end of a pencil on the upper axis of the spinning top1 as shown in ,fig4 #gg1 and try to tilt it in some other direction than that it took when it began to spin1 you will find it rather a hard thing to do4 ,in other words1 once a body is rapidly turning on its own axis it very strongly tends to keep its axis pointing in the same direction4 ,this rule also applies to the ,earth1 for having been tilted at an angle when it was thrown off by the ,sun in the making1 no other forces have ever been able to change the position of its axis to any great extent1 though1 the ,earth spins easily on its axis and also revolves round the ,sun4 ,to understand how the seasons are made you must first have clearly in mind the positions of the tilted ,earth in different parts of its orbit round the ,sun4 ,the things needed for this experiment are a nice round apple1 a candle1 a piece of string1 a safety-pin and a knitting needle4 ,illustration3 ,,fig4 #gh4--;,,circle ,,around ,,candle ,,marked ,,with ,,seasons4 ,place the candle in the center of a table and call it the ,sun2 draw a circle a foot in diameter on the table top and around the candle with a bit of chalk4 ,mark one side ,september #bb2 at the next quarter of the circle mark ,december #ba2 directly opposite the ,september mark chalk in ,march #ba1 and finally between ,march and ,september mark ,june #ba1 all of which is shown in ,fig4 #gh4 ,push the knitting needle through the center of the apple1 call the apple the ,earth and call one end of the knitting needle the north pole and the other end the south pole4 ,fasten the safety-pin through the skin of the apple and tie the string to the pin so that when the string is tied to a tack in the ceiling or some one is holding it directly over the candle the knitting needle of the apple will be tilted to the perpendicular1 as shown in ,fig4 #gi4 ,illustration3 ,,fig4 #gi4--;,,apple ,,to ,,represent ,,earth ,,suspended ,,in ,,air4 ,illustration3 ,,fig4 #hj4--,,position ,,of ,,the ,,earth ,,and ,,sun ,,in ,,autumn4 ,illustration3 ,,fig4 #ha4--,,position ,,of ,,the ,,earth ,,and ,,sun ,,in ,,winter4 ,illustration3 ,,fig4 #hb4--,,position ,,of ,,the ,,earth ,,and ,,sun ,,in ,,spring4 ,illustration3 ,,fig4 #hc4--,,position ,,of ,,the ,,earth ,,and ,,sun ,,in ,,summer4 ,now grasp the top of the needle1 which is the north pole1 with the left hand and hold the apple away from the candle1 as shown in ,fig4 #hj4 ,this is the position of the earth to the ,sun on ,september #bb1 when the ,sun passes directly over the ,earth's equator1 and for us autumn is at hand4 ,now pull the apple by its north pole toward you and around one quarter of the circle chalked on the table1 as shown in ,fig4 #ha1 which is the position of the ,earth to the ,sun on ,december #ba4 ,you will see that the north pole is away from the light and heat and hence it is dark and winter there2 but the south pole on the other end is getting plenty of light and heat and it is both day and summer there4 ,this marks the beginning of our winter4 ,illustration3 ,,fig4 #hd4--;,,cycle ,,of ,,seasons4 ,push the apple by its north pole--always being careful to keep the knitting needle tilted in the same position--around another quarter of a circle and this is where the ,earth is in its orbit1 and its position to the ,sun on about ,march #ba4 ,once again the ,sun is over the ,earth's equator and all parts or our world are then lighted and heated twelve hours out of the twenty-four1 and we have the beginning of spring4 ,see ,fig4 #hb4 ,again push the apple around another quarter circle and ,june #ba is reached4 ,this time you will find the north pole is turned toward the ,sun and this time it gets the light and heat for six months1 while the south pole is away from the ,sun and takes its turn of six months of night and winter4 ,to us1 however1 it is the beginning of summer4 ,fig4 #hc shows the position of the ,earth to the ,sun at this time4 ,pull the apple one more quarter of the circle round the candle and you will have completed its orbit just as the ,earth swings round the ,sun in #cfe days4 ,the seasons are more clearly shown in ,fig4 #hd4 ,the ,north ,pole4--,the north pole is not only one of the ends of the axis round which the ,earth turns but close to it is the north magnetic pole as well4 ,by magnetic we mean that the ,earth behaves like a steel bar that has been magnetized4 ,a steel bar magnet like that shown in ,fig4 #he is strongest at its ends4 ,one end is positively magnetized1 and we call this end its north pole1 and the other end is negatively magnetized1 and we call this end its south pole4 ,magnetic lines of force stream from the south pole through the steel bar and reaching the north pole they stream through the air to the south pole1 as shown by the curved lines1 thus forming a magnetic circuit1 just as two wires joined together may form an electric circuit4 ,if we place a compass needle near the steel bar magnet the needle will turn in the same direction as the magnetic lines of force are flowing1 and it will1 therefore1 point to the north and to the south poles of the magnet4 ,now the ,earth is a great magnet with a positive pole1 which we call the north pole at one end of its axis1 and a negative pole1 which we call the south pole1 at the other end of its axis1 as shown in ,fig4 #hf4 ,illustration3 ,,fig4 #he4--,,lines ,,of ,,force ,,through ,,and ,,around ,a ,,magnet4 ,illustration3 ,,fig4 #hf4--,,lines ,,of ,,force ,,around ,,the ,,earth4 ,like a bar magnet1 magnetic lines of force stream all over the ,earth's surface from the north pole to the south pole1 and a compass needle placed anywhere on the ,earth will swing round until it is in the same direction as the lines of magnetic force4 ,illustration3 ,,fig4 #hg4--,,watch ,,spring--,,needle ,,for ,,compass4 ,illustration3 ,,fig4 #hh4--;,,compass ,,complete4 ,how to ,make a ,simple ,compass4--,take a piece of watch spring about #c inches long and straighten it4 ,heat the middle red-hot and let it cool slowly1 when the temper will be taken out of it at this point4 ,place a center punch in the middle of the spring and strike it a sharp blow with a hammer2 this will make a little dent in it4 ,bend it as shown in ,fig4 #hg4 ,to magnetize the needle rub one end on the north pole and the other end on the south pole of a steel magnet4 ,stick a sewing needle into a large cork and lay the magnetized needle on it1 when it will point north and south1 as shown in ,fig4 #hh4 ,boxing the ,compass4--,there are two kinds of compasses in general use1 though both kinds use a magnetized needle4 ,the first kind is the ordinary pocket compass1 with either a pull-off cover or one of the watch-case pattern4 ,in this kind of a compass the magnetic needle is fitted with a jeweled center which swings on a steel needle2 the dial is fixed in the case and is marked with the cardinal points1 that is with the chief points of a compass4 ,fig4 #hi shows a pocket watch-case compass4 ,illustration3 ,,fig4 #hi4--,,pocket ,,watch-,,case ,,compass4 ,illustration3 ,,fig4 #ij4--;,,dial ,,of ,,mariner',s ,,compass4 ,in the mariner's compass1 which is used at sea1 the compass card and the magnetic needle are fastened together4 ,the card is made of a circular sheet of mica and the points of the compass1 which are called rhumbs1 are marked on the edge4 ,the needle and card float in a bowl of mercury4 ,the card is marked with #cb rays1 forming a many-pointed star1 and each of these points has a name1 the names of the four cardinal points being north1 east1 south and west4 ,to know all of the points by heart and be able to name them1 beginning with the north and going round the card to the north again1 is what sailors call boxing the compass4 ,see ,fig4 #ij4 ,points on ,names of ,points ,compass ,card ,n ,north ,n b,e ,north by east ,,nne ,north1 northeast ,,ne b,n ,northeast by north ,,ne ,northeast ,,ne b,e ,northeast by east ,,ene ,east1 northeast ,e b,n ,east by north ,e ,east ,e b,s ,east by south ,,ese ,east1 southeast ,,se b,e ,southeast by east ,,se ,southeast ,,se b,s ,southeast by south ,,sse ,south1 southeast ,s b,e ,south by east ,s ,south ,s b,w ,south by west ,,ssw ,south1 southwest ,,sw b,s ,southwest by south ,,sw ,southwest ,,sw b,w ,southwest by west ,,wsw ,west1 southwest ,w b,s ,west by south ,w ,west ,w b,n ,west by north ,,wnw ,west1 northwest ,,nw b,w ,northwest by west ,,nw ,northwest ,,nw b,n ,northwest by north ,,nnw ,north1 northwest ,n b,w ,north by west ,n ,north ,,dial ,,of ,a ,,mariner',s ,,compass ,how to ,make a ,simple ,dipping ,needle4--,when a compass needle is pivoted so that it can swing up and down1 that is1 to and away from the earth1 it is called a dipping needle4 ,such a needle will dip toward the nearest pole of the earth4 ,at the magnetic equator there is no dip1 that is1 the needle will stand parallel with the ,earth's surface4 ,illustration3 ,,fig4 #ia4--,,needle ,,for ,,dipping ,,needle4 ,at the north magnetic pole the needle will stand straight up and down in a line with the axis of the ,earth4 ,the dip1 therefore1 of the needle at any place on the ,earth's surface is just about that of the latitude of the place where it is used4 ,dipping needles are also used by miners for finding iron ores4 ,illustration3 ,,fig4 #ib4--;,,dipping ,,needle ,,complete4 ,to make a dipping needle1 slip a small cork over a knitting needle and push a sewing needle through the cork at right angles to the knitting needle1 as shown in ,fig4 #ia4 ,now lay the sewing needle with its ends on the edges of two tumblers1 and see that the knitting needle is perfectly balanced4 ,this done1 magnetize the knitting needle by rubbing one end on the north pole of a steel magnet and the other end on the south pole of the magnet4 ,make a little wood stand as shown in ,fig4 #ib and place the ends of the sewing needle on the wood supports4 ,illustration3 ,,fig4 #ic4--,,protractor ,,showing ,,degrees4 ,illustration3 ,,fig4 #id4--;,,earth ,,surface ,,divided ,,into ,,degrees4 ,the latitude running through the middle of the ,united ,states is about #dj degrees north of the equator and if you live in this latitude the dip of your needle will be about #dj degrees from the horizontal4 ,illustration3 ,,fig4 #ie4--,,protractor ,,set ,,by ,,dipping ,,needle ,,showing ,,latitude4 ,how to ,find ,latitude4--,the latitude of a place on the ,earth's surface is its distance north or south of the equator4 ,this distance is usually measured in degrees of a circle1 instead of in miles4 ,the equator is called #j 7zero7 degrees1 and the north and south poles are #ij degrees from the equator1 as shown in ,fig4 #ic4 ,if you are in ,philadelphia1 ,pennsylvania1 or ,quincy1 ,illinois1 or ,tehama1 ,california1 you are in latitude #dj degrees4 ,if you are in ,bangor1 ,maine1 ,st4 ,paul1 ,minnesota1 or ,portland1 ,oregon1 you are in latitude #de degrees1 or just halfway between the north pole and the equator1 as ,fig4 #id shows4 7#a7 ,an easy way to find roughly the latitude of a place1 that is1 its distance from the equator1 is to use a dipping needle and a protractor4 ,to make a protractor cut out a semi-circle of stiff1 white cardboard1 just the size shown in ,fig4 #ic1 and mark the figures on the edge and draw lines from the edge to the center point exactly as in the picture4 ,illustration3 ,,fig4 #if4--,,two ,,sticks ,,screwed ,,together4 ,illustration3 ,,fig4 #ig4--,,two ,,sticks ,,across ,,bucket ,,of ,,water4 ,now place your dipping needle on a level board or table and set the center of your cardboard protractor in line and on a level with the axis of the needle1 as shown in ,fig4 #ie4 ,whatever line on the protractor the dip of the needle takes the degree marked on the edge of the protractor will be the magnetic latitude you are in4 7#b7 ,a way to obtain true latitude is to take two smooth pieces of wood1 about #a foot long and inch thick1 and hinge them together at one end with a screw1 as in ,fig4 #if4 ,now set a bucket out-of-doors in an open space from which the ,north ,star may be seen1 fill the bucket with water and level it up until the water is parallel with the rim all the way round4 ,when night falls find the ,north ,star and set your sticks across the rim1 as shown in ,fig4 #ig4 ,raise one of the sticks and sight it until it points straight at the ,north ,star1 and having done this you are through with the observation4 ,take the sticks into the house1 being very careful not to change their relative positions1 so that the angle they form can be measured with a protractor4 ,tack a piece of paper on your starboard and draw a straight horizontal line on it4 ,lay the stick that was on the bucket on the horizontal line1 and draw a line along the edge of the other stick with which you sighted the ,north ,star1 as in ,fig4 #ih4 ,now measure the distance1 in degrees1 between the two lines with your protractor and the number of degrees you get will be roughly the latitude4 ,shooting the ,sun4--,another and very exact way to find the latitude1 and which is also used to help find longitude when at sea1 is by means of an instrument known as a sextant1 so called from the fact that it is formed of a sixth part of a circle4 ,illustration3 ,,fig4 #ih4--,,protractor ,,and ,,sticks ,,on ,,drawing ,,paper4 ,it is made with a metal frame ,a and having the degrees marked on its curved edge ,b like a protractor4 ,on one end of a thin strip of metal1 or arm1 ,c 7see ,fig4 #ii71 a mirror1 ,d1 called an index mirror1 is rigidly fastened1 and right under the center of this mirror the arm ,c is hinged to the frame ,a4 ,the other end of this arm slides over the scale ,b4 ,to the left side of the frame also rigidly fastened is a second glass ,e called a horizon glass1 and half of which is clear and half silvered4 ,a telescope is also rigidly fastened to the frame ,a directly opposite but in a line with the horizon glass ,e4 ,now to find the latitude by taking the ,sun1 or as sailors sometimes call it1 shooting the ,sun1 in order to learn the position of the ship at sea1 the sextant is held in both hands firmly1 and the horizon which is sighted through the telescope is brought into view through the clear part of the horizon glass ,e4 ,the arm ,c1 carrying the index mirror ,d1 is now moved over the scale ,a until the light from the ,sun just as it crosses the meridian at noon is reflected by its polished surface into the silvered part of the horizon glass ,e1 and this reflects the sunlight into the telescope right in a line with the line of sight to the horizon4 ,this forms an angle of the two beams of light just as an angle is formed of the two sticks of wood in the pail experiment and the number of degrees the end of the arm ,c points to on the scale ,b is the latitude in degrees or the distance of the ship north or south of the equator4 ,illustration3 ,,fig4 #ii4--,,sextant ,,in ,,use4 ,,shooting ,,the ,,sun4 ,how ,longitude is ,found4--,to find the longitude at sea1 that is1 the position of a ship east or west of a given place1 is just as simple a matter as finding the latitude or its position north or south of the equator4 ,two instruments are used to find longitude1 and these are the sextant1 which has just been described1 and a very accurate clock1 called a chronometer 7pronounced chro-nom-e-ter74 ,as you know1 imaginary lines running from the north pole to the south pole are called meridians of longitude4 ,now the ,earth has been divided into #bd of these lines1 the zero meridian1 from which distances east and west are measured1 running through ,greenwich1 ,england4 ,there are #bd of these standard meridians and hence they are #ae degrees apart--since there are #cfj degrees in a circle--and they are #a hour apart--since there are #bd hours in a day1 and therefore #ae degrees equal #a hour4 7,see ,chapter ,x1 ,the ,time o' ,day47 ,now1 since it is #ab o'clock noon when the ,sun passes over any one of these standard meridians1 it will be #aa o'clock ,a4 ,m41 #ae degrees west of it1 and #a o'clock ,p4 ,m41 #ae degrees east of it1 and consequently there will be an hour's difference in the time1 either fast or slow1 for every #ae degrees1 depending on whether you count east or west from the noon meridian4 ,the purpose of a sextant in finding longitude on shipboard is to know when it is exactly noon by the ,sun1 and in this way the local time is found4 ,the purpose of a chronometer is to carry exact ,greenwich time1 and the difference between the local time found each day by taking the ,sun1 and ,greenwich time shown by the chronometer gives the distance in degrees the ship has traveled from ,greenwich4 ,by knowing the latitude and longitude of a ship the distance in miles north and south and east and west from any port can be figured out without much trouble4 ,the reason that a very accurate clock has to be carried is that a difference of a few seconds either too fast or too slow will affect the calculations just that much1 and this means that the ship will be thrown out of its calculated position by several miles4 ,to correct the observations with the sextant and the inaccuracy of the chronometer1 etc41 are a part of the business of the navigating officer1 and he is provided with tables and things to make this work as easy and certain as is possible4 ,how to ,know ,when ,you ,are at the ,north ,pole4--,if you should ever reach the north pole where overhead is north and every other direction is south how would you know it8 ,suppose you were standing on the exact top of the world during one of its long polar nights1 then the ,north ,star would be directly over your head and the ,big ,dipper and ,cassiopeia would serve to mark the passing of days as well as of nights1 that is1 if you were at the north pole in the wintertime4 ,illustration3 ,,fig4 #ajj4--,,shadows ,,at ,,the ,,north ,,pole4 ,but if you were there during a long ,arctic day1 that is1 in the good old summertime1 you could see the ,sun making a circle1 or seeming to1 once in #bd hours1 parallel to the horizon1 and never going higher or getting lower4 ,explorers use a sextant to find out when they are at the north pole1 and they sight the ,sun's height above the horizon at morning1 noon and night4 ,if the angle the ,sun makes with the horizon is the same every time he is observed1 the explorer knows he is standing on the very point round which the ,earth turns4 ,then he plants a stick in the snow and ice on the north pole1 hoists the ,american flag1 and hurries home as fast as dogs and ships and trains can carry him to tell about it4 ,if you ever reach the north pole you can know it1 too1 even though you haven't a sextant with you4 ,all you need to do1 when you think you are standing on the north pole1 is to notice the length of your shadow five or six times in #bd hours4 ,if the length of your shadow is exactly the same every time you look at it1 as shown in ,fig4 #ajj1 you are really and truly at the north pole4 ,difference ,between the ,true ,north ,pole and the ,magnetic ,north ,pole4--,the compass and dipping needle do not point to the true north pole1 for the magnetic north pole and the true north pole are not located at the same place4 ,the magnetic north pole was found by ,captain ,ross in #ahcb4 ,at that time the magnetic north pole was northwest of ,hudson's ,bay in about latitude #gj degrees north and longitude #if degrees and #de minutes west1 that is1 west of the zero meridian which runs through ,greenwich4 ,,chapter ,,vi ,,the ,,moon1 ,,the ,,earth',s ,,daughter ,how the ,moon ,was ,made4--,there was a time away back in the beginning of the planets when the ,earth did not have a ,moon4 ,two ideas among others have been worked out to account for the birth of the ,moon and these are somewhat alike1 for both agree that just as the ,earth was once a part of the ,sun and was separated from the ,sun and became a planet so the ,moon was once a part of the ,earth and was thrown off and became her daughter4 ,illustration3 ,,fig4 #aja4--,,moon ,,and ,,earth ,,joined ,,together ,,like ,a ,,dumbbell4 ,the first idea as to how the ,moon was made is that a smaller core was formed in the gaseous matter of the ,earth and that this core and the core of the ,earth1 which were at first joined together like a dumbbell1 as shown in ,fig4 #aja1 began to spread apart like a pair of balls fastened together with a piece of elastic when they are whirled rapidly round each other1 as shown in ,fig4 #ajb4 ,illustration3 ,,fig4 #ajb4--;,,balls ,,connected ,,with ,,an ,,elastic4 ,so1 too1 the high speed with which the ,earth turned on its axis when it was in the making caused the smaller part to slowly move away and it became the ,moon4 ,the second idea is like the first1 except that the ,earth is thought to have cooled down until it was a melted mass1 and it was then that a great upheaval took place in which a part1 one-eightieth as large as that of the world itself1 was torn out of its side and1 whirling away by centrifugal force1 the ,moon was born4 ,to throw off such a mighty part of its bulk as the ,moon1 it has been figured out that the ,earth must have made a complete turn on its axis every #b hours1 instead of one turn in #bd hours1 as it now does2 and it was while the ,earth was turning at this terrific rate of speed that the centrifugal force overcame the force of gravitation and tore the ,moon from the ,earth's side and formed a little world of its own4 ,illustration3 ,,fig4 #ajc4--,,map ,,showing ,,pacific ,,ocean4 ,it is believed by some astronomers that the ,moon was once that part of the ,earth which is now filled up by the waters of the ,pacific ,ocean and there are several reasons why this seems very likely4 ,first1 if the waters which form the ,pacific ,ocean were rolled into a big ball it would be just about the size of the ,moon2 second1 the space between the coasts of ,north and ,south ,america on the east1 and ,asia and ,australia on the west1 will be seen by referring to ,fig4 #ajc to be roughly circular in form2 third1 there is a marked likeness between the volcanoes in ,california1 in the ,hawaiian ,islands and in ,japan to those on the ,moon4 ,illustration3 ,,fig4 #ajd4--;,,imitating ,,the ,,volcanoes ,,in ,,the ,,moon4 ,it was1 doubtless1 at this long ago time that the great volcanoes of the ,moon1 as well as those of the coasts of and on the islands in the ,pacific ,ocean were made1 but what caused them can only be guessed at4 ,there are two ideas1 also1 to account for them2 one is that the pent-up gases inside the ,earth and the ,moon exploded and so threw up the volcanoes2 the other idea is that showers of gigantic melted masses fell on the surface of both the ,earth and ,moon and so caused them4 ,an experiment to show how the volcanoes might have been formed by showers of meteors can be made by covering the surface of your starboard with a layer of soft clay about #d inches thick1 and then throwing clay balls against it4 ,artificial volcanoes with craters and all will result4 ,compare your artificial volcanoes with ,fig4 #aje1 showing the real volcanoes on the ,moon1 and you will see they are quite alike4 ,illustration3 ,,fig4 #aje4--,,real ,,volcanoes4 ,the volcanoes of ,california1 ,japan and the ,hawaiian ,islands are1 many of them1 still active1 while those on the ,moon have long since become extinct4 ,this is easily accounted for1 since the mass of the ,moon is very small compared with that of the ,earth1 and hence1 the ,moon has cooled off more quickly than the ,earth4 ,the result is that while the ,earth is yet hot and teeming with life and activity1 the ,moon is cold1 and dead and silent4 ,seeing the ,moon ,with the ,naked ,eye4--,if you look at the full ,moon with the naked eye it will appear as a great1 silvery-bright disk1 and about the same size as the ,sun4 ,look again and you will see that some parts of it are much brighter than others1 while another and closer observation will show you that the light and shaded parts take on the expression of a man's face1 as shown in ,fig4 #ajf4 ,this is the famous ,man in the ,moon1 and once you make out the likeness you will never again be able to look the full ,moon in the face without seeing the man in it4 ,illustration3 ,,fig4 #ajf--,,naked ,,eye ,,drawing ,,of ,,full ,,moon4 ,when we look at the ,moon we always see the same side of it1 which will be readily understood when we come to the turning of the ,moon on its axis4 ,as the ,moon revolves about the ,earth1 you will see1 if you look toward the west at the right time of the month1 just at dusk1 a pale crescent of light1 and very soon after the ,sun sets it drops out of sight below the horizon4 ,a few nights later the ,moon will be seen1 over in the sky toward the east2 its crescent shape grown into the first quarter1 and the ,moon looks as if it was split in two4 ,as the nights go by the ,moon waxes until it is gibbous and finally the full ,moon--with the man in it--stands out round and clear and bright4 ,it is a good idea at this time1 that is1 when the ,moon is full1 to make a drawing of her face1 and the best time to do it is shortly after twilight1 for later in the evening the ,moon is so bright it is hard to see the details4 ,after this the ,moon begins to wane2 it again becomes gibbous2 then reaches its last quarter later only a crescent can be seen1 and she finally disappears4 ,at times when the crescent is bright the whole dark disk of the ,moon can be seen glowing dimly with a reddish1 copper color1 and this is called the old ,moon in the new ,moon's arms4 ,this copper-colored glow is the ,earth-shine on the ,moon1 that is1 the sunlight on the ,earth1 which is reflected to the ,moon and back again to us4 ,on one side of the ,moon you may be able to see a dark oval spot which is marked ,grimaldi on the maps of the ,moon4 ,grimaldi is a great plain1 having nearly #ad1jjj square miles in it1 with mountains flanking it on the sides4 ,this is another good eyesight test1 for it takes a mighty sharp eye to see it without a glass4 ,these and a dozen other interesting things on the ,moon can be seen without a telescope4 ,the ,motions of the ,moon4--,the ,moon turns round on its axis once every month and it also revolves round the ,earth once every month1 so that the ,moon's day and year are of the same length just like ,mercury and ,venus1 and this is the reason that one side of the ,moon is always turned toward the ,earth1 as you will see if you look at her through a glass4 ,illustration3 ,,fig4 #ajg4--,,the ,,experiment ,,showing ,,how ,,one ,,revolution ,,of ,,the ,,moon ,,round ,,the ,,earth ,,makes ,,it ,,turn ,,once ,,round ,,its ,,axis4 ,a simple experiment will show the cause of this3 ,place an apple1 which we will call the ,earth1 on the bottom of an inverted glass on a table1 and draw a chalk circle a foot in diameter around it4 ,next1 take a tablespoon to represent the ,moon1 and hold it upright with the point of its bowl on the chalk line and with the bowl turned toward the apple1 as shown in ,fig4 #ajg4 ,now1 draw the spoon round the circle1 turning it in your fingers so that the bowl is always toward the apple4 ,it is easy to see that in order for the bowl of the spoon to be turned toward the apple during all of its travels round the chalk circle the spoon must also turn once round on its own axis1 and this is the reason we always see the same side of the ,moon4 ,the ,moon's ,phases4--,since one side of the ,moon is always turned toward the ,earth1 it is clear that this is the only side we can ever see1 and1 further1 we are only able to see as much of this side as is made bright by the ,sun's light4 ,illustration3 ,,fig4 #ajh4--;,,apple ,,cut ,,to ,,show ,,crescent4 ,the different aspects we get of the ,moon as it revolves round the ,earth are called the ,moon's phases2 and each phase has a name1 as the new moon2 the first quarter2 the full moon1 and the last quarter4 ,between the new ,moon and the first quarter1 and between the last quarter and the new ,moon only a crescent1 or sickle-like edge of the ,moon1 can be seen2 while between the full ,moon and last quarter the ,moon is gibbous 7pronounced gib-us and meaning swelled1 or shaped like a football74 ,if you will look at the picture1 ,fig4 #ajh1 and the diagrams1 ,figs4 #aji and #aaj1 and do the experiment which follows1 the way the phases of the ,moon are made will be perfectly clear4 ,the picture1 ,fig4 #ajh1 shows an apple from which a thin sector or slice has been cut4 ,the lower picture shows the stem end of the apple and from this point of view the part where the slice was cut out looks wedge-shaped4 ,this is the view of the ,moon shown in ,fig4 #aji1 if we could look down on it4 ,illustration3 ,,fig4 #aji4--;,,diagram ,,showing ,,how ,,the ,,moon',s ,,phases ,,are ,,made4 ,now turn the apple on its side and the place where the slice was cut out can be seen from the stem to the blossom end of the apple when it takes on a crescent form4 ,this is the view of the ,moon we really get between new ,moon and its first quarter1 as shown in ,fig4 #aaj4 ,the diagrams1 ,figs4 #aji and #aaj1 show the ,earth in the center of the ,moon's orbit and the ,moon is pictured in eight positions1 as it moves round the ,earth1 one for each phase1 while the sunlight falling upon the ,earth and the ,moon is shown by streamers of light from the ,sun above4 ,the diagram1 ,fig4 #aaj1 shows how the sunlight falls on the ,moon1 but you must always keep in mind that only that part of the ,moon which is in the sunlight and which is also inside of the line of its orbit can be seen from the ,earth4 ,illustration3 ,,fig4 #aaj4--;,,diagram ,,of ,,the ,,moon',s ,,phases ,,as ,,we ,,see ,,them4 ,starting now with the new ,moon1 ,fig4 #aji1 it will be seen that the ,moon is directly between the ,earth and the ,sun and hence that part of the ,moon toward the ,earth is in the shadow4 ,now1 since the eye can see nothing in the sky which is not shining1 and since the ,moon rises and sets at the same time as the ,sun1 we cannot see it4 ,as the ,moon moves on round the ,earth in the direction of the arrow and while half of it is in the light and half of it is in the shadow as before1 from our position we are now able to see a narrow strip of its bright surface which in ,fig4 #aji is shown as a wedge1 but since we are looking at it from an angle we see it as a crescent1 as shown in ,fig4 #aaj4 ,the ,moon having reached its first quarter sets at midnight and from the ,earth half of its bright surface can be seen1 which of course is only one quarter of the ,moon's whole surface4 ,the next phase of the ,moon is when nearly all of its bright side can be seen4 ,this is the gibbous phase and the ,moon then seems to be about the shape of a football4 ,after the gibbous phase the full moon appears and this takes place in that part of the sky opposite the setting ,sun4 ,when the ,moon is full it shines all night and does not set until sunrise4 ,from this time on the bright part of the ,moon which we can see grows less and the gibbous phase again takes place4 ,soon the ,moon reaches its last quarter and gradually the straight rough edge is hollowed out and another crescent is formed4 ,the ,moon is now in the east and the horns of the crescent point to the west1 just opposite to the direction the horns of the new ,moon pointed4 ,the horns of the new and old crescents always point away from the ,sun and this also is a good thing to remember4 ,to show how the ,moon changes its phases perform the following simple experiment3 ,peel half an orange and push a knitting needle through its center and let this be the ,moon4 ,your eyes will serve for the ,earth and a lighted lamp will make a very good ,sun1 all of which is shown in ,fig4 #aaa4 ,hold the orange by the knitting needle well out from your body with the peeled side toward you1 and in such a position that the orange will be between your eyes and the lamp4 ,the side of the orange toward you will be in the shadow and this represents the new ,moon4 ,now slowly turn your body round to the left and always hold the orange with the peeled side toward you4 ,you will see that the light from the lamp striking the orange forms a crescent with its horns pointing away from the light4 ,keep on turning1 a little at a time1 and soon a quarter of the orange will reflect the light and this is like the first quarter of the ,moon4 ,when you have turned nearly halfway round nearly half of the orange will shine by the reflected light of the lamp and you will have a fair example of the gibbous ,moon4 ,when you have turned your back to the light hold the orange above your head so that your shadow will not hide it2 now half of the orange--the half that is peeled--reflects the lamp-light and represents the ,moon when it is full4 ,illustration3 ,,fig4 #aaa4--;,,boy1 ,,lamp ,,and ,,orange ,,showing ,,phases ,,of ,,moon4 ,as you keep turning round the amount of light reflected by the orange1 which you can see grows less and less1 the bright part at first being gibbous1 then the last quarter is seen1 after that a thin crescent1 and finally when you have turned completely round the orange is again between your eyes and the light1 hence it can no longer be seen1 and the new ,moon phase is again at hand4 ,the ,harvest and ,hunter's ,moon4--,you will remember that on ,september #ba the days and nights are equal and this is called the ,autumn ,equinox4 ,the full moon that falls nearest to ,september #ba is called the ,harvest ,moon as it rises at nearly the same hour for several nights in succession and this makes several long moonlight evenings in succession4 ,the ,hunter's ,moon follows the ,harvest ,moon4 ,how the ,moon ,makes the ,tides4--,when we are at the seashore we soon see that there is a regular rise and fall of the ocean4 ,this rise and fall of the waters is called the tide1 and if we note the time when the waters have reached the highest point--which is called high tide--we will find that a little over six hours later the waters have reached their lowest point--or low tide4 ,before the tide has reached the high point again another six hours and some minutes have passed so that from one high tide to another high tide #ab hours and #be minutes have elapsed4 ,these tides are chiefly caused by two forces acting on the oceans1 one being the attraction of the ,moon for the ,earth1 and the other being the centrifugal force set up by the ,earth's motion round its axis4 ,the effect of the ,moon's attraction for the ,earth is to pull the water of the ocean on the side of the ,earth nearest it1 and this forms a bulge1 or great wave1 while on the other side of the ,earth the ,moon's attraction is smaller for the water than it is for the solid ,earth1 so the ,earth is pulled away from the water4 ,thus two tidal waves are formed at the same time1 one on each side of the ,earth1 as shown in ,fig4 #aab4 ,illustration3 ,,fig4 #aab4--;,,attraction ,,of ,,the ,,moon ,,causes ,,the ,,tides4 ,since the ,earth revolves round its axis once in #bd hours these tidal waves go round the ,earth and as there are two tidal waves each day there are two high tides and two low tides at every place on the ocean1 but these are chiefly noticeable on the coasts4 ,fig4 #aab shows the position of the ,moon and the ,earth1 while the wavy lines around the ,earth represent the oceans4 ,spring ,tides and ,neap ,tides4--,not only does the ,moon's attraction cause the tides1 but the ,sun's pull on the ,earth also produces tides4 ,when the ,sun and ,moon are in a line with the ,earth they pull together and the tides are raised very high and they fall very low1 and these high and low tides are called spring tides4 ,since we have either new ,moon or full ,moon1 when the ,sun1 ,earth and ,moon are in a line1 the spring tides occur at these times1 or twice every month4 ,figs4 #aac and #aad show how the spring tides are formed4 ,illustration3 ,,fig4 #aac4--;,,how ,,spring ,,tides ,,are ,,formed4 ,illustration3 ,,fig4 #aad4--;,,how ,,spring ,,tides ,,are ,,formed4 ,when the ,moon is at its first quarter1 as in ,fig4 #aae1 or in its last quarter1 as in ,fig4 #aaf1 the ,sun's pull and the ,moon's pull oppose each other and the high tides are lowest4 ,these low high tides1 which take place twice a month1 are called ,neap tides4 ,a ,trip to the ,moon4--,many stories have been told about imaginary trips to the ,moon and what the adventurers saw after reaching their destination4 ,our story is made up of facts and the only thing we shall imagine is that we have made the trip and set foot somewhere on the ,moon4 ,having performed this mental somersault we shall carefully leave out all the hard questions about living there without air and water1 for this is a pleasure trip and we don't want to spoil the fun with details4 ,on landing after our #bdj1jjj-mile trip we find that there is not only neither air nor water1 but that the ,moon is stone cold2 even when the ,sun shines on it1 it is freezing cold1 while the temperature drops to perhaps #cjj degrees below zero when the ,moon's night comes on4 ,our next observation will probably be that we feel much lighter than we did on ,earth and we are lighter in the very nature of things1 for the weight of bodies on the ,moon is only one-sixth as much as they are on the ,earth4 ,this is due to the ,moon being so small and light that gravity has only one-sixth as great an attractive force there as it has on the ,earth4 ,supposing we still retained on the ,moon as much strength as we had on the ,earth2 then every time we took a step we would cover a distance of #ae or #bj feet2 if we jumped we would sail through space with the agility of a ,harlem goat1 and if we played ball and batted the sphere fairly it would shoot off a quarter of a mile and go twice as far from the home plate4 ,illustration3 ,,fig4 #aae4--;,,how ,,neap ,,tides ,,are ,,formed4 ,illustration3 ,,fig4 #aaf4--;,,how ,,neap ,,tides ,,are ,,formed4 ,since there is no air on the ,moon1 in order to see one another the ,sun would have to shine directly on us1 and if by any chance we should get into a shadow we would be as completely lost to view as if we had fallen into one of the craters1 for a shadow on the ,moon is as deep and black as the darkest night you ever saw on ,earth4 ,shadows as we know them on the ,earth are always softened1 for the air scatters the light4 ,nor would it do us any good to cry out or whistle1 for1 since sound waves are carried by the air1 and since there is no air on the ,moon1 all our efforts to make ourselves heard would be useless1 even if we were only a few feet from each other4 ,the ,moon is just as silent and cold and still as it looks1 for1 though it serves the ,earth well as a mirror to reflect the ,sun's light1 it is1 after all1 only a great1 burned-out cinder4 ,looking at the sky at night from the ,moon1 we are surprised to find how much bigger and brighter the stars seem1 and how many more of them can be seen1 than from the ,earth4 ,here we see as many with the naked eye as we could see from the ,earth with a three-inch telescope4 ,the ,earth itself is seen like a mighty ,moon--a ,moon as bright as #dj of the ,moons we are calling on1 and so large is it that we can see1 not only the continents and oceans1 but the polar ice caps and the plains and the mountains as well1 as we see objects of same size on ,moon1 as shown in ,fig4 #aag4 ,illustration3 ,,fig4 #aag4--,,view ,,of ,,the ,,earth ,,from ,,the ,,moon4 ,watching the ,earth from this new viewpoint1 we see it turn on its axis every #bd hours and going through all the phases--crescent1 quarter1 gibbous and full1 and back to crescent again1 just as the ,moon does when we see it from the ,earth4 ,more curious than the ,earth is the view we get of the ,sun from the ,moon1 the lack of air making the seeing so good that the spots on the ,sun1 the fiery prominences and the thin corona can all be easily seen with the naked eye4 ,when the ,moon is new the whole half of the ,earth that is turned toward the ,moon is sunlit and by its reflected light we can easily read our time-card--for we must get back to ,earth again and either write a book or lecture about the wonders we have seen4 ,the ,moon and the ,weather4--,we have seen in ,chapter ,,iii that our weather is entirely dependent on the ,sun4 ,still it is believed by many persons today that the ,moon has also something to do with the changes in the weather1 just as it is the cause of the tides4 ,illustration3 ,,fig4 #aah4--,,telling ,,time ,,by ,,the ,,moon4 ,hence there have been handed down to us a large number of old sayings to show what the weather will be during certain phases of the ,moon4 ,but it has been proved by records kept of the weather that the ,moon has nothing whatever to do with it4 ,for this reason no reliance is to be placed in any forecast of the weather which is founded on changes of the ,moon4 ,how to ,tell ,time by the ,moon4--,after having learned how to tell the hour of the day by the ,sun you should learn to tell the hour of the night by the ,moon4 ,on some nights this is a very simple thing to do1 for when the ,moon is full it is due south at exactly #ab o'clock midnight1 as shown in ,fig4 #aah4 ,every night before the ,moon is full you will find it due south #ee minutes earlier1 so that you must subtract #ee minutes from #ab o'clock for each day2 that is1 one day before full ,moon it is due south at #aa3je ,p4 ,m42 two days before full ,moon it is due south at #aj3aj ,p4 ,m42 three days before full ,moon it is due south at #i3ae ,p4 ,m41 and so on4 ,after the ,moon is full it will be due south #ee minutes later every night and then you must add #ee minutes to #ab o'clock2 that is1 one day after full ,moon it is due south at #ab3ee ,a4 ,m42 two days after full ,moon it is due south at #a3ej ,a4 ,m42 three days after full ,moon it is due south at #b3de ,a4 ,m41 and so on4 ,the ,moon's day is #bg of our days long4 ,the ,moon's year is #bg of our days long4 ,the ,moon's diameter is #b1afj miles4 ,the distance from the ,moon to the ,earth is #bdj1jjj miles4 ,,chapter ,,vii ,,other ,,things ,,in ,,the ,,sky ,seeing an ,eclipse4--,the word eclipse is taken from the ,greek and means to fail to appear4 ,in starcraft1 when the ,earth passes across the ,sun1 and the ,moon is hidden in its shadow1 we say that it is an eclipse of the ,moon2 or when the ,moon passes across the ,sun and covers it we say that there has been an eclipse of the ,sun4 ,how eclipses of the ,sun and of the ,moon are caused can be shown by a very simple experiment and you ought to make it4 ,an ,eclipse of the ,moon4--,first let us suppose it is the ,moon which is eclipsed by the ,earth4 ,all that is needed to show how this is done is a lighted lamp on a table and an apple with a knitting needle through its center4 ,let the flame of the lamp represent the ,sun1 your head the ,earth and the apple the ,moon4 ,illustration3 ,,fig4 #aai4--;,,eclipse ,,of ,,the ,,moon ,,by ,,the ,,earth 7,,experiment74 ,hold the apple by the knitting needle in a line between your eyes and the flame and turn round just as you did in the experiment showing the phases of the ,moon4 ,when you have turned halfway round the apple will be in the shadow of your head1 when the apple is eclipsed1 as shown in ,fig4 #aai4 ,this is just what happens when the ,earth gets between the ,sun and the ,moon and all these bodies are in a straight line1 as shown in ,fig4 #abj2 the ,moon will then be in the shadow of the ,earth1 and thus it is that the ,moon is eclipsed4 ,illustration3 ,,fig4 #abj4--,,moon ,,eclipsed ,,by ,,the ,,earth 7,,diagram74 ,if the ,sun1 ,earth and ,moon were always in the same plane with each other1 every time the ,earth passed between the ,sun and the ,moon the latter would be plunged into the ,earth's shadow and the ,moon would be eclipsed4 ,but the ,moon does not revolve round the ,earth so that it and the ,earth make a straight line with the ,sun every revolution for the reason that the ,moon's orbit is tilted a little and hence it is only once in a while that all of these bodies get in a straight line with each other1 and when these times do happen then eclipses are produced4 ,illustration3 ,,fig4 #aba4--,,the ,,moon ,,as ,,seen ,,when ,,in ,,eclipse4 ,again when the ,moon is eclipsed it is not always entirely hidden from view by the great shadow of the ,earth1 for the air on the ,earth sends the sunbeams round it so that the shadow is never very deep1 and for this reason the ,moon can still be seen1 as shown in ,fig4 #aba4 ,so1 then1 some of these bent sunbeams fall on the ,moon and are reflected from its surface back to us and it is then that we see the ,moon in an entirely new light4 ,sometimes during an eclipse of the ,moon the man can still be seen1 but instead of having a bright silvery face he will have changed it to the copper color of a red ,indian4 ,the whole eclipse of the ,moon often lasts longer than six hours and sometimes the moon is in the deep shadow of the ,earth as long as two hours4 ,illustration3 ,,fig4 #abb4--;,,eclipse ,,of ,,the ,,sun ,,by ,,the ,,moon 7,,experiment74 ,illustration3 ,,fig4 #abc4--,,the ,,sun ,,eclipsed ,,by ,,the ,,moon 7,,diagram74 ,a total eclipse is one in which the ,moon passes completely into the shadow of the ,earth1 while a partial eclipse is one where only part of the ,moon is in the shadow of the ,earth and part of it is in the sunlight4 ,eclipses of the ,moon occur quite often and you can look up the time of the next one in your almanac4 ,eclipse of the ,sun4--,when the ,sun is eclipsed it is caused by the ,moon passing between the ,earth and the ,sun and so the light is cut off from the former4 ,to show how this is done all that is needed is to continue the experiment with the lighted lamp and the apple which you used for the eclipse of the ,moon4 ,you will remember in that experiment you were turned with your back to the lamp and with the apple held in front of you4 ,now to show how the ,sun is eclipsed by the ,moon keep on turning round until you face the lighted lamp with the apple in between and in a straight line with your eyes and the flame1 as shown in ,fig4 #abb4 ,again you will find that the side of the apple nearest you will be in a deep shadow1 though usually it can still be seen1 and though you can see the light all round the apple yet you cannot see the flame4 ,this is exactly what takes place when the ,moon gets between the ,earth and the ,sun and all of these bodies are in a straight line1 as shown in ,fig4 #abc2 the ,moon will then cover up the ,sun and the shadow of the ,moon will fall upon the ,earth in a circle about #ajj miles in diameter1 as shown in ,fig4 #abd4 ,it is thus that the ,sun is eclipsed4 ,illustration3 ,,fig4 #abd4--,,total ,,eclipse ,,of ,,the ,,sun1 ,,showing ,,path ,,of ,,the ,,sun4 ,illustration3 ,,fig4 #abe4--,,total ,,eclipse ,,of ,,the ,,sun1 ,,from ,,photo4 ,illustration3 ,,fig4 #abf4--;,,annular ,,eclipse ,,of ,,the ,,sun4 ,illustration3 ,,fig4 #abg4--,,partial ,,eclipse ,,of ,,the ,,sun4 ,as the ,moon is traveling round the ,earth and the ,earth is turning round on its own axis1 the ,moon's shadow moves across a path or trail that is only about #ajj miles wide1 and it moves very fast1 too1 for it usually takes less than five minutes for the ,moon to sweep over the face of the ,sun4 ,there are three kinds of eclipses of the ,sun4 ,the first is called a total eclipse1 and this takes place when the ,moon covers the entire face of the ,sun1 as in ,fig4 #abe4 ,the second is called an annular eclipse and this takes place when the ,moon does not completely cover the ,sun but leaves a bright ring exposed1 as shown in ,fig4 #abf4 ,the reason the ,moon covers the ,sun completely during a total eclipse and does not cover all of it during an annular eclipse is because the orbit of the ,moon around the ,earth is not a perfect circle1 and so sometimes the ,moon is nearer the ,earth than at other times and this makes the ,moon seem larger or smaller1 as the case may be4 ,the third kind is called a partial eclipse4 ,if we are not in the direct path of the shadow of the ,moon we may see the ,moon pass over only a part of the ,sun1 as shown in ,fig4 #abg4 ,the only total eclipses of the ,sun which can be seen in the ,united ,states in the next #cj years are the following3 ---------------------------------------- ------------------------- ,date of ,time of ,eclipse ,total ,phase ,course of ,moon's ,shadow ---------------------------------------- ------------------------- #aiah1 ,june #ah1 #b minutes ,oregon to ,florida #aibb1 ,sept4 #b1 #f minutes ,pacific ,ocean1 ,u4 ,s4 ,west ,indies #aibc1 ,sept4 #aj1 #c minutes ,u4 ,s4 ,atlantic ,ocean #aicj1 ,april #bh1 #b seconds ,u4 ,s4 ,canada #aide1 ,july #i1 #a minute ,u4 ,s41 ,canada1 ,scandinavia and ,russia ---------------------------------------- -------------------- ,note3 ,the eclipse of #aicj will be an annular eclipse4 ,finding a ,comet4--,to the naked eye a great comet looks like a bright star with a long1 glowing tail4 ,in the long ago a comet was called a hairy star1 for the early ,greeks pictured the tail of a comet as being made of long hair and so from their language we get the word comet1 which means hair4 ,illustration3 ,,fig4 #abh4--;,,comet ,,showing ,,nucleus1 ,,coma ,,and ,,tail4 ,a comet is really made up of three parts1 which are1 7#a7 a bright head or core1 called a nucleus1 and this is covered with 7#b7 a layer of hazy light1 called a coma1 to which there is attached 7#c7 a luminous tail1 all of which is shown in ,fig4 #abh4 ,the nucleus of a comet is formed of a bunch of stones and pieces of iron1 all widely separated and which are held together by attraction as they speed through space4 ,as a comet nears the ,sun it begins to get hot and to throw off burning gases1 which make up its coma1 and these bright gases streaming along form its tail4 ,there are several ways in which a comet can be told from the planets4 ,in the first place1 new comets1 that is1 comets which have never been discovered before1 appear suddenly and in any part of the sky1 though they may be very dim at first1 and after a while they fade away1 sometimes never to return again4 ,illustration3 ,,fig4 #abi4--;,,an ,,ellipse1 ,,parabola ,,and ,,hyperbola4 ,second1 they shine chiefly with their own light like the stars2 third1 they do not travel in small circles around the ,sun like the planets2 but the paths they take are either long ovals1 called ellipses1 or great curves whose ends never meet1 called parabolas and hyperbolas1 as shown in ,fig4 #abi2 fourth1 they do not travel through space in a line with the planets and ,sun1 but shoot in and out of our solar system from and to every direction2 and fifth and last1 they travel at enormously high speeds4 ,now1 a comet1 however great it may grow to be1 never bursts into view1 big1 bright and beautiful1 but when one is found it is usually seen as a little1 dim patch of light1 and it would quite likely be mistaken for a nebula1 if it did not move along so swiftly4 ,illustration3 ,,fig4 #acj4--;,,head ,,and ,,tail ,,of ,,comet ,,do ,,not ,,obey ,,the ,,same ,,laws4 ,a comet can be told by its movement and its movement can be plotted in the same way ,i have described for plotting the position of a planet in ,chapter ,,iv2 and so1 if you see a dim1 little ball of light in the sky and find that it changes its position when compared with the fixed stars near it you may guess that you have discovered a comet4 ,the next thing you should make sure of is1 that you have not found one of our old familiar friends1 the planets4 ,if it is really a great comet coming toward the ,sun1 it will grow larger and brighter every night1 and you will soon be able to see its tail1 which is the real earmark of a really truly comet4 ,when a comet is nearest us its head may shine far brighter than any of the planets1 and its great tail may be millions of miles in length1 and spread out in a glowing arc and light up the whole sky4 ,when this time comes a comet is by far a greater sight to the naked eye than it is when seen through the largest telescope4 ,you should observe the comet often and carefully1 for another one may not appear for a long time4 ,illustration3 ,,fig4 #aca4--;,,halley',s ,,comet1 ,,from ,,photo4 ,the nearer a comet gets to the ,sun the faster it travels2 some comets have been known to move a thousand times as fast as a rifle-ball1 and this is the more surprising when we consider that the great1 flaming tail goes along with it at the same terrific rate of speed4 ,the tails of comets do some very strange things2 for example we should rather expect the tail of a comet to always follow its head like a skyrocket1 but while it does so when the comet is headed toward the ,sun1 when the comet is passing round and shooting into space the tail turns away from the ,sun1 and this causes it to move ahead of the comet1 as shown in ,fig4 #acj4 ,this shows that while the head of a comet obeys the laws of gravitation1 the tail does not do so1 but acts as if it was electrified like the ,sun1 when of course it would be repelled by it4 ,fig4 #aca is a picture of ,halley's comet of #aiaj4 ,although a great astronomer once said that there are more comets in the sky than fishes in the sea1 there have only been #a1jjj comets recorded since the beginning of written history4 ,illustration3 ,,fig4 #acb4--,,meteorite ,,of ,,iron ,,etched ,,with ,,acid4 ,meteors and ,meteorites4--,if you will look at almost any part of the sky on a clear night when there is no ,moon you will no doubt see a bright flash like a rocket4 ,but if you will scan the sky during the dark nights of ,august and ,november you will be very apt to see dozens of these shooting stars or meteors4 ,now1 meteors1 fireballs1 shooting stars and meteorites are all one and the same thing to start with and they have their beginnings when some comet goes to pieces4 ,after a comet breaks up1 the pieces of stone and iron which form it still travel round in the same orbit4 ,some of these pieces may get within range of the ,earth's force of gravitation when they are drawn to it1 and on striking the air they are intensely heated by the friction1 and if they are small they burn up before reaching the ground4 ,the smaller meteors burn up almost instantly and the shining tails they leave last only a few seconds4 ,fireballs1 which are simply large meteors1 leave burning trails which can sometimes be seen for several minutes4 ,shooting stars are merely meteors which are not very bright1 while meteorites are meteors which have fallen to the ,earth before they have had time to burn up4 ,many meteorites have been found1 but ninety-five out of every hundred are of the stony kind1 the others being of the iron kind4 ,the way to tell a meteorite from a common stone is by examining its surface4 ,a true meteorite is covered with a black1 shiny1 burnt crust1 caused by the intense heat to which it was subjected as it fell through the air4 ,the test for an iron meteorite is to grind and polish a part of its surface and then cover it with a dilute solution of nitric acid1 when markings like those shown in ,fig4 #acb will be etched upon it4 ,illustration3 ,,fig4 #acc4--,,the ,,milky ,,way4 ,the ,milky ,way4--,you have1 no doubt1 often seen on a clear1 dark night1 a wide1 ragged band of light stretching from the northern sky across the celestial equator and beyond4 ,this band of light is the famous ,milky ,way4 ,if1 as you were looking at the ,milky ,way1 the ,earth could be moved from under you and you were left standing in space alone so that you could see in every direction1 you would find that the band formed a complete ring round the sky4 ,to the naked eye the ,milky ,way seems to be made up of mists of matter as thin as the stuff of which comets' tails are made4 ,there are some patches1 though1 that are very bright1 but look at them as long as you will with the naked eye nothing more can be seen than just a milky patch of hazy white1 as shown in ,fig4 #acc4 ,with a very small telescope1 however1 this band of luminous matter will be instantly changed into thousands of stars1 all separate and distinct1 and some of these stars will look about as large as the stars of the ,pleiades when these are seen with the naked eye1 while others will shine as brightly as ,venus or ,jupiter when they are nearest to the ,earth4 ,these bright patches1 then1 which form the ,milky ,way1 are really groups of stars or star-clusters1 and when some of these clusters are photographed through a telescope as many as #ae or #bj thousand stars can be counted1 while the real number of stars that lie beyond and which cannot be seen is past all calculation1 and1 just think of it1 every one of these stars is a ,sun as large or larger than our ,sun6 ,those who have made a deep study of starcraft tell us that our ,sun is one of the stars of the ,milky ,way1 and since the other fixed star that is nearest to us1 which is ,alpha ,centauri1 is #be trillion miles away1 and ,sirius1 the ,dog ,star1 which is the brightest star in the whole sky1 is three times as far away as ,alpha ,centauri1 we may gain some slight idea of the enormous distances of the fainter stars that make up the ,milky ,way4 ,the ,nebul4--,unlike the bright1 cloud-like patches in the ,milky ,way1 and which the telescope shows to be formed of separate and distinct stars1 are the faint misty spots in the sky called nebul 7or nebule74 ,now the nebul give us a clew as to how the stars were made1 and how other stars are now being made1 for it is believed that the nebul are the raw material which1 when set in motion1 produced heat and took on form and became ,suns and planets like our own solar system4 ,the nebul are formed of luminous gas4 ,some of them are great irregular clouds of gas1 many are more or less spiral in form1 others are condensed so they look like fuzzy stars4 ,there are a few of these nebul which can be seen with the naked eye2 one of these is the ,great ,nebula of ,orion1 and if you will look at ,orion some night and draw an imaginary line a little below his belt and toward the east you will be able to find it4 ,another nebula that is bright enough to be seen with the naked eye is the ,great ,nebula in ,andromeda4 ,both of these nebul are good tests for eyesight4 ,fig4 #acd shows some of the different forms of nebul4 ,illustration3 ,,fig4 #acd4--;,,different ,,forms ,,of ,,nebul4 ,the ,making of the ,stars4--,to explain how our ,sun and the planets were made1 as well as all the other stars in the universe1 two ideas have been worked out1 and although these are quite unlike in many ways1 yet both start out with the nebul4 ,the first of these is called the nebular hypothesis and the other and later one is called the planetesimal hypothesis4 ,the ,nebular ,hypothesis4--,we have found out what nebula is believed to be and we should next understand exactly what the word hypothesis means4 ,an hypothesis is an idea worked out so that there is a fairly good chance of its being true4 ,the nebular hypothesis1 then1 is an idea that has been worked out from what nebul are believed to be and what is known of the mighty forces of nature1 and these when taken together seem to show that all the things in the sky--stars1 planets1 moons1 comets and meteors--are made of nebular stuff4 ,the nebular hypothesis says that when the nebular matter1 or star stuff of which the planets were made1 was separated from the parent nebula by centrifugal force1 they were all whirled away in the same plane1 turning on their own axes and traveling round the ,sun in the same direction4 ,the ,planetesimal ,hypothesis4--,a later idea1 is called the planetesimal hypothesis4 ,planetesimal means little planet1 and as we know already what hypothesis means1 by coupling the two words together we may easily guess that it is an idea worked out which accounts for the making of solar systems out of little planets4 ,the planetesimal hypothesis assumes that the sun1 planets1 and moons comprising the ,solar ,system were formed from a star which was torn to pieces by another star which passed close by4 ,the star was left in the form of a spiral nebula rather lumpy and with little particles of matter scattered all around4 ,the meteors1 or little planets1 making up the nebula1 attract each other1 like all other bodies1 and when they get close enough they are drawn together and dense masses of matter1 or cores1 are built up4 ,the largest core is seen in the center of a spiral nebula1 and as it becomes more compact it grows hotter and a ,sun is made1 while the other and smaller cores turn round it and attract little planets to them4 ,and so the cores grow in size1 and with more and more weight bearing toward their centers the gases are forced out and these make the air and water4 ,it is in this manner that the planetesimal hypothesis explains how the ,sun1 planets and ,moons of the solar system are made4 ,,chapter ,,viii ,,seeing ,,the ,,stars ,how the ,stars ,shine4--,a burning match1 a candle1 an oil or gas flame1 the ,sun1 comets and meteors all give out light and heat in exactly the same way1 but the heat and light are made differently4 ,when you strike a match the friction makes enough heat to light the chemicals of which the head is formed and the burning gases light the splint which in turn generates more gases from the wood and these give out more light and heat4 ,when you light a candle the heat melts the wax which is then drawn up the wick1 the burning gas around the wick produces more gas and the gas keeps the flame going4 ,in the case of an oil lamp the oil1 which is already a fluid1 is drawn up by the wick1 where it is changed into gases1 and light and heat result as in the candle4 ,the oil lamp is1 then1 a step ahead of the candle1 for the solid wax is replaced by the fluid oil4 ,in the gas light the gas1 which is made of coal or other matter1 is forced out of the jet under pressure and this gives a bigger and better flame than the oil lamp2 and1 as the oil lamp is better than the candle1 so the gas jet is an improvement over the oil lamp4 ,now the ,sun1 and this is also true of most of the stars1 is so large and hot that if any solid matter1 such as iron and other metals could be thrown into the ,sun they would not only be melted but instantly changed into gases4 ,further1 the ,sun is so hot that the materials cannot combine with ,oxygen--in other words they cannot burn4 ,the intensely hot gases of the ,sun radiate the light and heat and we suppose that they keep themselves hot largely by contraction4 ,when a comet comes close enough to the ,earth to be seen it is then close enough to the ,sun so that the light and heat of the ,sun cause some of the gases of which the nucleus of the comet is formed1 to become white hot2 as a comet gets closer to the ,sun the solid matter of the nucleus1 such as sodium--which is a kind of salt--iron and other things are changed into gases and these burn fiercely4 ,while we can see the light of a comet we cannot feel its heat1 for a comet is too small to send its heat waves through such a great distance4 ,just as a match is lit by striking it1 so meteors are set on fire by striking the air4 ,meteors are made up of the same kind of matter as comets and when these shooting stars come within the attraction of the ,earth the friction caused by the meteor rubbing against the air is so great that an intense heat is produced and the gases burst into flame4 ,if a meteor is small it is entirely burned up before it reaches the ,earth and all we see of it is a bright streak of light4 ,if a meteor is large enough only the outside of it is burned and it will1 in consequence1 reach the ,earth1 when it becomes1 as explained in the last chapter1 a meteorite4 ,meteors and meteorites produce a very bright light1 burning as they do in the oxygen of our air1 and though they are very close to us they are so small we cannot feel any heat sent out by them4 ,we have said that when a match is struck the friction produces heat and that when the wax of a candle1 the oil of a lamp or the gas of a jet is burned they produce light and heat1 and this is also true of the blazing ,sun1 the fiery comets and the burning meteors4 ,where there is light there is usually heat and turn about where there is heat there is light if the temperature is high enough4 ,heat is produced before light1 but the two are nearly always found together and they are so much alike they might be called the ,siamese twins4 ,what ,heat and ,light ,are4--,we know that both heat and light are caused by burning gases1 but let's get a little closer and find out just how and why gases which are burning send out heat and light4 ,now gases are formed of particles of matter called atoms and these atoms are very small but they have a certain size and weight according to the substance they form4 ,when these gases are cold the atoms are comparatively quiet1 but when they are heated to a high temperature they are thrown into a violent state of motion and vibrate to and fro a given number of times per second1 or frequency1 as it is called1 according to the substances they are made of4 ,the next question in order is what makes the particles1 or atoms move1 or vibrate and the answer is heat1 which sometimes produces burning4 ,combustion1 or burning is a chemical action and can be explained by saying that it is the combining of a substance with oxygen1 or other substance with the production of heat and light4 ,the only difference between heat and light is that of wave length as we shall see presently1 and the length of heat waves and of light waves depends entirely on the rapidity with which the atoms vibrate1 or the frequency of vibration1 as it is called4 ,if the atoms of gas move slowly heat is sent out and if the atoms move rapidly the heat grows more intense and light is radiated4 ,when the atoms of a burning gas vibrate just fast enough to produce light the color of the light is red2 when the atoms vibrate still faster the color of the light is green and when the atoms vibrate very fast the light sent out is violet1 so we see that not only do the vibrating atoms send out light but that the rapidity1 or frequency with which they vibrate makes1 or determines1 the color as well of the light which is sent out4 ,one thing more3 the rapidity of the motion1 or vibration1 of the atoms of a gas depends entirely on the substance which is being burned1 so that certain substances when burning always produce certain colors4 7,see ,chapter ,,xii1 ,what the ,stars ,are ,made ,of47 ,how ,heat and ,light ,travel4--,while the little motions or vibrations1 of the particles1 or atoms1 of gas forming the flame of a candle1 the ,sun1 and other heat and light givers could go on just the same we could not feel their heat or see their light without something or some kind of a substance which would connect them with our bodies and our eyes1 like a wire connecting a push button with an electric bell4 ,and there is something which connects us with the most distant stars and that something is called the ether4 ,illustration3 ,,fig4 #ace4--,,ripples ,,or ,,waves ,,on ,,water4 ,to show how these little movements1 or vibrations set up by the atoms of a flame impress us as heat or light do at a distance we will begin with a simple experiment to show what the ether is and how it acts4 ,if you will stand on the edge of a pool of water and throw a stone into the middle of it you will see a little ring-like ripple1 or wave start out from the point where the stone struck the water2 this ripple1 or water wave will continue to grow larger and larger in diameter and weaker and weaker until it reaches the edge of the pond1 as shown in ,fig4 #ace1 or if the pond is very large the waves will die out before they reach the edge4 ,again1 if you toss a number of stones into the middle of the pond one after another a series of ring-like waves will follow from the center of the pond where the stones strike the water to the edge of the pond1 or until they die out4 ,in the same manner if a bell is struck by a blow of its tongue1 ripples1 or waves in the air will be sent out all around the bell4 ,these waves in the air are called sound waves1 but they are1 after all1 only air waves4 ,when a bell is struck the rim of the bell moves forth and back1 first in one direction and then in the other1 as shown in the diagram1 ,fig4 #acf1 and we call these little movements of the bell vibrations4 ,the movements are so small that you cannot see them1 but if you put your finger on the bell you can feel them4 ,although the vibrations of a bell are very small they are powerful enough to set up ripples1 or waves in the air as shown in ,fig4 #acg1 and when these air waves or sound waves strike the drum of the ear it vibrates just like the bell and the auditory nerve of the ear carries the waves on to the brain and we hear the bell ring4 ,illustration3 ,,fig4 #acf4--,,vibration ,,of ,a ,,bell4 ,it must be plain now that if there was no air connecting the bell with our ears the bell might keep on ringing and yet we could not hear it4 ,when the air is set in motion by the vibrations of a bell1 or any other device for producing from #cb to #dj1jjj vibrations per second1 we can hear it1 and when the air moves as a mass1 as when the wind blows1 we can feel it4 ,air forms a layer around the ,earth that is between #bjj and #cjj miles thick1 but out in the great space beyond there is no air4 ,yet the space is not empty1 but it is filled instead with a substance called the ether4 ,just as the air is finer than water so the ether is a million times finer than the air4 ,it is so fine that it fills up all the little spaces between the particles or atoms of water and of the air1 and it penetrates in between the atoms of the densest metals and the hardest glass1 and further1 and still more wonderful1 it fills all of the great space in which the planets and the stars are placed4 ,now when the particles1 or atoms of gas are set in motion1 or vibration by a flame of any kind1 be it a candle or the ,sun1 little ripples or waves are started in the ether and if these waves are very short they affect the eye and cause the optic nerve to vibrate exactly like the vibrations which are sending out the ether waves and these waves are carried to our brains and we see the light4 ,the way in which a flame sends out waves in the ether and is received by the eye1 is shown in ,fig4 #ach4 ,illustration3 ,,fig4 #acg4--,,sound ,,waves ,,in ,,the ,,air ,,set ,,up ,,by ,,bell4 ,it takes a ripple1 or wave on the water started by the impact of a stone about one-half second to travel one foot4 ,a sound wave1 set up by the vibrations of a bell1 or other sound producing device1 travels through the air at the rate of #a1jij feet per second1 while light and heat waves set up by the vibrations of a flame1 the ,sun or other hot body1 travel through the ether at the rate of #ahf1ejj miles per second4 ,it must be plain now that if there was no ether connecting the flame1 or the ,sun with our eyes the flame1 or ,sun might continue to send out light and yet we could not see it4 ,how the ,eye ,sees4--,if it was not for our ears we could not hear a bell ring nor any sound1 for though the waves in the air might still be sent out we would have no means of receiving them2 again if it was not for our eyes we could not see a flame1 the ,sun or any other source of light and1 what would be worse1 we could not see an object by its reflected light1 for though the waves in the ether would still be sent out we would have no means of receiving them4 ,illustration3 ,,fig4 #ach4--,,waves ,,in ,,the ,,ether4 ,the eye is simply a camera on a very small scale1 but what it lacks in size it makes up by the excellence of its operation4 ,if you will set up a sheet of white cardboard on one end of your starboard1 place a lighted candle at the other end and then hold your burning glass between the flame of the candle and the cardboard1 as shown in ,fig4 #aci1 and do all this in an otherwise dark room1 you will see a picture turned upside down1 called an inverted image1 of the candle flame on the cardboard4 ,to get a sharp picture1 or image of the flame on the cardboard screen you will have to move the lens toward and away from the cardboard1 and this process is called focusing4 ,if you will fix the lens in the front of a light-tight box and place a sheet of ground glass in the back of the box you will have a simple1 though crude1 camera4 ,the eye has all of the things which the highest priced camera has and a good deal more1 for all of its adjustments are automatically made1 and you don't even have to think about them4 ,illustration3 ,,fig4 #aci4--;,,forming ,,an ,,image ,,with ,a ,,lens4 ,the eye is almost as round as a ball and it can be turned a little in its bony socket in any direction4 ,the outer part of an eye which takes the place of the box of a camera1 is stretched round the whole eye like the cover of a baseball1 as shown in ,fig4 #adj4 ,the front part of this cover forms the white of the eye1 and fitting into the cover and over the lens1 like a watch crystal in its rim1 is the cornea1 which is a tough1 but transparent film and protects the iris and the lens4 ,illustration3 ,,fig4 #adj4--,,the ,,human ,,eye4 ,between the lens and the cornea is a thin disk1 or diaphragm with a hole in its center and this is the iris2 the purpose of the iris is to let in only a certain amount of light1 just like the shutter of a good camera4 ,the hole in the iris forms the pupil of the eye1 and you can see the hole1 or pupil1 grow larger or smaller1 just as the eye needs more or less light4 ,the lining of the eye is called the retina and this forms a screen at the back of the eye on which the light waves in the ether project the image of the object at which the eye is looking4 ,instead of being white like our cardboard screen the retina is very black4 ,the retina upon which the image is formed is connected with the optic nerve2 in fact1 the retina is a part of the optic nerve and is covered with a lot of little nerve ends or filaments called rods and cones4 ,now when the waves in the ether sent out by the flame of a candle1 or by the ,sun1 reach the eye1 they pass through the cornea1 then through the pupil1 or hole in the iris1 and finally through the lens which focuses the waves on the retina and forms the image there4 ,the different colors of light are caused by waves in the ether of different lengths2 when very short waves strike the retina we say the color is violet2 waves a little longer we call green and the longest waves which the eye can see form in our brains the sensation of red4 ,waves in the ether which are longer than the wave-lengths the eye can see produce heat and when these waves fall on any part of the body the nerves detect them and we call the sensation heat4 ,on the other hand waves in the ether which are too short to affect the nerves of the eye will impress a photographic plate4 ,the iris of the eye acts as a self-regulating shutter1 which makes the hole1 or pupil in front of the lens larger or smaller according to the amount of light which is needed to see an object well4 ,if the light is strong the iris contracts1 which means that the hole gets smaller and so cuts off some of the light4 ,if the light is weak the hole gets larger and we say the pupil expands and this lets more light through the lens4 ,there must also be some means of adjustment to make a sharp image1 or picture1 on the retina1 however near or far away the object may be from the eye4 ,in a camera this is done by moving the lens and the screen closer together or farther apart and this is the purpose of the bellows of a camera4 ,but the eye has a much finer and quicker adjustment than this for distance4 ,the lens is so made that the front part of it can bend just as the distance changes4 ,you have only to look at an object and the lens is adjusted without the slightest effort or knowledge on your part4 ,you may wonder how light waves can pass through a substance as solid and as hard as glass or through the eye4 ,you will remember ,i told you in the beginning of this chapter how ether got into every little space1 even in metals and glass1 as well as that it filled all the great space between the stars4 ,we think of glass as being very solid1 and it is solid enough to keep water or air in a bottle from getting out through its pores4 ,but glass and the substance of which the eye is made are just about as full of holes as a sieve1 but the holes are so very1 very small you couldn't begin to see them even with the aid of a high-power microscope1 yet they are large enough for the ether to run through just as water runs through a sieve4 ,when ,i tell you that waves in the ether which are sent out by the light of a candle or the ,sun are only about #ae ten-millionths to #cj ten-millionths of an inch in length1 and that the holes1 or pores1 in the glass and the cornea and lens of the eye1 and which are full of ether1 are much larger1 you can readily understand that the ether waves which we call light can merrily pass through either glass or the eye and that there is nothing in the way to stop them4 ,to sum up briefly how the stars shine1 how light travels and how the eye sees we will start with the light of the ,sun and say 7#a7 ,that the ,sun is made up largely of gases1 and that 7#b7 ,these gases are formed of various substances1 and that 7#c7 ,the gases produce terrific heat1 which means that 7#d7 ,the atoms or particles which form the gases are in violent motion or vibration4 7#e7 ,these vibrations start out waves in the ether which travel out into space at a speed of about #ahf1ejj miles per second4 7#f7 ,on reaching the eye the waves pass through the lens and form a picture or image 7#g7 ,on the retina1 or screen of the eye1 which is made up of the ends of nerves1 and these vibrate just as the atoms of the gases in the ,sun which sent out the waves vibrated1 and finally 7#h7 ,these nerve vibrations are sent over the optic nerve to the brain1 where they take on the shape1 size and colors of the ,sun4 ,reflection of ,light4--,the flame of a match1 or a candle1 an oil or a gas lamp1 or ,sun1 comet or meteor1 produces its own light1 and for this reason these bodies are called self-luminous--that is1 they are themselves the source of light4 ,all other objects which do not produce light1 such as an apple1 a stone1 the ,earth and other planets and moons are called non-luminous bodies4 ,yet these non-luminous bodies can send out light if they are lighted up by some self-luminous body4 ,it is well that this is so1 or else we could never see anything that was not in itself giving out light4 ,if you will hold an apple or a stone in your hand and let the light of a candle or the ,sun fall on it you will be able to see the apple or stone1 and1 although you will hardly be able to notice it1 you will see them by the light which strikes them and is turned back1 or reflected from their surfaces1 as shown in ,fig4 #ada4 ,if a rubber ball is thrown on the sidewalk it will bounce back and this is just the way light acts when it strikes most objects--it bounces back1 or1 to use the right word1 it is reflected4 ,when we look at the surface of the ,earth by daylight we see the sand and stones1 grass and trees1 houses and other objects by the light which is reflected1 or thrown back from the surface of these things by the ,sun4 ,when we look at the surface of the ,earth by the light of the ,moon we also see the objects by reflected light1 but in this case the light is twice reflected1 for moonlight is the light of the ,sun falling on the ,moon and which is then reflected to the ,earth1 where it is again reflected to our eyes from the objects it falls on4 ,this is the reason moonlight is so pale when compared with sunlight4 ,illustration3 ,,fig4 #ada4--,,light ,,reflected ,,by ,,an ,,apple4 ,illustration3 ,,fig4 #adb4--,,light ,,refracted4 ,,spoon ,,in ,,glass ,,of ,,water4 ,refraction of ,light4--,when a beam of light passes through glass1 water and other transparent substances1 and is bent out of a straight line it is said to be refracted4 ,place a spoon in a glass of water1 as shown in ,fig4 #adb and it will look as if the spoon is broken in two at the point where it touches the water4 ,the bending of the beam of light will be more clearly understood from the drawing in ,fig4 #adc4 ,if you will look at a star squarely through a thick piece of glass and the star seems to change its position a little you will know that the sides of the glass are not quite parallel4 ,a prism is a three-sided piece of glass1 if we except the ends1 as shown in ,fig4 #add4 ,when a beam of light passes through a prism the prism affects the light in two ways3 first1 it bends the beam1 and second1 it separates the ether waves1 or light waves1 as they are called1 according to their lengths1 and as color depends on the length of the waves in the ether a prism will show the different colors on a screen and this is called the spectrum4 ,it is shown in ,fig4 #ade4 ,illustration3 ,,fig4 #adc4--;,,how ,,light ,,is ,,refracted4 ,illustration3 ,,fig4 #add4--,,prism4 ,lenses are pieces of glass having curved surfaces4 ,when a beam of light passes through a lens it is also bent out of its original direction1 or refracted4 ,a convex lens1 see ,fig4 #adf1 is a lens which is thicker in the middle than it is at the edges4 ,a convex lens is used for magnifying an object2 or for forming an image so that it can be magnified by another lens as in a telescope1 for forming an image on the screen of a camera1 and for bringing the heat waves of the ,sun to a focus1 as with a burning glass4 ,the point where the rays of light are brought together is called the focus4 ,you can easily find the focus of a lens by holding a sheet of paper1 or the hand under the lens and letting the sunlight pass through it2 where the spot of light is smallest and brightest there is the focus4 ,the distance of this point from the lens is called the focal length4 ,illustration3 ,,fig4 #ade4--,,prism ,,forming ,a ,,spectrum4 ,illustration3 ,,fig4 #adf4--;,,convex ,,lens4 ,a concave lens is a lens which is thinner at the middle than it is at the edge1 as shown in ,fig4 #adg4 ,it is used in small telescopes and opera glasses to turn the inverted picture formed by the convex lens around so that the object can be seen in its right position1 as shown in ,fig4 #aea4 ,shadows4--,shadows are useful as well as sunshine1 but shadows are such common1 everyday things it seems almost useless to talk about them2 still you may or may not know that there are different kinds of shadows4 ,illustration3 ,,fig4 #adg4--;,,concave ,,lens4 ,of course we all know that when a candle or a gaslight or the ,sun shines on an apple or any other opaque object--that is1 an object that will not let the ether waves go through it--the light is cut off back of it and this dark space is called a shadow2 this is also true when the ,sun shines on the ,earth1 or on any of the other planets or their moons4 ,there are always two parts to the shadow of an object unless the light is a mere point or the object is very close to the screen1 or surface on which the shadow falls4 ,the dark part of the shadow is called the umbra4 ,the edge of the object where the light and shade run together and form a partial shadow is called the penumbra and during a total eclipse this partial shadow surrounds the dark shadow1 or umbra of the ,earth or ,moon4 ,,chapter ,,ix ,,the ,,spyglass ,,or ,,telescope ,the ,boy ,who ,discovered the ,telescope4--,spectacles have been made and used for nearly a thousand years and the art of making lenses is very much older4 ,a little over three hundred years ago there lived in ,amsterdam1 ,holland1 a spectacle maker named ,lipperhey1 and it is said of him that he made good lenses4 ,there was apprenticed to this lens grinder a ,dutch boy1 and ,i am sorry ,i cannot tell you his name1 for he was a boy who did things2 but his name is not recorded1 which is a shame1 for if it had not been for this boy ,galileo might never have had a telescope4 ,one day while the boss was out this ,dutch boy was standing before a window of the shop and he held a lens before his eye with one hand and another lens before the first lens with his other hand1 as shown in ,fig4 #adh4 ,imagine his surprise when the church he was looking at seemed to move much nearer to him1 that is to say1 the image of the church was greatly enlarged4 ,the boy had made a wonderful discovery--he had discovered the telescope4 ,when his master returned the boy showed him what he had done and it was not long before the great ,galileo had a telescope and was startling the world by his wonderful discoveries of the moons of ,jupiter1 the rings of ,saturn1 the phases of ,venus1 the spots on the ,sun and a hundred other wonders of the sky4 ,a telescope is an arrangement of lenses in a tube for making the image of a distant object larger on the retina of the eye1 or1 as in the case of the fixed stars1 for making them brighter4 ,illustration3 ,,fig4 #adh4--,,lipperhey',s ,,boy ,,discovers ,,the ,,telescope4 ,the word telescope comes from two ,greek words1 the first1 tele1 which means afar1 and the second1 scope1 which means to see1 so that telescope means just what we should expect it to mean and that is to see afar4 ,there are several kinds of telescopes1 but there are only two kinds ,i want to make clear to you here2 in the first kind the eye sees the object just as it is1 that is1 standing right side up1 or erect4 ,this kind of a telescope is called a spyglass1 and is used to look at objects on the surface of the ,earth4 ,in the second kind of telescope the eye sees the object upside down1 or inverted1 and this kind of telescope1 which is called an astronomical telescope1 is just as good as the other for looking at the stars4 ,a ,pinhole ,telescope4--,before describing how to make and use real telescopes which have lenses ,i want to tell you of a little scheme to see afar1 and though it does not magnify the image of the object that is seen through it1 yet it aids the naked eye when you are looking at the ,sun and ,stars4 ,to make a pinhole telescope get a pasteboard tube about #a inches in diameter and #e or #f inches long4 ,a paper tube for mailing papers and sheet music is just the thing and can be bought at any stationery store4 ,illustration3 ,,fig4 #adi4--;,,disk ,,of ,,cardboard ,,for ,,pinhole ,,telescope4 ,illustration3 ,,fig4 #aej4--;,,cross ,,section ,,of ,,pinhole ,,telescope4 ,cut out a disk1 or circular piece of cardboard just large enough to fit the tube1 see ,fig4 #adi1 and push a pin point or needle through the center to make a small1 clean hole4 ,next1 glue this cardboard disk in the tube an inch from one end4 ,the disk must be glued in the tube so that no light can leak around the edge4 ,if1 now1 you look at the ,sun through the pinhole telescope1 as shown in ,fig4 #aej1 you will get a better view of it than if you look at it through a pinhole in the cardboard alone1 for the tube shuts out all the other rays of light from the eye4 ,to improve the seeing qualities of the pinhole telescope make the hole in the cardboard disk inch in diameter and cover this hole with a bit of tinfoil4 ,now make a hole in the center of the tinfoil with the point of a needle2 this makes the edge of the hole sharp4 ,a pasteboard tube without the pinhole will also aid the naked eye in seeing the ,moon and stars1 for it shuts out all the rays of light around the eye and limits the sight to a certain part of the sky2 together these things are very good helps in observing especially if there are gas and electric lights nearby4 ,illustration3 ,,fig4 #aea4--,,the ,,telescope 7,,galileo74 ,how a ,telescope ,works4--,a real telescope has at least two lenses in it2 the larger lens is placed in the end of the tube nearest the object to be viewed and is called the object glass because the light from the object is received by it4 ,the smaller lens is placed in the end of the tube nearest the eye1 and is called the eyepiece1 for it is this lens which enlarges1 or magnifies the image of the object that is thrown upon the retina of the eye4 ,there are two simple kinds of telescopes2 the first is the kind that ,galileo used for making his great discoveries4 ,the kind of lenses used and the way they are placed in the tube is shown in ,fig4 #aea4 ,in this telescope the object glass is a double convex lens and the beam of light which strikes it is brought to a point as in the case of a burning glass1 but before the light reaches this point it is caught up by the double concave lens which forms the eyepiece1 when it is carried to the eye in an erect position4 ,illustration3 ,,fig4 #aeb4--,,opera ,,glasses4 ,an opera glass is simply a pair of these little telescopes1 joined together so that they can be focused at the same time by means of an adjusting screw1 as shown in ,fig4 #aeb4 ,another simple telescope is formed of two double convex lenses4 ,as in the telescope just described the larger lens1 or object glass1 is placed in the end of the tube nearest the object to be viewed and the smaller lens1 or eyepiece1 is placed in the tube nearest the eye4 ,in this telescope1 though1 the eyepiece is a double convex lens and while a larger image is formed in the eye it is inverted1 or upside down1 so that this kind of a telescope is of no use as a glass to spy things with on the surface of the ,earth4 ,how to ,make a ,cheap ,telescope4--,lenses are absurdly cheap4 ,if you live in a large city you will find lens grinders who will sell you the kind of lenses you need for either kind of telescope for a dollar or so4 ,telescope ,no4 #a4--,this telescope is fashioned after an opera glass1 that is1 it has a concave lens for an eyepiece4 ,illustration3 ,,fig4 #aec4--,,pasteboard ,,mounting ,,of ,,lens4 ,illustration3 ,,fig4 #aed4--,,pasteboard ,,lens ,,mounting4 ,get two pasteboard tubes of the kind described for the pinhole telescope2 the bore1 or hole1 of the first tube should be #a inches in diameter and it should be #b inches long4 ,have the second tube a little smaller than #a inches in diameter on the outside so that it will slide easily into the larger tube and yet not leak light1 and have this tube #a inches long4 ,paint the inside of both tubes with black paint to keep the walls of the tube from reflecting any stray rays of light which may strike them4 ,the outside of both tubes can be covered with bookbinders' cloth to give them a neat appearance4 ,the next step is to mount the lenses4 ,the larger lens for the object glass is a double convex lens #a inches in diameter and having a #d-;inch focal length1 or focus1 as it is called for short4 ,a lens of this kind can be bought for #be or #cj cents4 ,the smaller lens for the eyepiece is a double concave lens #a inch in diameter and having a focus of #b inches4 ,this lens can be had for about #dj cents4 ,illustration3 ,,fig4 #aee4--,,opera ,,glass ,,telescope4 ,,cross ,,section4 ,cut a strip of thin1 tough cardboard inch wide and #f inches long2 on this strip glue a strip of heavy pasteboard inch wide and #e inches long1 and have one end of both pieces even1 as shown in ,fig4 #aec4 ,set a flatiron on the pieces and let them dry4 ,when dry make a groove down the middle of the heavy pasteboard by slicing out a very thin strip with the point of a sharp knife1 being careful not to cut through the thin cardboard4 ,now bend the strips around the lens with the lens in the groove1 glue over the thin end as shown in ,fig4 #aed1 and slip a a rubber band or tie a string around it to hold it in position until it has dried4 ,the small concave lens1 or eyepiece1 is mounted in the same way1 but since the lens is only #a inch in diameter1 cut the strip of cardboard inch wide and #d inches long and the strip of thick pasteboard inch wide and #c inches long2 this done glue them together1 cut the groove and mount the lens as before4 ,illustration3 ,,fig4 #aef4--,,telescope4 ,,cross ,,section ,,view4 ,the next and last thing is to smear glue on the cardboard mounts and push the convex lens in the end of the large tube and the concave lens in the end of the small tube4 ,now slide the tubes together and you will have as good a telescope as the boy who invented it4 ,it is shown in cross section in ,fig4 #aee4 ,you should1 however1 make two caps1 one for each end of the telescope to cover the lenses when not in use4 ,this little telescope is very handy to carry along on your scouting trips1 as it takes up so little room1 being only #b inches long when closed up4 ,telescope ,no4 #b4--,this telescope is very much better than the one just described for seeing the stars as it magnifies about #d times4 ,it is made exactly like the first one except that the larger tube is #ad inches long and the smaller tube is #e inches long4 ,in this telescope both lenses are double convex1 the large one1 or object glass1 having a diameter of #a inches and a focal length of #ab inches1 while the smaller lens1 or eyepiece1 has a diameter of #a inch and a focal length of #c inches4 ,it is shown in cross section in ,fig4 #aef4 ,a spyglass usually has four or five plano-convex lenses in it and these not only magnify the image but they also erect it so that you see the object as it really is4 ,while the homemade telescopes which ,i have described will not magnify as highly as a cheap telescope which you can buy1 yet you ought to make one1 for it will let you into the secret of combining lenses1 and this is as interesting as seeing the stars4 ,by all means make your first telescope and then if you want a better one buy it and get one as large as you can afford4 ,illustration3 ,,fig4 #aeg4--,,magnifying ,,power ,,of ,,telescope4 ,to ,find the ,power of a ,telescope4--,in the last chapter1 ,i explained what the focal length of a convex lens is1 see ,fig4 #adf1 and how to measure it4 ,to repeat1 it is the distance in inches between the center of a lens and the point where the rays come together4 ,you can find exactly what the magnifying power of your telescope is1 when both lenses are convex1 by dividing the focal length of the object glass by the focal length of the eyepiece1 or lens4 ,for instance1 suppose the focal length of the convex object glass of your telescope is #ab inches and the focal length of the convex eye lens is #c inches1 then #ab #c #d and the quotient #d is the magnifying power of your telescope4 ,to find the focal length of a concave lens is a little harder1 but ,garrett ,p4 ,serviss tells us in his good little book on ,astronomy with an ,opera ,glass of an easy way to judge the magnifying power of an opera glass and it is just the same for a telescope4 ,look at a brick wall through one of the tubes with one eye while the other naked eye sees the wall direct4 ,now notice how many bricks which the naked eye can see1 are needed to equal the thickness of one brick as seen through the glass4 ,the number of bricks seen with the naked eye represents the magnifying power of the glass4 ,fig4 #aeg shows how the bricks are compared4 ,the ,stars ,seen ,through a ,spyglass4--,the ,moon4--,when ,galileo lived the people believed that the ,moon was a ball as smooth and bright as a glass marble and they also thought that the dark spots on its surface were the continents of our ,earth reflected by it4 ,so the first thing ,galileo did when he got his telescope was to turn it on the ,moon1 for he wanted to know about these dark spots1 and you can imagine his surprise and delight to find that they were really great mountains and extinct volcanoes4 ,you cannot do better than to point your little homemade telescope at the ,moon1 stop1 look and rediscover the mountains on it and be as surprised and delighted as ,galileo was1 three hundred years ago4 ,to see the mountains at their best do not wait until the ,moon is full1 for the sunlight then shines directly on top of the mountains and there are no shadows to help the eye to gauge breadths and heights4 ,the best time to see the mountains is when the ,moon is in its first or its last quarter1 for then they are well brought out by the bright sunlight shining on them from the side and the black shadows which they cast on the other side4 ,the great smooth stretches seen on the ,moon are called seas4 ,it may be that in the long ago they were really seas1 but it is more likely that ,galileo and the early observers whose telescopes were little better than yours thought they were seas4 ,then there are huge cracks or gorges on the surface of the ,moon1 which start from some of the craters and run for hundreds of miles in every direction4 ,a number of these gorges start from a volcano named ,tycho 7pronounced ,ti-co7 and make the ,moon look as if it is cracked2 and it is likely that when the ,moon cooled down from its melted state after having been shot off from the ,earth it did crack in many places4 ,fig4 #aeh1 which is a good telescopic view of the ,moon1 shows some of these great cracks radiating from ,tycho4 ,illustration3 ,,fig4 #aeh4--;,,full ,,view ,,of ,,moon4 ,to show on a small scale how the ,moon cracked on cooling down ,nysmith filled a glass globe with cold water and then sealing the globe he plunged it into hot water4 ,the slow expansion of the cold water by the hot water caused the globe to crack as shown in ,fig4 #aei1 and by comparing the pictures it will be seen that the cracks on the ,moon and in the glass globe are very much alike4 ,there is a mountain called ,aristarchus#a 7pronounced ,ar-is-tar-cus7 which is believed to be formed of pure metal because it shines brighter than any other mountain on the ,moon4 ,its position is shown on the map1 ,fig4 #afj4 ,illustration3 ,,fig4 #aei4--;,,glass ,,globe ,,cracked4 ,the instant you look through your glass at the ,moon the man which shows so plainly to the naked eye vanishes like a coin in a magician's fingers and instead you will see a new world covered with plains and mountains4 ,but if you will look at the ,moon when it is nine or more days old1 you will see with the aid of your glass and a little imagination the ,moon girl1 as shown in ,fig4 #afa4 ,you should have no trouble in finding her1 for the ,apennines form her crown while ,tycho shines upon her breast like a great yellow diamond4 ,footnote #a3 ,aristarchus was a ,greek who lived #bjj years before ,christ4 ,he taught that the earth was round4 ,illustration3 ,,fig4 #afj4--,,map ,,of ,,the ,,moon4 ,illustration3 ,,fig4 #afa4--,,the ,,moon ,,girl4 ,there is another crater mountain which you should by all means know and that is ,copernicus#b 7pronounced ,ko-per-ni-kus74 ,look through your glass at the southeastern end of the ,apennines and you will see a crater that is larger in diameter than ,tycho1 though it is not so deep4 ,tycho1 ,copernicus and the ,apennines will serve you well as landmarks if you follow up the explorations of the ,moon which you have so well begun4 ,footnote #b3 ,copernicus--,polish1 astronomer4 ,born #adgc4 ,before his time it was believed that the ,sun1 ,moon and stars revolved round the ,earth4 ,copernicus showed that the ,earth was a planet and1 with the others1 that it revolved round the ,sun4 ,the ,sun4--,you can see the spots on the ,sun quite well with your glass1 and sunspots are always interesting4 ,do not try to look at the ,sun through your glass without covering the eyepiece either with a thickly smoked or dark-colored glass4 ,you must also use smoked or colored glasses over your eyepiece when you are looking at an eclipse of the ,sun4 ,you should look for sunspots this year1 #aibj1 for they are decreasing in number and size and in a few years there will be scarcely any4 ,after that there will be more of them again4 ,the ,planets4--,after you have seen the mountains on the ,moon and the spots on the ,sun you should next turn your glass on the planets4 ,while you will probably say that the planets loom up very small--the largest1 ,jupiter1 appearing about the size of the head of a large pin--yet they are wonderful to look at even through the smallest telescope4 ,mercury4--,this is a planet not easy to see even with the aid of a glass so if you see it you can think that you are lucky or skillful or perhaps a little of both4 ,venus4--,venus can be seen very much better with your small glass than ,mercury1 but you will only be able to see it as a little disk and not as a crescent for your glass is of too low a magnifying power4 ,it is a brilliant object though even through the smallest glass4 ,mars4--,while you cannot see the canals of ,mars with your glass you can see it as a bright disk of light and this is well worth while4 ,mars is believed to be peopled and the thought that it may be makes it a mighty interesting object to look at4 ,look at it through your glass and think it over4 ,jupiter4--,on account of his great size you will be able to see ,jupiter better than any of the other planets4 ,his disk will show clear and distinct and if you have good eyesight and your glass is fairly good you will be able to see one and perhaps two of his nine moons which will appear as little points of light close to the planet4 ,saturn4--,the rings of ,saturn cannot be seen with a glass magnifying less than four times4 ,his rings are at this writing 7#aiae7 in the best position to be seen as the flat side of the rings is toward us now4 ,in #aiba the edge of his rings will be in a line with the ,earth and then it will be very hard to see them even with a much larger telescope4 ,uranus4--,although ,uranus is so very far away1 it can be seen with your glass1 though you may not be able to see it as a disk of light4 ,you can tell when you have found ,uranus by watching it for a few nights4 ,if it changes its position among the stars around it you will know you are looking at ,uranus4 ,neptune4--,neptune is farther away than ,uranus and your glass will show it as a mere point of light4 ,like ,uranus you will know it if you see it1 by its motion among the stars4 ,the ,stars4--,after you have looked at the ,sun1 ,moon1 and planets to your hearts' content turn your glass on the ,big ,dipper and you will see about ten times as many stars as you can see with the naked eye4 ,the ,big ,dipper is full of starry surprises as you will find to your pleasure on looking at it with your glass3 for instance1 instead of the handle being formed of three stars1 it blazes with dozens of them4 ,take a look at ,alcor1 which is the middle star in the handle of the ,dipper4 ,you may remember ,i told you in the first chapter that it had a little companion1 ,mizar1 which only sharp eyes can see4 ,now look at ,alcor through your glass and you will see that it and ,mizar are quite widely separated4 ,the ,north ,star is also a double star as these twin stars are called4 ,just as ,mizar is a good test for the naked eye so the twin of the ,north ,star is a good object on which you can try out the seeing power of your glass4 ,another double star which some boys can separate with their keen naked eyes is ,epsilon1 named after one of the ,greek letters 7,see ,appendix ,c74 ,this star together with ,vega1 a very bright and beautiful blue star of the first magnitude1 and ,zeta1 another ,greek letter star1 form a triangle1 which is the constellation of ,lyra4 ,whether or not you can separate ,epsilon into two stars with the naked eye1 you will see them stand out separate and distinct through your glass4 ,if you had a more powerful glass you would see that each of the stars of ,epsilon has a faint companion star1 so that it is really a quadruple star1 that is1 there are four stars right together4 ,then there is the ,milky ,way1 always a wonderful sight to the naked eye1 but still more wonderful when viewed through a glass however small2 there are the stars of the ,pleiades of which the eye sees not more than six or seven without help1 but which bursts forth like a skyrocket into a cluster of many-colored lights when seen through a glass2 these are only a few of the hundreds of other things which you can see in the sky with the help of your little telescope4 ,,chapter ,x ,,the ,,time ,o' ,,day ,what ,time ,is ,it8--,this is a question everybody is always asking everybody else4 ,did you ever stop to think what a curious thing time is8 ,no one knows when it began nor can anyone tell when it will end1 yet we measure off a little bit from that which has gone or from that which is yet to come1 so that we may know when to eat1 to start to work1 or to quit1 and when to go to bed or to get up4 ,we know that1 roughly1 a year is the time it takes the four seasons to come and go1 and that this is done when the ,earth travels once round the ,sun2 that the month is based on the time it takes the ,moon to travel once round the ,earth2 that the week has nothing to do with the ,sun1 ,earth1 ,moon or ,stars1 but is a pure invention1 and1 finally1 that the day is the time it takes the ,earth to turn once round on its axis4 ,but when we want to know what time it is we mean1 of course1 what the hour1 the minute and1 sometimes1 even the second of the day is1 and these are the small measured parts of time we want to find out about4 ,the time it takes the ,earth to make one complete turn on its axis is divided naturally into two parts1 more or less equal1 depending on where we live1 and these parts are daytime and nighttime4 ,this general division of time1 marked by alternate daylight and darkness1 may have served every need of the cave man at first1 but just as he came to have sense enough to crawl into his cave to get out of the rain so the blazing ,sun must finally have driven into his awakening brain its use to him as a means of marking time4 ,as his savage mind grew less animal and more human1 ideas were formed in it either by instinct or by the first vague glimmerings of reason and he began to think4 ,he saw that when the light of the ,sun fell on the trees and the rocks1 long1 strange1 black marks1 which we call shadows1 were cast by them1 and he must have noticed that the shadows swung round the trees and rocks in the opposite direction to the way the ,sun was traveling4 ,to mark off with his eye and place a stone at a point somewhere near the middle of the shadow cast by the rising ,sun and that cast by the setting ,sun1 and which would mean that the day was half done was the next great step4 ,these things were1 quite likely1 the first feeble efforts of the human race to measure time1 and out of which the sundial came1 as well as the crude beginnings on which the science of astronomy is based4 ,solar ,time1 or ,time by the ,sun4--,to make a sundial which would give correct ,sun time was so hard a problem that men had to think about it for a million years before they could solve it and the chances are that then it was invented by a boy4 ,you will find directions for making a simple sundial in ,chapter ,,iii4 ,now let's find out how we can know when a day begins and when it ends4 ,on first thought this would seem to be an easy thing to do and it is if we are not particular about being exact4 ,you will remember that a day is measured by the time it takes the ,earth to turn once round on its axis and what we want to know1 now1 is how to tell when the ,earth has made one complete turn1 no more and no less4 ,we can tell this1 you may say1 by a clock or a watch1 but the best of clocks and watches are always a little fast or a little slow1 and time today is measured by the fraction of a second4 ,so we get the apparent time from the ,sun1 change it into mean time and set our clocks and watches by it4 ,there are several ways by which we can obtain ,sun time1 but all of them are based on the same principle4 ,the way that was used by people who first began to think about these things1 and it is also a good way for you to try1 is like this3 ,illustration3 ,,fig4 #afb4--;,,diagram ,,showing ,,how ,,to ,,find ,,solar ,,noon4 ,first you must have a good horizon1 that is1 you must be able to see the ,sun rise and set without any mountains or other things in the way4 ,when you begin your observations for getting solar time note exactly where the ,sun rises and where it sets on the horizon4 ,you can easily do this by using hills1 houses and trees for marking the places4 ,now with your eye draw a line between these two points4 ,notice also where you are standing and let your line of sight meet the imaginary line which joins the places where the ,sun rises and sets just as near the middle as you can1 and all of which is clearly shown in ,fig4 #afb4 ,now this line will run due north and south and hence it is a meridian line which you are to use to observe the ,sun4 ,when the ,sun reaches that point in the sky where it is directly over the middle of the imaginary line1 joining the places where it rises and sets1 it is exactly noon1 ,sun time4 ,the next day observe the ,sun in the same way and when it crosses the meridian line again the ,earth will have turned round once and you will have a part of time measured off called a ,sun or solar day4 ,when the time is taken between two succeeding crossings of a meridian by the ,sun a day so measured is called by astronomers an apparent solar day1 and when the ,sun is on the meridian it is called apparent noon4 ,now the word apparent means to seem1 that is1 something which is obtained by observation4 ,an apparent solar day is then the length of a day measured by the ,sun1 and while we might suppose that the ,sun at least would always give a day of the same length1 this is not the case for the reason that the ,earth does not travel in all parts of its orbit round the ,sun at the same rate of speed1 and1 further1 it is tilted on its axis2 together these things make the days as measured off by the ,sun unequal and hence they are called apparent solar days4 ,mean ,solar ,time4--,apparent solar days which are of unequal length were all right as long as sundials were the only timepieces1 but when clocks and watches came into use days which were equal in length were needed and needed badly1 for a clock couldn't be made which would keep ,sun time4 ,so astronomers who watched the stars by night lay awake during the day wondering how they could make the ,earth travel round the ,sun at the same speed every day in the year and just as though it was not tilted4 ,at last they solved the problem4 ,and how do you think they did it8 ,it was as easy as rolling off a log--when you know how4 ,they simply imagined that the ,earth traveled at a uniform speed and that it stood straight1 as shown in ,fig4 #gd4 ,in other words they took the mean length1 which is another way of saying the average length of all the apparent solar days which make up a year1 and divided it up equally4 ,further1 the men who got up this scheme said that every day should have not only the same length1 but that it should have #bd hours1 and of course you know that hours are divided into minutes and minutes into seconds4 ,mean solar time1 then1 is really imaginary ,sun time and this is the time used everywhere and watches and clocks are set by it4 ,equation of ,time4--,to get the exact mean time each day you have to know just what the apparent solar time is1 and then you have to know what the difference in time is between the apparent solar time and the mean time1 that is how many minutes and seconds to add to or subtract from the solar time of each day to get the mean time4 ,this difference of time is called the equation of time4 ,a table prepared by ,professor ,todd of the ,amherst ,college ,observatory is given in ,appendix ,m and can be used for all ordinary purposes4 ,standard ,time4--,a meridian1 as you know1 is an imaginary line running due north and ,south and hence we can have a meridian whenever we want it and as many as we like4 ,when the ,sun crosses the meridian of those who are on it1 it is noon to them1 but to no one else1 for the ,sun has already crossed the meridians to the east of it and has yet to cross those to the west of it4 ,when the ,sun crosses the meridian which passes through ,new ,york ,city it is noon there and when the ,sun crosses the meridians which pass through ,st4 ,louis1 ,denver and ,san ,francisco1 it is noon at those places1 and this is true of every other place and of every other hour of the day4 ,this is the reason why every place had its own1 or local time1 before the year of #ahhc4 ,as an illustration it takes the ,sun about three hours to cross the ,united ,states from the ,atlantic to the ,pacific coasts4 ,now as long as people traveled on foot1 or by horse1 they moved so slowly that local time did not worry them1 but when railroads came into use there was all kinds of trouble for the traveler2 if he was going west his watch was faster than the local time of the towns he passed through and if he was going east his watch was always slower than the local time4 ,if he wanted the right time he had to set his watch at every town he passed through2 of course he couldn't very well do this and he was always in a stew4 ,the railroad companies were just as much put to for it was next to impossible to make a timetable to fit the local time of each town and still keep up a running schedule2 and the result was that the railroads finally got up a system of their own which they called railroad time4 ,this was all well enough for everybody but the poor traveler1 who1 not knowing the difference in time between local time and railroad time1 nearly always found he was either an hour too early or--as it usually happened--a minute or two too late to catch his train4 ,as new towns sprung up and railroads multiplied1 things had come to such a pretty pass in #ahhc that nobody but the astronomers knew what the real time was1 and they wouldn't tell2 then a new time scheme was tried out1 and as it is still used we must conclude it is a fairly good one4 ,it is called the zone1 or belt system of standard time2 the time used is called standard time because the towns and cities and railroads all use it and there is no confusion4 ,to understand what standard time means we have to know first what a standard meridian is4 ,a meridian1 as we have said1 is an imaginary line running due north and south anywhere we want it1 but while a standard meridian is also a line running due north and south it has a fixed position4 ,the first fixed or prime meridian1 as it is called1 passes through ,greenwich 7pronounced ,gren-ij71 which is a part of ,london1 ,england4 ,the reason this meridian was chosen by geographers to reckon distance east and west from is because the ,royal ,observatory at ,greenwich is one of the oldest in the world and it was the first from which exact time was sent out4 ,if a circle is divided into #cfj degrees1 as shown in ,fig4 #afc1 and it is also divided into #bd parts1 each part will be a space equal to #ae degrees or #a hour4 ,now geographers have divided the ,earth into #bd equal parts by meridians separated by #ae degrees1 and each space1 or belt1 between them represents #a hour1 as shown in ,fig4 #afd4 ,these fixed meridians start at the first1 or prime meridian1 at ,greenwich and all the other meridians are measured in degrees east or west of ,greenwich as the case may be4 ,illustration3 ,,fig4 #afc4--;,,circle ,,divided ,,into #cfj ,,degrees ,,and #bd ,,hours4 ,starting west from the first1 or prime meridian1 which passes through ,greenwich the time at the second standard meridian1 which is called the #aeth meridian because it is #ae degrees from the first meridian1 will be one hour behind ,greenwich time4 ,at every standard meridian the mean solar time is used as the standard time and every place on it and halfway to the meridian on both sides uses it1 and so local time and standard4 ,this makes it very convenient for the traveler1 for instead of setting his watch at each station he does not need to set it until he has traveled #ae degrees east or west1 which is about #gjj miles in our northern latitudes1 and then he turns it exactly one hour ahead or one hour back1 depending on the direction he is going4 ,illustration3 ,,fig4 #afd4--,,the ,,earth ,,divided ,,into #bd ,,standard ,,meridians4 ,there are four standard time meridians running through the ,united ,states1 as shown in the map in ,fig4 #afe4 ,the one running through ,new ,york1 ,pennsylvania1 ,new ,jersey and ,delaware is the #geth meridian1 meaning of course that it is #ge degrees west of the prime meridian which passes through ,greenwich4 ,time on this meridian and halfway to the meridians on both sides of it is called ,eastern ,time4 ,it is just five hours slower than ,greenwich time4 ,illustration3 ,,fig4 #afe4--,,standard ,,time ,,meridians ,,in ,u4 ,s4 ,the next is the #ijth meridian and this one passes through ,wisconsin1 ,illinois1 ,missouri1 ,tennessee1 ,mississippi and ,louisiana4 ,time on and around this meridian is called ,central ,time4 ,the one after this is the #ajeth meridian and passes through ,montana1 ,wyoming1 ,colorado1 ,new ,mexico and ,texas4 ,time on and around this meridian is called ,mountain ,time4 ,the last of the four meridians1 the #abjth1 passes through the ,states of ,washington1 ,oregon and ,california and time on and around this one is called ,pacific ,time4 ,it is three hours slower than ,eastern time and #h hours slower than ,greenwich time4 ,although these meridians are just one hour apart the time is not changed on them nor exactly in the middle of a belt but at some well-known town or city between two of the meridians1 as you will see by looking at the map1 ,fig4 #afe4 ,fig4 #aff shows the standard time at different cities around the world north of the equator4 ,star or ,sidereal ,time4--,besides all the different kinds of time described above there is still another and a very important kind of time1 and this is obtained by the stars4 ,just as ,sun1 or solar time is obtained by noting when the ,sun crosses a meridian1 so star1 or sidereal time is obtained by observing when a star crosses a meridian4 ,now there is a difference between the length of a day when formed by the ,sun crossing the meridian twice in succession and when formed by a star crossing the meridian twice in succession4 ,this difference in time1 between a solar day and a sidereal day1 as they are called1 is nearly four minutes4 ,but the point is this3 an astronomer can obtain the time from watching a star cross the meridian much more accurately than he can from the ,sun1 because a star is a mere point of light1 and it is easier for him to calculate the mean solar time from the transit of a star than it is for him to go to bed1 and besides he would rather do it1 too4 ,how ,time ,is ,distributed4--,in this country the correct standard time is sent out by the ,united ,states ,naval ,observatory at ,washington to all cities east of the ,rocky ,mountains1 by wire telegraph1 and all over the ,atlantic ocean and seaboard by wireless telegraph4 ,illustration3 ,,fig4 #aff4--,,standard ,,time ,,at ,,different ,,cities4 ,when time is received over the wires from ,washington it is distributed by local telegraph or by time balls to various jewelry stores and to private citizens who always want to be set right4 ,how an astronomer gets the correct time2 how it is sent out over the wires and by wireless and how it is distributed to the common people is a mighty interesting piece of business4 ,briefly it is like this3 ,how ,correct ,time ,is ,obtained4--,every observatory has1 besides its big telescopes1 a transit instrument1 a wonderfully accurate clock1 and a clockwork device called a chronograph4 ,the transit instrument is nothing more than a telescope with a thin piece of clear glass with a number of lines ruled on it with a diamond1 about inch apart1 and this ruled glass is set between the eyepiece and the object glass1 as shown in ,fig4 #afg4 ,illustration3 ,,fig4 #afg4--,,ruled ,,glass ,,in ,,transit ,,instrument4 ,this telescope1 or transit instrument--so called because it is used to observe the transit1 or passage1 of a star across a meridian--is set on an axis so that the telescope can be pointed to any place on the meridian but it cannot be moved east or west4 ,sometime before a star is due to cross the meridian the astronomer sets his transit instrument so that the star will pass right across the line of sight of his telescope4 ,the purpose of observing the transit1 or passing of a star is to see how much his wonderfully accurate clock has lost or gained during the past #bd hours4 ,so his clock is right at hand4 ,the chronograph is another accurate clockwork which revolves a cylinder about the size and shape of a phonograph cylinder1 and around which is wrapped a sheet of white paper4 ,this cylinder makes one revolution every minute4 ,a fountain pen marks a spiral line on the paper when the cylinder is revolving but at every second the pen is thrown out of position and this makes a notch in the line4 ,after starting the chronograph the astronomer takes an electric push button1 which is connected with and controls the lever which holds the pen of the chronograph that makes the notches1 and takes up his position with his eye at the end of the transit instrument4 ,the instant he sees the star on one of the lines in the telescope he presses the button and this closes the electric circuit and makes a big notch in the line traced on the paper of the chronometer4 ,from the position of the big notches which he caused to be made on the paper as the star crossed the ruled lines1 and the little notches made regularly every second1 he can dope out just how much his clock is in error--that is1 how much it is too fast or too slow4 ,the next thing he does is to change this absolutely correct star time into mean solar time1 when it is ready to be sent all over the ,united ,states east of the ,rocky ,mountains by telegraph4 ,the ,pacific ,coast folks get their correct time from a ,government observatory at ,mare ,island in ,san ,francisco ,bay4 ,how ,time ,is ,sent by ,telegraph4--,the wires of the ,western ,union ,telegraph ,company run into the ,united ,states ,naval ,observatory at ,washington1 and for a few minutes each day all of this company's wires are controlled by the ,government4 ,about five minutes before #ab o'clock noon1 standard time at ,washington1 each day the wires all over the country east of the ,rockies are cleared and all business and other messages are cut off for the time signals4 ,at five minutes of #ab sharp the ,united ,states ,naval ,observatory begins to send the beats of every second of the wonderfully accurate observatory clock1 which are ticked out on telegraph sounders in all the cities and towns4 ,but no1 not every beat1 for the #bith second of each minute1 the last #e seconds of each of the first #d minutes1 and then the last #aj seconds of the last minute are not sent4 ,the first click of the sounder after the #aj second rest is the noon signal1 and all local clocks are set by it4 ,in many cities the telegraph company has special wires running to various jewelry and other stores and these subscribers get the correct time direct by telegraph from the ,naval ,observatory for their sounders are connected in the regular line circuit4 ,the ,time ,ball4--,the ,bureau of ,navigation got up what is known as the time ball for the benefit of sailing masters in particular and the townsfolk in general4 ,illustration3 ,,fig4 #afh4--,,the ,,time ,,ball4 ,in ,new ,york and other cities along the seacoasts and lake ports a great ball1 weighing in the neighborhood of #ajj pounds1 having a diameter of over #c feet and with a hole in its center1 is slipped over a pole or flagstaff some #bj feet in height1 which is mounted atop of some high building where it can be seen to the best advantage4 ,the ball is held in position at the top of the pole by an electro-mechanical trigger1 which is placed directly in the electric telegraph circuit that runs into the ,naval ,observatory at ,washington4 ,when the time signals are being sent out from the observatory and the telegraph key is closed at exactly noon the trigger which holds the ball in place is released by the current and the ball drops4 ,fig4 #afh shows a time ball atop of the old ,western ,union ,building in ,new ,york4 ,illustration3 ,,fig4 #afi4--,,receiving ,,time ,,signals ,,by ,,wireless4 ,how ,time is ,sent by ,wireless4--,at ,arlington1 ,va41 just across the ,potomac ,river from ,washington1 is one of the most powerful wireless stations in the world1 having a sending range of at least #c1jjj miles4 ,every day at noon time signals like those sent over the wires on land are sent out so that every navigation officer and sailing master whose ships are fitted with wireless apparatus can get the correct time4 ,all over the ,atlantic seaboard boys1 as well as jewelers 7see ,fig4 #afi71 have wireless receiving sets and they receive the correct time every day by wireless free of charge4 ,no license is required to receive wireless signals1 the cost of the apparatus is little and the experience immense4 ,are you in on it8 ,,chapter ,,xi ,,the ,,stars ,,of ,,the ,,zodiac ,zodiac6--,it sounds to the untrained ear like the password of a bomb-thrower or a first cousin to a dish of ,hungarian goulash4 ,it is enough1 albeit1 to scare even a ,scout away from the stars1 but be not afraid1 for it can't hurt you and you can't eat it4 ,on the other hand1 if you are on speaking terms with the zodiac 7pronounced zo-di-ak71 it will help you to find the planets and at the same time you will add enough new constellations to those you already know to give you a high passing mark for a merit badge in the ,boy ,scouts if you want one4 ,besides1 the signs and constellations of the zodiac will aid you to use the almanac and help you in many other ways4 ,you have often noticed that the ,sun seems to travel through the sky over a path or belt that is always the same from west to east2 you must have noticed1 too1 that the path of the ,moon is almost the same as that of the ,sun1 but you may or may not remember that the planets also travel over the same path as the ,sun and ,moon4 ,it is just as though the ,sun1 ,moon and planets moved at different speeds on an endless belt in the sky which runs round the ,earth nearly in a line with its equator1 though tilted at a slight angle to it1 and this line is called the ecliptic4 ,the way the ancients thought it was and the way it really looks to us is shown in ,fig4 #agj4 ,the ancients called this apparent path of the ,sun1 ,moon and planets with the stars for a background the zodiac1 so it is not such a horrible specimen after all4 ,we know1 of course1 that the ,sun is the center of our solar system and that the planets1 including the ,earth and ,moon1 are at various distances from the ,sun and that each moves in a path1 or orbit1 of its own1 making a small angle with the ecliptic4 ,what we call the ,zodiac takes in all these orbits and is1 therefore1 a belt of considerable width through the center of which runs the ecliptic4 ,illustration3 ,,fig4 #agj4--,,the ,,zodiac ,,as ,,invented ,,by ,,the ,,ancients4 ,illustration3 ,,fig4 #aga4--,,the ,,zodiac ,,as ,,we ,,know ,,it ,,today4 ,suppose we draw a little circle and call it the ,sun1 as shown in ,fig4 #aga1 and draw an ellipse around it and call it the ,earth's orbit1 putting on another little circle for the ,earth2 now suppose we draw a much larger ellipse round the one representing the ,earth's orbit1 divide it into #ab parts and put a constellation in each part4 ,knowing now that the ,sun1 ,moon and planets are very near the ,earth when compared with the fixed stars it must be plain that these bodies when seen from the ,earth1 which is always changing its position in its travels round the ,sun1 would appear to move in and across the constellations4 ,take a look at ,jupiter some night when he is moving across any of the constellations and he will seem to be a part of it2 this is the reason we speak of the ,sun or a planet as being in a certain constellation at a given time4 ,the stars forming the background of the ,moon and the planets can always be seen1 for we are then looking at them from the dark side of the ,earth1 but they cannot be seen when they form the background of the ,sun1 for the stars are on the other side of him when he gets between us and them and he shines in our eyes4 ,these constellations through which the ,sun1 ,moon and planets seem to pass1 or as the almanacs say are in1 lie in a belt formed by the path of the ,sun and neither the ,moon nor the planets ever get farther from the path of the ,sun than #h degrees on either side of him and this belt is called the zodiac4 ,the belt1 or zodiac1 is divided into #ab equal parts1 or spaces1 which were called signs by the ancients and they are still called signs4 ,this makes the length of each sign1 or space1 #cj degrees1 and hence the #ab signs1 which are called the ,signs of the ,zodiac1 equal #cfj degrees or a complete circle4 7,see ,chapter ,x1 ,the ,time o' ,day47 ,the ,signs of the ,zodiac and the constellations of the ,zodiac have the following names3 ,aries1 the ,ram2 ,taurus1 the ,bull2 ,gemini1 the ,twins2 ,cancer1 the ,crab2 ,leo1 the ,lion2 ,virgo1 the ,virgin2 ,libra1 the ,balance2 ,scorpio1 the ,scorpion2 ,sagittarius1 the ,archer2 ,capricornus1 the ,goat2 ,aquarius1 the ,water ,bearer1 and ,pisces1 the ,fishes4 ,it is in one of these constellations that the ,sun1 ,moon and planets are always to be found4 ,a good way to find any one of the constellations is by knowing the time when it will be on your meridian1 that is the line over your head due north and south1 during a given month4 ,any constellation of the zodiac will be on your meridian at #i o'clock ,p4 ,m41 during the month given opposite its name in the following table3 ---------------------------------------- ------------------------- ,time ,constellation ,astronomical ,how ,pronounced ,common ,names will ,appear on ,your ,names ,meridian at #i ,p4 ,m4 ---------------------------------------- ------------------------- ,aries ,a-ri-es ,the ,ram ,december ,taurus ,tau-rus ,the ,bull ,january ,gemini ,gem-i-ni ,the ,twins ,february ,cancer ,can-cer ,the ,crab ,march ,leo ,le-o ,the ,lion ,april ,virgo ,vir-go ,the ,virgin ,may ,libra ,li-bra ,the ,balance ,june ,scorpio ,scor-pi-o ,the ,scorpion ,july ,sagittarius ,sag-it-ta-ri-us ,the ,archer ,august ,capricornus ,cap-ri-cor-nus ,the ,goat ,september ,aquarius ,a-qua-ri-us ,the ,water ,bearer ,october ,pisces ,pis-ces ,the ,fishes ,november ---------------------------------------- ------------------------- ,to find any constellation during any other month than that given in the last column above subtract two hours for each following month4 ,suppose you want to find ,aries1 the ,ram1 in ,january instead of ,december1 look for it on your meridian at #g ,p4 ,m42 in ,february look for it at #e ,p4 ,m41 and so on4 ,you will of course come to a month where the constellation will run into daylight and then you won't be able to see it again until the ,earth has traveled round the ,sun to a point where the ,earth is again between the ,sun and the constellation4 ,the constellations of the zodiac are shown in ,fig4 #agb2 also the symbol for each sign and the month in which the sun enters the sign4 ,as we shall later explain1 the constellation is no longer in the sign of the same name4 ,if you look southward at the sky some night for any particular constellation you need not expect the stars which form it to stand out separate and distinct1 as shown in ,figs4 #agb and #agd2 if you do you will be sadly disappointed1 for many of the constellations of the zodiac are hard to recognize compared with the ,big ,dipper1 or ,orion1 or ,pegasus4 ,illustration3 ,,fig4 #agb4--;,,constellations ,,and ,,signs ,,of ,,the ,,zodiac4 ,nor are the constellations of the zodiac as equally spaced in the sky as in ,figs4 #agb and #agd4 ,some of the stars are very scattered and stretch over part of two signs of the zodiac1 while others do not take up nearly all the space allowed them2 ,figs4 #agb-agd are but rough sketches4 ,to recognize these constellations you will have to use a good star map4 ,the heavy black line drawn lengthwise through the middle of the strip in ,fig4 #agb represents the line of the ecliptic which is the yearly path the ,sun seems to take4 ,the planets also take the same course1 though they may be on one side or the other of the ,sun's path by #h degrees1 thus making the zodiac #af degrees wide2 hence1 the lighter parallel lines on either side of the black line1 or path of the ,sun1 is the farthest away that the planets ever get4 ,if you were to cut the strip of paper1 ,fig4 #agb1 out of the book and paste the ends together1 you would have a band1 or circle representing the zodiac more nearly as it is2 but instead of cutting the book you had better draw the signs and constellations on a strip of cardboard #b inches wide and #bd inches long and glue the ends together1 as shown in ,fig4 #agc2 you will now have a zodiac with which you can do a little experimenting4 ,illustration3 ,,fig4 #agc4--;,,cardboard ,,zodiac4 ,place a candlelight in the center of the cardboard ring and suspend a marble from a thread1 by means of a drop of sealing wax1 and let the marble hang between the light and the cardboard zodiac4 ,as seen from the marble1 which represents the earth1 the candle1 representing the sun1 is in the constellation directly opposite the one in which the shadow of the marble falls4 ,in the almanacs our year begins with ,january and as the ,sun is then in the sign ,aquarius1 this month is represented by a picture of ,aquarius1 the ,water ,bearer2 but in marking out the signs of the zodiac on a flat strip of paper we begin with ,aries1 which the ,sun enters in the month of ,march1 and read them from right to left4 ,the reason for this is because the ,earth travels round the ,sun counter-clockwise as seen from the north and this makes the ,sun appear to move eastward through the constellations of the zodiac4 ,illustration3 ,,fig4 #agd4--;,,constellations ,,of ,,zodiac ,,in ,,circle4 ,this makes all the months follow each other in the proper order when the strip of paper is glued together1 as shown in ,fig4 #agc1 or when the constellations are arranged in a circle1 as shown in ,fig4 #agd4 ,this latter diagram shows plainly that when the ,earth is at that part of its orbit marked ,a the constellation of ,taurus is back of the ,sun4 ,if we are on that side of the ,earth which is toward the ,sun of course we cannot see ,taurus for the ,sun1 which is shining in our eyes4 ,still ,taurus is the background of the ,sun just the same1 and so when the almanac says the ,sun is in ,taurus you will know that the ,sun is directly between the ,earth and ,taurus4 ,the same thing is true of all the planets4 ,take ,mars1 for example2 whenever ,mars is in that part of its orbit so that we can see it at night1 as shown at ,b1 ,fig4 #agb1 we also see the constellation back of it--in this case it is ,libra1 the ,balance--and since a planet and a fixed star look exactly alike to the naked eye it is easy to think of ,mars as being in that constellation2 and it is the same with all the other planets4 ,the ,constellations of the ,zodiac4--,the ,constellations of the ,zodiac and the ,signs of the ,zodiac are two very different things4 ,long ago1 when the zodiac was invented1 the constellation of ,aries1 the ,ram1 was in the first of the #ab spaces and he and the sign of this space were of course at that time the same4 ,owing to a peculiar motion of the ,earth1 called precession1 the signs of the zodiac have moved backward during the last #b1jjj years and the sign of ,aries1 which used to be in the constellation of ,aries1 is now in the constellation of ,pisces1 the ,fishes4 ,illustration ,aquarius1 the ,water ,man4--,a constellation of autumn3 ,aquarius is always pictured in the almanacs as pouring water from a pitcher4 ,all the stars of this constellation are faint and scattered and none of them are in a line with the ecliptic4 ,aquarius got his name from the ,romans1 who called him the ,waterman because when the ,sun enters the sign ,aquarius in ,january there are usually heavy rains in ,italy and in the long ago people thought the stars had a lot to do with the weather1 and everything else on ,earth1 for that matter4 ,illustration3 ,,fig4 #age4--;,,constellations ,,of ,,aries ,,the ,,ram4 ,pisces1 the ,fishes4--,this constellation is now in that part of the zodiac whose sign is 7,aries74 ,it is not an interesting constellation to look at with the naked eye1 for its stars are faint and they stream out in two lines over nearly two signs of the zodiac4 ,but ,pisces is none the less a very important constellation because it is at one of the points where the line of the equator crosses the line of the ecliptic4 ,when the ,sun crosses the point where the equator and the ecliptic meet the days and nights are then equal at all places on the ,earth1 and hence we call this time of the year1 which is about the twenty-first of ,march1 the equinox1 which means equal days2 or the vernal equinox1 which means equal spring days4 ,illustration ,aries1 the ,ram4--,this constellation used to be in that part of the zodiac whose sign is 7,aries7 but is now in that part whose sign is 7,taurus74 ,illustration ,the position of ,aries in the sky is shown in ,fig4 #age and you can easily find him by drawing a line from the ,north ,star to ,alpha in ,pegasus and another line at right angles to the first line until you come to two bright stars quite close together and a third one not quite so bright4 ,these are the chief stars of the constellation of the ,ram4 ,illustration ,taurus1 the ,bull4--,this constellation is now in the sign 7,gemini71 of the zodiac4 ,in ,chapter ,,ii you will find directions for locating ,taurus4 ,you will remember that the red star ,aldebaran forms the right eye of the ,bull4 ,the little group of stars called the ,hyades is the ,bull's face and the ,pleiades are in his shoulder4 ,gemini1 the ,twins4--,it is easy to see why the ancients called this constellation of the zodiac the ,twins1 for its two chief stars1 ,castor and ,pollux1 are quite close together and while of different colors they are of about the same brightness4 ,these two stars are the heads of the ,twins and four other stars are their feet and these stand forever on the ,milky ,way4 ,the ,twins are easily found since they are next to ,taurus1 the ,bull4 ,illustration ,gemini is an important constellation1 as the ,sun reaches its most northern point in it in summer2 this is called the summer solstice1 and takes place about ,june #ba4 ,when the ,sun has reached this point it casts the shortest shadow at mid-day and it seems to stand still for a few days before it takes its downward course4 ,the summer solstice is halfway between the two points of the equinox4 ,cancer1 the ,crab4--,this is a small constellation of dull stars that is chiefly interesting because it once contained the point of the summer solstice1 but that was ages ago4 ,the only thing about ,cancer to attract attention is a hazy patch of light called the ,manger4 ,on each side of the ,manger is a fairly bright star and this pair of stars is called the ,ass's ,colts2 they will help you to find ,cancer4 ,illustration ,the ,manger has often been mistaken for a comet by those who lit upon it with the naked eye1 but it is really a cluster of small stars4 ,leo1 the ,lion4--,there are two separate groups of stars that make up this king of beasts4 ,the first group takes the shape of a sickle and the other the form of a square4 ,the sickle1 which is formed of six bright stars1 is ,leo's head and shoulders1 and the four stars of the square make up his hindquarters4 ,two lines1 drawn from the ,big ,dipper across the sky1 as shown in ,fig4 #agf1 will meet the sickle and the square4 ,illustration ,the very bright star in the end of the handle of the sickle is ,regulus1 which means little king1 and far to the other side of the constellation right in the end of the ,lion's tail is another bright star called ,denebola4 ,illustration3 ,,fig4 #agf4--;,,constellations ,,of ,,the ,,lion ,,and ,,big ,,dipper4 ,virgo1 the ,virgin4--,this constellation is of interest1 because the ,sun again crosses the point where the equator and ecliptic meet1 and the days and nights are again of the same length everywhere on the ,earth1 just as they were at the spring1 or vernal equinox4 ,but this time1 when the ,sun is in ,virgo1 it crosses the equator from north to south about ,september #ba and so this equinox is called the autumnal equinox1 which means equal autumn days4 ,illustration ,by drawing a line from ,polaris through ,mizarin through the handle of the ,big ,dipper and producing it beyond ,arcturus1 and on until it reaches a big1 bright1 white star you will have reached ,virgo1 as shown in ,fig4 #agg4 ,this big1 white1 bright star is ,spica1 and it is the chief star in ,virgo4 ,the ancients always represented ,virgo1 the ,virgin1 with a sheaf of wheat in one hand and a sickle in the other4 ,the ,virgin and the harvest always went together in the minds of the ancients and this accounts for the pictures of ,virgo in the almanacs of the present time4 ,libra1 the ,balance4--,a small constellation named for the ancient ,roman pound weight4 ,illustration ,the constellation of ,libra is not nearly as old as the others in the zodiac1 in fact it is thought that there were only eleven constellations in the zodiac when they were first mapped out thousands of years ago1 although there were twelve signs or spaces in the zodiac4 ,its position is shown in ,fig4 #agh4 ,then in the days of the ,roman ,empire1 about #cjj years before ,christ1 some genius clipped the claws of the ,scorpion and made its stars into a pair of scales4 ,this was a very clever idea1 for the autumnal equinox then took place in this sign of the zodiac1 and the stars in this sign were given the name of ,libra1 as the equal days and nights called to mind the balance4 ,illustration3 ,,fig4 #agg4--;,,constellations ,,of ,,virgo ,,the ,,virgin4 ,illustration3 ,,fig4 #agh4--,,libra1 ,,lion1 ,,scorpio1 ,,virgo4 ,scorpius1 the ,scorpion4--,a summer constellation4 ,if ,libra takes up only a small part of one sign of the zodiac ,scorpius makes up for it by nearly covering two signs4 ,to the old astrologers1 ,scorpius was the 8power of darkness0 and the 8accursed constellation10 and when they cast their horoscopes they attributed to it 8woe and discord1 war and disease40 ,illustration ,the constellation of ,scorpius is one of the very few which really looks its part4 ,in the end of its curved tail there are two stars which are ready to sting if he ever strikes1 but he has never struck yet4 ,the heart of the ,scorpion is a big1 bright red star called ,antares1 which means the rival of ,mars1 and when ,mars is in the constellation of ,scorpius it is hard to tell them apart4 ,antares will prove useful in finding the ,scorpion as there are no other bright stars in that part of the sky4 ,the position of ,scorpius is shown in ,fig4 #agh4 ,sagittarius1 the ,archer4--,a summer constellation3 ,it is made up of many stars which can be seen with the naked eye and is always pictured in the almanacs as a centaur1 or man-horse1 shooting an arrow from a bow at the heart of the ,scorpion4 ,illustration ,sagittarius is a fine constellation1 right in the path of the ,milky ,way1 and this makes it easy to find4 ,there are several interesting things in this constellation and among them are the clusters of stars and nebul4 ,then there are seven stars in ,sagittarius1 which make a little dipper turned upside down1 and because it is in the ,milky ,way it is called the milk dipper2 when you once find it1 you will never be able to see ,sagittarius again without seeing the milk dipper4 ,illustration3 ,,fig4 #agi4--,,lyra1 ,,aquila1 ,,capricornus4 ,the winter solstice1 that is1 the most southern point which the ,sun reaches1 lies halfway between the constellations of ,scorpius and ,sagittarius and also between the two stream lines of the ,milky ,way4 ,when the ,sun reaches this point1 which is the #bjth of ,december1 the noonday shadows are the longest and the ,sun seems to again stand still until ,christmas1 when he will begin to move north once more4 ,capricornus1 the ,sea-,goat4--,a constellation of autumn3 ,on the same plan that the ancients made ,sagittarius a man-horse1 so they made ,capricornus a goat-fish4 ,though ,capricornus is a small and poor constellation when viewed with the naked eye1 the early astrologers thought more of him than all the other constellations of the zodiac put together4 ,while the stars of ,capricornus do not look anything like a sea-goat1 he can be easily found by drawing a line from ,vega in ,lyra to ,altair in ,aquila and producing it until you come to the zodiac as shown in ,fig4 #agi4 ,illustration ,the two brightest stars of ,capricornus are in his head4 ,one of these stars is a naked eye double1 but to many people it will seem merely a single star4 ,as a matter of fact it is a fine sight test1 for it takes a pair of mighty good eyes to separate them4 ,another bright star of the sea-goat is in his fishlike tail4 ,we have journeyed clear around the great circle which the ,sun travels every year1 and we are back again to ,aquarius1 the constellation we started from1 having covered all the constellations of the zodiac4 ,the ,signs of the ,zodiac4--,where the signs of the zodiac are used in almanacs they do not mean the constellations of the same name at all1 but the spaces or parts of the great circle which form the zodiac4 ,two thousand years ago the constellations and the signs of the same name were in the same spaces or parts of the zodiac1 but the signs1 by precession1 have shifted over one space to the west since that time1 while the constellations have of course remained unchanged1 and this has made a good deal of confusion4 ,it's a pretty skillet of fish1 this mixing of the signs and constellations of the zodiac1 but you will get used to it just as easily as you get used to carrying water when in camp or washing dishes4 ,how to ,read the ,almanac4--,if you were asked to find the date of any day of any month of the year you would simply look at a calendar and find it in a jiffy4 ,now1 long before calendars came into general use the almanac was freely consulted1 not only for learning days and dates1 but for much more useful information1 such as finding the dates of eclipses1 the beginning of seasons1 the rising and setting of the ,sun1 ,moon and planets and the conjunctions and oppositions of these bodies1 planting potatoes and the year the father of your country was born4 ,to read an almanac easily you should learn the following signs3 ,the ,sun ,mercury ,full ,moon ,venus ,last ,quarter ,the ,earth ,new ,moon ,mars ,first ,quarter ,jupiter ,conjunction ,saturn ,opposition ,uranus ,neptune ,conjunction4--,when this sign is used it means that two planets1 or the ,sun and a planet1 or the ,moon and a planet1 are on the same side of the ,earth4 ,opposition4--,when this sign is used it means that two planets1 or the ,sun and a planet1 or the ,moon and a planet1 are on opposite sides of the ,earth4 ,to see how these signs work out suppose you look up the month of ,january1 #aiae1 in an almanac4 ,the first line1 besides showing that it is the first day of the year1 the first day of the month and that it is ,friday1 also shows that the 7,moon7 is full4 ,it further gives the time the 7,sun7 rises and sets1 the length of the days in hours and minutes1 the 7,moon's7 age in days1 and when it rises and sets4 ,then on the same line the following signs are given3 and this means that a conjunction of ,mercury and ,mars will take place on this date2 that is1 that they will be nearer to each other from our line of sight than at any other time for a long while4 ,on the next line1 which is the #bnd of ,january1 the following signs are given3 greatest brilliancy2 in perihelion 2 the first of which means that ,venus has reached its greatest brightness2 the second1 that the ,earth is the nearest to the ,sun that it will get1 and the third1 that there is a conjunction of ,neptune and the ,moon2 and so on for every day of the year4 ,note3 ,a good almanac for daily star information is the ,old ,farmers' ,almanac1 a copy of which you can get by sending #aa cents to ,william ,ware and ,company1 ,boston1 ,mass4 ,,chapter ,,xii ,,valuable ,,information ,photographing the ,stars4--,there are some interesting things you can do with an ordinary camera in the way of photographing the stars4 ,a camera is made up of three principal parts1 and these are 7#a7 a convex lens1 which forms the image of the object to be photographed2 7#b7 a light-tight box1 which keeps out all the light except that which passes through the lens1 and 7#c7 a plate1 or film holder1 which holds the sensitive plate1 or film1 in the camera and keeps it perfectly dark until you are ready to have the image formed on it4 ,the instant the lens is allowed to form an image on the sensitive plate1 or film1 we get out of the optics of photography and into the chemistry of it4 ,the sensitive plate1 or film1 is coated with a thin layer of salts of silver and bromide1 heated with gelatine and a little water1 and when these substances are thoroughly mixed1 an emulsion results1 and this is spread on glass plates or on celluloid films4 ,when the plate is exposed1 that is1 when the image has been formed on it1 it is developed4 ,the developing is done by placing the plate in a solution of pyrogallic acid1 or hydroquinone and water4 ,the plate1 or film1 is now put in the fixing bath1 which is simply a solution of hyposulphite of soda and water4 ,this fixing bath prevents any further action of the light on the plate1 or film4 ,but the picture on the glass plate1 or celluloid film1 looks all same like a ,chinese chromo1 for the light and dark parts are just the reverse of that of the object which was photographed2 in other words1 where the picture should be white1 it is black1 and where it should be black1 it is white1 and this is the reason it is called a negative4 ,illustration3 ,,fig4 #ahj4--;,,camera ,,pointing ,,to ,,north ,,star4 ,to get a picture of the object1 as it looks to the eye1 a sheet of paper1 also coated with salts of silver1 is laid flat on the negative and held close to it in a printing frame when it is exposed to the light of the ,sun4 ,when the paper is printed dark enough by the ,sun1 it is toned to give it a pleasing color and fixed to make it last a long time1 and when washed and dried the image of the object1 true to life1 is there1 a wonderful record for all time1 nearly4 ,this then1 briefly1 is how the ,sun1 or other source of light1 makes an image1 how the image is fixed on a dry plate1 or film1 and how a picture is printed from the negative1 and having found out this much let's see how we can make it do a little star work for us4 ,there is not much we can do in the way of making pictures of the things in the sky with a small camera1 but the few things we can do are mighty interesting1 and show the stars in a way you can never see them with the naked eye4 ,to make star trails is one of these interesting things4 ,first1 set your camera on a tripod1 or other firm support1 and focus it on a tree or something as far off as you can see it in the daytime4 ,now1 on a dark night1 when there is no ,moon1 set your camera so that the lens is pointing directly at the ,north ,star1 as shown in ,fig4 #ahj4 ,set the shutter of your camera for a time exposure and open it4 ,illustration3 ,,fig4 #aha4 ,,star ,,trails4 ,you can go to bed now and let the stars work for you while you sleep1 that is if you can get up before daylight the next morning1 but if you cannot do this stay up as long as you can1 three or four hours1 anyway1 before you close the shutter4 ,now1 when you develop the plate1 or film1 and make a print from it you will have a record of the apparent path of the stars1 as shown in ,fig4 #aha1 but which is1 of course1 due to the ,earth turning round on its axis4 ,if you set your camera with the lens pointing toward the ecliptic1 that is1 the path of the ,sun1 the star trails will be long1 straight lines1 and this will make another interesting record4 ,by pointing your camera toward that part of the sky and during that time of the year when there are showers of meteors1 and opening the shutter of your lens1 you stand a chance1 though it is not a very fat one1 of catching one of these wily shooting stars on your plate1 and if you do succeed--well1 you will have a picture that is a curiosity4 ,you can photograph the ,sun with an ordinary camera and make his disk as large as you want to1 but you will get nothing more on your plate than a white spot4 ,the ,moon can likewise be photographed1 but if you focus it sharp on the plate it will not be much larger than a mere point of light1 and if you get a disk large enough to see there will only be a small white spot on your finished print4 ,to make good photographs of the ,sun1 ,moon and planets1 a big telescope driven by clockwork to offset the turning of the ,earth is needed4 ,such a telescope is called an equatorial telescope1 and when it is set so that an object in the sky is in the field of view1 it will remain right there as long as you want it1 and when you make a photograph of the object it will be as sharp and as clear as though both it and the ,earth were standing perfectly still4 ,if you think enough of the stars to try to photograph them with your little camera1 ,i should say there is a very good chance of your being able to photograph them sometime through an equatorial telescope for all things come to the boy who wants them hard enough4 ,what the ,stars ,are ,made of4--,to know what the stars are made of is to know more about them than men knew of the ,earth a few hundred years ago4 ,but just think of looking at a star like ,aldebaran1 which is so far away that it takes #de years for its light to reach the ,earth--light travels eleven million miles a minute--and then saying it is made of iron1 and mercury and hydrogen and sodium and half a dozen other substances6 ,now you ask1 8,how is it done80 ,and ,i'll say with a glass prism1 and then we'll have made a flying start4 ,now a glass prism is a three-sided piece of glass--the ends don't count--as shown in ,fig4 #add1 and it is just as wonderful in its way as a lens is wonderful in its way4 ,if you will hold a prism to your eye and look at the flame of a candle through it1 you will see the flame in all the brilliant colors of the rainbow1 and these bright colors form what is called a spectrum4 ,now make another experiment2 cover a window1 on which the ,sun shines1 with a sheet of cardboard1 in the middle of which you have cut a horizontal slit with a sharp knife1 about #a inch long and _/ inch wide4 ,make the room perfectly dark except for the light which comes in through the slit in the cardboard1 and set a prism in front of the slit1 as shown in ,fig4 #ade4 ,the beam of sunlight which passes through the prism will be split up1 or decomposed1 as it is called1 into the seven colors of the rainbow1 but the colors will be much brighter4 ,if you will fix another sheet of white cardboard in a vertical position so that the colors will shine on it in a band1 the colors1 beginning with red at the bottom1 next orange1 then yellow1 green1 blue1 indigo and violet1 will follow each other to the top bright and beautiful4 ,these rainbow colors1 spread out in a band on the screen1 form what is called the solar spectrum1 that is1 the spectrum which is produced by sunlight4 ,this beautifully colored spectrum is really made up of a great many images of the slit in the cardboard1 one for each wave-length of the light4 ,if the slit is made very narrow1 the images of the slit will not overlap much and you can tell whether any of the wave-lengths are missing by looking for fine black lines crossing the spectrum4 ,such dark lines are very important in finding out what the ,sun and ,stars are made of4 ,illustration3 ,,fig4 #ahb4--;,,boy ,,looking ,,through ,,prism ,,at ,,slit ,,in ,,cardboard4 ,all you have to do is to stand away from the slit five or six feet and look at the beam of light through a prism just as you did at the flame of the candle4 ,this is the simplest form of a spectroscope1 that is an instrument for splitting up the light of any object which is self-luminous1 into a spectrum1 as shown in ,fig4 #ahb4 ,when you look at the sunlight streaming in through the slit in the cardboard you will see a number of dark lines crossing the colored band4 ,these dark lines are called ,fraunhofer's lines1 because ,fraunhofer1 who was a ,german telescope maker1 was the first to show how important they are4 ,the chief dark lines of the ,sun's spectrum are known by the letters of the alphabet1 and1 like the colored images of the slit1 they are always in the same place4 ,they are shown in ,fig4 #ahc4 ,having found out a little about the spectrum and how it is formed by the ,sun1 let's find out next how it tells us what the ,sun and the stars are made of4 ,illustration3 ,,fig4 #ahc4--;,,fraunhofer',s ,,lines4 ,now1 in the ,sun's spectrum there are a pair of lines close together and near the middle which are called the ,d lines--see ,fig4 #ahc--;and when a beam of sunlight is split up by a spectroscope1 or rather by the prism of a spectroscope1 these ,d lines always appear in the yellow part of the spectrum4 ,there was a time1 and not so very long ago1 when no one had the faintest idea why the ,sun's light did not contain these two wave-lengths1 when the spectrum from a candle flame was a continuous band of light without dark lines4 ,then two experimenters1 ,kirchhoff and ,bunsen1 found that various substances when converted into luminous gases in a hot flame always produced spectra which consisted only of certain bright lines4 ,thus it was found that sodium gas gives two bright lines in the exact positions of the ,d lines of the ,sun's spectrum4 ,this made it look as if the ,sun contained no sodium4 ,but the experimenters did something else3 they placed a very brilliant light back of the sodium gas and on looking through their spectroscope they saw a continuous spectrum with black ,d lines4 ,this meant that the sodium gas had absorbed from the light passing through it the wave-lengths which it had given out when shining by itself4 ,we now know that the ,sun is surrounded by a layer of gases which is somewhat cooler than the interior of the ,sun and that each substance in this 8reversing layer10 as it is called1 takes out some of the light which is characteristic of it and thus produces the ,fraunhofer lines4 ,in the same way iron and other metals and sodium and other substances which are heated until they become gases1 and hydrogen and other gases which are aflame1 produce spectra consisting of certain bright lines1 and as the light from the ,sun also produces black lines in the same identical places1 it is known that the ,sun contains these different substances which are heated up in it to a white heat4 ,illustration3 ,,fig4 #ahd4--,,the ,,spectroscope4 ,it's the same thing with the stars4 ,it makes no difference if the light is made by burning some substance a few inches away from the slit of the spectroscope1 or whether it has traveled #ij millions of miles from the ,sun--which takes about #h minutes1 or #de years for the light to reach it from ,aldebaran1 it always acts exactly in the same way2 and so we know a good deal about the stuff the stars are made of4 ,let's see now1 how a real spectroscope is made1 for it isn't always convenient to have a pitch dark room1 nor is it a very exact way to hold the prism to your eye when examining the light of burning sodium1 or hydrogen gas1 or other substances4 ,the spectroscope is an instrument made so that the light of a substance burned at one end will pass through a prism and will form a spectrum on the retina of the eye at the other end4 ,it is usually made up of two tubes mounted on a stand at an angle with the prism between them1 as shown in ,fig4 #ahd4 ,in the end of the first tube1 which is called a collimator1 a very narrow slit is cut1 and it is at this end that the substance is placed which is to be burned and whose light is to be split up and examined4 ,a convex lens is fitted in the other end of the collimator1 or first tube1 so that the light after passing through the slit will then pass in a beam through the prism4 ,the other tube--the one you look through--is called a telescope and in this one is fitted a convex object glass and an eyepiece which magnifies the spectrum made by the prism4 ,when a camera is used to photograph the spectrum the eyepiece is taken out of the tube of the spectroscope and a little camera is put in its place4 ,in this way the camera and the spectroscope are combined and this helps chemists to compare the spectra of different burning substances far better than they could do with the naked eye alone4 ,to photograph the spectrum of the ,sun the eyepiece of the big telescope is taken out and the end of the tube of the spectroscope with the slit in it is fitted in its place4 ,in making a photograph of the spectrum of a star the slit is not needed1 for the light of the star itself is but a mere point4 ,in photographing the spectrum of the ,sun and stars three wonderful instruments are combined1 namely1 the telescope1 the spectroscope and the camera2 perhaps ,i should have said four wonderful instruments1 for without the brain of a genius using them the ,sun and stars never would have given up their secrets4 ,,appendices ,,appendix ,a ,according to the official ,handbook of the ,boy ,scouts1 if you are a ,scout and want to win a merit badge for starcraft1 you must 7#a7 ,have a general knowledge of the nature of the stars and planets4 7a7 ,by the nature of the stars and planets is meant their colors and what they are made of4 ,their sizes and their distances from the ,earth in a general way may also be included4 7b7 ,it is easy to tell the color of both the stars and the planets by looking at them1 or by looking them up in the foregoing chapters4 7c7 ,the spectroscope shows that the stars are made of metals and gases and other substances which we have on ,earth4 ,the planets are probably made of the same kinds of metals1 gases and substances as those which form the ,earth1 but there is no way of proving this1 for the planets shine by reflected light1 and in this case the spectroscope is of little use4 7d7 ,the stars are known to be suns as large or larger than our ,sun2 while the planets are about as large as our ,earth--some smaller and some larger4 7e7 ,all of the planets are within #b1hjj millions of miles of the ,earth1 while the nearest star1 except our ,sun1 is #be trillions of miles from the ,earth1 or #h1jjj times as far away4 7#b7 ,have a general knowledge of the movements of the stars and planets4 7a7 ,while all the stars revolve in orbits and are moving through space at high speed1 they are so far away from us that they seem to be fixed and for all practical purposes they may be considered to be fixed in their positions4 7b7 ,all the planets turn on their own axes and travel in orbits round the ,sun4 7#c7 ,point out and name #ab principal constellations4 7a7 ,twelve easy constellations are3 7#a7 ,the ,big ,dipper2 7#b7 ,the ,little ,dipper2 7#c7 ,cassiopeia2 7#d7 ,pegasus2 7#e7 ,orion2 7#f7 ,auriga and 7#g7 ,taurus1 all of which are shown in ,chapters ,i and ,,ii2 7#h7 ,gemini2 7#i7 ,leo2 7#aj7 ,virgo2 7#aa7 ,the ,scorpion1 and 7#ab7 ,sagittarius1 which are constellations of the zodiac1 and are shown in ,chapter ,,xi4 7#d7 ,find the ,north by means of other stars than the ,pole ,star 7which is the ,north ,star7 in case that star is obscured by clouds4 7a7 ,this can be done by finding the constellation of ,cassiopeia1 see ,chapter ,i2 and also by ,pegasus2 ,auriga and ,orion1 as explained in ,chapter ,,ii4 7#e7 ,have a general knowledge of the positions and movements of the ,earth1 ,sun1 ,moon1 and the ,planets2 and of tides1 eclipses1 meteors and comets4 7a7 ,by reading the chapters on the ,sun1 ,planets1 ,earth and ,moon and 7b7 ,other things in the sky carefully1 you will be able to pass the requirements named in ,no4 #e4 7#f7 ,plot on at least two nights per month for six months the positions of all naked eye planets visible between sundown and one hour thereafter4 ,the plot of each planet shall contain at least three fixed stars with their names or designations2 colors of planets and stars are to be recorded as observed4 7a7 ,how to plot the position of a planet is fully explained in the chapter on ,planets1 but you should also read the one on ,the ,stars of the ,zodiac1 and have a good star map 7,app4 ,o74 ,,appendix ,b4 ,figures4--,when explaining the positions and forms of things1 it is often necessary to use certain terms and figures1 that is to say1 lines which are either real or imaginary1 but which can be drawn on paper4 ,see ,fig4 #ahe4 7#a7 ,a straight line is1 of course1 a line which runs uniformly in the same direction1 and which is regular and without curves4 ,a straight line is the shortest distance between two points4 7#b7 ,when we say that lines are parallel1 we mean that they lie so that every part of each is equally spaced from the other4 7#c7 ,a line is horizontal when it is parallel with the level surface of the ,earth under it4 7#d7 ,a line is perpendicular to the surface of the ,earth when it is plumb1 that is1 in a line with the center of the ,earth4 7#e7 ,a vertical line generally means a plumb line4 7#f7 ,a right angle is formed when a vertical1 or a perpendicular1 line meets a horizontal line4 7#g7 ,a circle is a curved line1 all points of which are equally distant from its center4 ,circular means round like a circle4 7#h7 ,by diameter is meant a straight line drawn from one side1 or half of a circle1 to the opposite side through its center4 7#i7 ,the radius of a circle is a straight line drawn from the center of a circle1 or a ball1 to its circumference4 7#aj7 ,a ring is a disk or object having a circular hole cut in its center4 7#aa7 ,an arc of a circle is a part of a circle4 7#ab7 ,a quarter circle is1 of course1 the one-fourth part of a circle4 7#ac7 ,a tangent is a line which touches a curve but does not cut it4 7#ad7 ,an ellipse is an oval figure1 drawn on a plane surface4 7#ae7 ,the equator is a circle which divides the ,earth or other ball into equal parts1 and is #ij degrees from the north and south poles4 7#af7 ,the ecliptic is a circle round the ,sky in whose plane lies the orbit of the ,earth4 ,illustration3 ,,fig4 #ahe4--;,,geometrical ,,figures4 ,,appendix ,c ,,the ,,greek ,,alphabet ,many of the brighter stars have names1 as ,aldebaran1 ,capella1 ,sirius1 etc41 but astronomers now indicate the stars of a constellation by the letters of the ,greek alphabet4 ,the usual method is to call the brightest star of a constellation 1 that is1 ,alpha1 the next brightest which is ,beta1 and so on1 but sometimes the stars are lettered in order of position in the sky4 ,the following is the ,greek alphabet3 ,alpha ,nu ,beta ,xi 7,zi7 ,gamma ,omicron ,delta ,pi ,epsilon ,rho ,zeta ,sigma ,eta ,tau ,theta ,upsilon ,iota ,phi ,kappa ,chi ,lambda ,psi ,mu ,omega ,,appendix ,d ,,star ,,tests ,,for ,,eyesight ,there are a number of stars which are considered to be good tests for the seeing power of the eyes4 ,the faint stars of the ,pleiades are a fine test of this kind2 but usually these tests are double stars and while one will be bright and easily seen its companion will be very faint4 ,the test is to see the faint one1 and if you can see it you may consider you have very good eyesight4 ,eyesight tests are given on the following pages3 ,page #aa--,mizar and ,alcor #cd--,spots on the ,sun #id--;,grimaldi on the ,moon #aai--,nebula in ,orion #aej--;,epsilon in ,lyra #aej--,pleiades #ahb--;,alpha and ,beta in ,capricornus ,,appendix ,e ,,magnitudes ,,of ,,stars ,there are not nearly as many stars in the sky as you might at first suppose4 ,the stars are divided into magnitudes1 that is1 according to their brightness4 ,stars of the first magnitude are the brightest stars2 stars of the second magnitude are second brightest1 and so on4 ,the total number of stars which can be seen with the naked eye on any one night in the ,united ,states is probably not more than #c1jjj4 ,the following table gives the number of stars of the different magnitudes up to and including the sixth3 ,magnitudes ,number of ,stars #ast #bj #bnd about #fe #crd about #bjj #dth about #ejj #eth about #a1djj #fth about #e1jjj ,,appendix ,f ,,first ,,magnitude ,,stars ,the brightness of a star is known by its magnitude4 ,a star of the first magnitude is one of the #bj brightest stars1 and is #b times as bright as a star of the second magnitude2 a star of the second magnitude is #b times as bright as a star of the third magnitude2 and so on4 ,a star of the sixth magnitude can just be seen with the naked eye on a clear night when there is no ,moon4 ,fifteen of the twenty first magnitude stars can be seen in our latitude1 and these are3 ,,of ,,of ,,star ,,constellation #a4 ,sirius1 the ,dog ,star1 in ,canis ,major #b4 ,capella 8 ,auriga #c4 ,arcturus 8 ,bootes #d4 ,vega 8 ,lyra #e4 ,rigel 77 8 ,orion #f4 ,procyon 8 ,canis ,minor #g4 ,betelgeux 77 8 ,orion #h4 ,altair 8 ,aquila #i4 ,aldebaran 8 ,taurus #aj4 ,spica 8 ,virgo #aa4 ,antares 8 ,scorpius #ab4 ,pollux 8 ,gemini #ac4 ,regulus 8 ,leo #ad4 ,deneb 8 ,cygnus #ae4 ,fomalhaut 8 ,piscis ,australis ,,appendix ,g ,,constellations ,,having ,,first ,,magnitude ,,stars ,the following important constellations are not described in the foregoing chapters of this book4 ,they can be found1 though1 without trouble1 since a star of the first magnitude is located in each4 ,canis ,major1 the ,big ,dog1 is a winter constellation1 and can be seen on your meridian at #i o'clock ,p4 ,m4 in ,february4 ,look for it in the southern sky and you will quickly find it because of the dazzling brightness of ,sirius1 the ,dog ,star4 ,bootes 7pronounced ,bo--tes71 the ,bear ,leader1 is a summer constellation1 and can be seen on the meridian at #i o'clock ,p4 ,m4 in ,june4 ,it is to the north of the ecliptic1 or path of the ,sun4 ,it lies between a crown of stars and ,virgo4 ,you can't miss it1 for midway is ,arcturus1 a red star of the first magnitude4 ,lyra1 the ,lyre4--,is a summer constellation1 and can be seen on the meridian at #i o'clock ,p4 ,m4 in ,august4 ,look for it almost overhead1 and you can't mistake it1 for three bright stars1 of which ,vega is one1 form a triangle4 ,canis ,minor4--,the ,little ,dog3 is a spring constellation1 and can be seen on the meridian at #i o'clock ,p4 ,m4 in ,march4 ,it lies to the south of the constellation of ,gemini1 the ,twins1 and ,cancer1 the ,crab4 ,in it you will see ,procyon1 the ,little ,dog ,star4 ,aquila1 the ,eagle4--,is a summer constellation1 and can be seen on the meridian in ,august4 ,look for it south of ,lyra1 and far to the west of ,pegasus4 ,the star that put ,aquila on the map is ,altair4 ,cygnus1 the ,swan4--,is also a summer constellation1 and can be seen on your meridian at #i o'clock ,p4 ,m4 in ,september4 ,you will find it north of ,pegasus and east of ,lyra1 and in it you will see the ,northern ,cross clearly traced out with seven stars1 the brightest one being ,deneb1 a first magnitude star4 ,piscis ,australis1 the ,southern ,fish1 is an inconspicuous constellation far south of the ,equator4 ,fomalhaut1 its brightest star comes only #bj degrees above our horizon and must be looked for when it is near the meridian--about #i o'clock ,p4 ,m4 in ,october4 ,,appendix ,h ,,colored ,,stars ,you can easily notice that the stars differ in color4 ,the following list gives the colors of a few of the brighter stars3 ,,white ,,stars3 ,sirius1 ,regulus1 ,vega4 ,,blue ,,stars3 ,rigel and ,spica4 ,,red ,,stars3 ,aldebaran1 ,antares1 and ,betelgeux4 ,,green ,,stars3 ,b ,librae4 ,,yellow ,,stars3 ,the ,sun1 ,arcturus1 and ,capella4 ,,appendix ,i ,,double ,,stars ,when two stars are very close together they form what is called a double star1 but double stars of which the two components are really near together in space and revolve around each other usually cannot be resolved1 that is separated1 into two stars without the aid of a telescope4 ,the ,north ,star2 ,rigel1 ,castor2 ,procyon and ,sirius1 are all famous double stars4 ,,appendix ,j ,,variable ,,stars ,a variable star is one whose brightness changes from time to time4 ,a great many variable stars are known1 but very few of them can be seen with the naked eye4 ,there are different reasons given for a star varying in brightness4 ,our ,sun is a variable star1 and we are told that this is due to his spots4 ,another type of variation is perhaps produced by pulsations--the star periodically expanding and contracting4 ,again a double star formed of two bright stars which revolve round each other1 as many double stars do1 may eclipse one another1 and this would cause a change in brightness4 ,here1 then1 are three good reasons for a star being variable4 ,the following are a few of the variables which can be seen with the naked eye3 ,betelgeux1 in ,orion4 ,alpha ,cassiopeia1 that is1 the brightest star in ,cassiopeia4 ,beta ,lyra1 that is1 the second brightest star in ,lyra1 and ,beta ,pegasus1 that is1 the second brightest star in ,pegasus4 ,mira1 in ,cetus4 ,algol1 in ,perseus4 ,,appendix ,k ,,invisible ,,or ,,dark ,,stars ,stars are born1 live and die1 just like human beings4 ,all the stars1 including the ,sun1 are either in the process of making1 are at their brightest brilliancy1 are dying out1 or are cold and dead or have not yet become bright4 ,procyon and ,sirius is each attended by a comparatively dark companion4 ,procyon and ,sirius both move slowly back and forth a short distance in the sky and this motion was attributed to the pull of satellites long before these bodies were discovered with the telescope4 ,,appendix ,l ,,the ,,equation ,,of ,,time ,,table ,,of ,,the ,,equation ,,of ,,time ---------------------------------------- --------------------- ,day of ,january ,february ,march ,april ,may ,june ,month ---------------------------------------- --------------------- m s m s m s m s m s m s #a ,s #c #ca ,s #ac #dd ,s #ab #cg ,s #d #f ,f #b #ef ,f #b #cj #f ,s #e #di ,s #ad #ae ,s #aa #cc ,s #b #cg ,f #c #bg ,f #a #da #aa ,s #g #ei ,s #ad #bg ,s #aj #ai ,s #a #ad ,f #c #de ,f #j #dd #af ,s #i #di ,s #ad #ai ,s #h #eg ,f #j #d ,f #c #dh ,s #j #ah #ba ,s #aa #bd ,s #ac #eb ,s #g #bh ,f #a #ab ,f #c #ch ,s #a #bc #bf ,s #ab #ci ,s #ac #aj ,s #e #ef ,f #b #aj ,f #c #ae ,s #b #bg #ca ,s #ac #ce ,s #ab #ac ,s #d #bd ,f #b #ef ,f #b #ci ,s #c #ch ---------------------------------------- --------------------- ---------------------------------------- ---------------------- ,day of ,july ,august ,september ,october ,november ,december ,month ---------------------------------------- ---------------------- m s m s m s m s m s m s #a ,s #c #bh ,s #f #aj ,s #j #f ,f #aj #h ,f #af #ah ,f #aa #c #f ,s #d #bd ,s #e #df ,f #a #ca ,f #aa #da ,f #af #ag ,f #i #c #aa ,s #e #aa ,s #e #h ,f #c #ac ,f #ac #d ,f #ae #ef ,f #f #ea #af ,s #e #df ,s #d #ae ,f #d #eh ,f #ad #af ,f #ae #ac ,f #d #cj #ba ,s #f #i ,s #c #i ,f #f #de ,f #ae #ac ,f #ad #aj ,f #b #b #bf ,s #f #aa ,s #a #ea ,f #h #bi ,f #ae #ed ,f #ab #de ,s #j #bh #ca ,s #f #ab ,s #j #bd ,f #aj #h ,f #af #af ,f #aa #c ,s #b #ee ---------------------------------------- ---------------------- ,as we have seen in ,chapter ,x every day of the year is exactly #bd hours long by our clock time4 ,the time by the ,sun is usually either ahead or behind local clock time4 ,the difference between clock time and ,sun time is called the equation of time1 and a table to show how many minutes and seconds the ,sun is fast or slow1 according to clock time1 is given above1 taken from 8,the ,new ,astronomy10 by ,professor ,todd1 who has kindly permitted me to use it here4 ,in the table ,s means that the ,sun is slow1 that is1 that the ,sun does not cross the meridian until after the clock shows noon1 and ,f means that the ,sun is fast1 that is1 that the ,sun has crossed the meridian before the clock shows noon4 m means minutes1 and s means seconds above the figures4 ,the table gives the average values of the equation of time1 which may differ by a few seconds from the values for any particular year4 ,,appendix ,m ,,the ,,kullmer ,,star ,,finder ,the star finder shown in the picture was invented by ,dr4 ,c4 ,j4 ,kullmer1 of ,syracuse1 ,n4 ,y41 and has been highly praised by many great astronomers4 ,illustration3 ,,fig4 #ahf4--,,kullmer ,,star ,,finder4 ,you should own one if possible1 for you do not need to know anything about the stars to operate it4 ,it is mounted on the principle of a big telescope1 but it is a naked eye instrument1 an arrow taking the place of the telescope4 ,the finder is placed on a table1 or other level surface1 with the dial facing north4 ,then the pointer and dial are set for the day and hour when you want to find the position in the sky of a certain constellation4 ,the indicator is turned to the name of the constellation on the dial1 and this also tells the direction to set the arrow4 ,this is all there is to it and the arrow points right at the group of stars you want1 whether they are above the horizon or not4 ,the finder can be used for many purposes1 and it is a wonderful aid in making out in the sky the path of the stars1 ,sun1 ,moon and planets1 and when they rise and set4 ,in fact1 it is a complete observatory on a small scale4 ,its cost is only #e4jj4 ,,appendix ,n ,,the ,,ellis ,,seasonal ,,twilight ,,chart ,a useful chart1 designed by ,miss ,e4 ,rebecca ,ellis1 of ,wellesley ,college1 ,wellesley1 ,mass4 ,it makes clear the changes in the lengths of the day1 the phenomena of the seasons1 etc4 ,its price is #a4jj4 ,,appendix ,o ,,the ,,camp ,,fire ,,sky ,,map ,this map1 prepared by ,prof4 ,r4 ,s4 ,dugan of ,princeton ,university1 shows the constellations as far south as the ,southern ,cross and is adjustable for the time of night1 date1 and for the latitude4 ,full instructions are given for its use4 ,it is used in many schools and colleges4 ,it is sold by the ,camp ,fire ,stores ,co41 price #ai cents4 ,,definitions ,,of ,,some ,,words ,,and ,,terms ,,used ,,in ,,this ,,book ,action4 ,the way in which a thing works4 ,affect4 ,to act upon2 to change2 to be moved or influenced by4 ,almanac4 ,a pamphlet or book containing tables showing the days of the year2 also the time the ,sun and ,moon rise and set2 the conjunctions1 eclipses and other information concerning the things in the sky4 ,the word almanac is supposed to be derived from the ,arabic article al and the verb manac1 which means to count4 ,angular measurements4 ,see ,appendix ,b4 ,aphelion4 ,the point where a planet or a comet is farthest away from the sun4 ,apparent4 ,to seem real4 ,the daily motion of the ,sun round the ,earth is only apparent1 for we know it is the ,earth which turns round on its axis instead4 ,arc4 ,see ,appendix ,b4 ,arc of circle4 ,see ,appendix ,b4 ,aspect4 7#a7 ,any curious appearance of an object1 especially if the object changes in appearance4 7#b7,the figure formed by a planet with the stars of the constellation which it is in4 ,astrologer4 ,one who forecasts the life of a person on the supposition that the stars control it4 ,astronomer4 ,one who is skilled in seeing the stars and who knows them4 ,atom4 ,a very small particle of matter4 ,see ,molecule2 ,matter4 ,attract4 ,to pull toward4 ,the attraction of the ,sun and the ,earth for each other is due to gravitation4 ,attraction4 ,a force which pulls one body to another4 ,attraction of ,gravitation4 ,a force which pulls all bodies to each other4 ,auditory nerve4 ,a nerve that carries the impressions of sound which reach the ear to the brain4 ,aurora borealis4 ,the ,northern ,lights4 ,a glowing light effect which takes place in the ,arctic ,circle4 ,it can often be seen from our ,northern ,states and sometimes from the ,southern ,states4 ,the same kind of lights appear in the ,antarctic ,circle4 ,these ,southern ,lights are called ,aurora ,australis4 ,axes4 ,plural of axis4 ,axis4 ,an imaginary line on which a body turns4 ,axis of rotation4 ,an imaginary line round which anything turns or spins4 ,axle4 ,a wood or metal rod on which one or more wheels turn1 or it may turn with the wheel or wheels4 ,badge of merit4 ,a badge awarded by the organization of ,boy ,scouts to members who can show a certain amount of skill in doing certain things4 ,see ,appendix ,a4 ,band4 7#a7 ,a flat strip of any material1 or 7#b7 such a strip whose ends are joined together4 ,beam4 ,rays of light which are parallel4 ,see ,ray4 ,bearing4 7#a7 ,a piece of metal1 or a bit of agate or other jewel1 on which a pivot1 spindle or shaft turns4 7#b7 ,a direction as found by the ,sun or stars1 or by the compass1 sextant or other means4 ,body4 ,any separate and distinct amount of matter when held together4 ,the ,sun and ,moon are heavenly bodies4 ,degree4 7#a7 ,the #cfjth part of a circle4 7#b7 ,indicated by this sign 4 ,device4 7#a7 ,an apparatus or instrument or any part thereof4 ,any arrangement for producing a given result4 ,diagram4 ,a sort of shorthand picture of an apparatus or part of an apparatus4 ,it is used to show in the simplest and clearest manner the construction of an apparatus4 ,diameter4 ,see ,appendix ,b4 ,direct line4 ,a straight line4 ,disk4 7#a7 ,a circular plane or flat surface4 ,since the ,sun1 ,moon and planets seem to be flat their surfaces are called disks4 7#b7 ,flat and circular like a coin4 ,dog days4 ,so called from the fact that ,sirius1 the ,dog ,star1 rises at the same time as the ,sun4 ,ecliptic4 ,see ,appendix ,b4 ,elastic4 7#a7 ,a body that will stretch and return to its original size4 7#b7 ,a thin piece of rubber4 ,ellipse4 ,see ,appendix ,b4 ,equator4 ,see ,appendix ,b4 ,equatorial4 ,having to do with or affected by the equator4 ,equatorial telescope4 ,a telescope so mounted that its principal axis is parallel with the axis of the earth and moved by clockwork so that it will follow a star4 ,evening ,star4 ,a planet which can be seen in the west just after the sun sets4 ,fixed4 7#a7 ,fastened securely4 7#b7 ,the stars are called fixed because they never seem to change their positions4 ,forecast4 ,a prediction of some future event4 ,a forecast may be founded on fancy or on fact4 ,a horoscope of a person is a forecast based on the fancy of an astrologer4 ,a weather forecast is founded on the action of a barometer1 and even then the forecast is uncertain enough4 ,forecasts of the time of eclipses1 the return of comets and the like are founded on cold scientific facts and hence come true at exactly the calculated time4 ,frequency4 ,how often an event occurs4 ,gas4 ,that form of matter which is like air4 ,some gases remain in the gaseous state at ordinary temperatures4 ,gases have a tendency to expand without limit4 ,see ,vapor4 ,generate4 ,to produce4 ,to set up2 as a battery generates a current2 the ,sun generates power4 ,gravitation4 ,the force which attracts all bodies near the ,earth to it and all bodies to each other4 ,heavens4 ,the sky4 ,the space as far as the eye can see about the ,earth4 ,the space in which the stars and their planetary systems move4 ,horizontal4 ,see ,fig4 #ahe4 ,horoscope4 ,a forecast of the future of a person made by an astrologer who pretends to read the future from the aspect or position of the planets and stars4 ,hyperbola4 ,see ,fig4 #abi4 ,hypothesis4 ,see ,idea4 ,idea4 ,a notion of a plan or scheme which may be more or less vague4 ,supposition4 ,a clearer conception of a plan or scheme which is based on such facts as may be thought of4 ,hypothesis4 ,a plan or scheme assumed to be true and carefully reasoned out from all the facts obtainable4 ,theory4 ,a plan or scheme which has been proved true by experiment1 examination or comparison4 ,illusion4 ,an image which deceives the eye4 ,the other senses can also be deceived by illusions4 ,impact4 ,coming together of two objects4 ,impress4 ,to form on1 or to affect1 as light waves impress a dry plate4 ,indicate4 ,to show4 ,to point out4 ,indicator4 ,that which points out or shows something4 ,limb4 ,the edge of the ,sun1 ,moon or ,planets4 ,lore4 ,learning on any subject4 ,lunar4 ,of1 or having to do with the ,moon4 ,magnetic lines of force4 ,the direction of the force of magnetism acting in and around a magnet4 ,magnetic storm4 ,the ,earth is a great magnet and sometimes when sun spots of unusual size or numbers appear1 the magnetic lines of force of the ,earth are violently affected4 ,this is called a magnetic storm4 ,mass4 7#a7 ,amount of matter4 7#b7 ,a lot of molecules or particles of matter brought and held together4 ,matter4 ,the substance of which a thing is formed4 ,a molecule of matter is made up of atoms1 and a mass is a lot of molecules held together by some attractive force4 ,mercury4 7#a7 ,the name of the planet nearest the ,sun4 7#b7 ,a silver white liquid metal4 ,molecule4 ,the smallest part of matter that can exist separately without the substance it forms being destroyed4 ,morning ,star4 ,a planet which can be seen in the east just before the ,sun rises4 ,morse code4 ,a telegraph code of dots and dashes invented by ,samuel ,f4 ,b4 ,morse4 ,the ,morse ,code is used for telegraph and heliograph signaling4 ,motion4 ,anything that changes position4 ,there are two kinds of motion 7a7 simple motion and 7b7 compound motion4 ,simple motion can be either translated or rotary1 while compound motion is both translated and rotary1 so that while a body is being translated1 or moved through space1 it is also rotating on its axis4 ,the ,sun and planets1 then1 have compound motions4 ,nature4 ,everything contained in space that has not been shaped by human hands4 ,nautical almanac4 ,the ,american ,nautical ,almanac is a book of the stars published by the ,bureau of ,navigation of the ,united ,states4 ,it is published three years in advance and is sold by the ,superintendent of ,documents1 ,washington1 ,d4 ,c41 at #cj cents per copy4 ,this is designed chiefly for the use of navigators of ships4 ,it gives the exact positions of the ,sun1 ,moon and planets and much other astronomical information4 ,it is based upon the calculations made by the ,united ,states ,naval ,observatory2 these are printed in the ,nautical ,almanac1 and on this all other almanacs are based4 ,northern lights4 ,see ,aurora ,borealis4 ,obscured4 ,hidden from sight4 ,official ,handbook of the ,boy ,scouts4 ,a book published by the organization of ,boy ,scouts and which contains the rules and regulations of that organization and the requirements they must meet in order to win merit badges4 ,offset4 ,to equal2 to balance4 ,opposition4 ,see ,appendix4 ,optic ,nerve4 ,the nerve that carries the impression of light received by the eye to the brain4 ,orbit4 ,the path followed by a body4 ,atoms have orbits as well as the stars4 ,the paths followed by planets and comets round the ,sun4 ,parabola4 ,see ,fig4 #abi4 ,parallel4 ,see ,appendix ,b4 ,particle4 ,a bit of matter4 ,a particle may be a bit of matter which can be seen or it may mean an amount so small that it cannot be seen4 ,pencil4 ,a group of rays from the same source of light4 ,see ,beam4 ,see ,ray4 ,pendulum4 ,a body suspended from a fixed point and free to swing4 ,perihelion4 ,the point where a planet or a comet is nearest the ,sun4 ,as the orbit of a planet is an ellipse and the ,sun is in one of the foci--that is near one end--a planet comes nearest to the ,sun when at this end of the ellipse2 and when the planet is at the other end of its orbit1 it is farthest away4 ,see ,aphelion4 ,period4 ,a certain interval of time which is marked by a repeated occurrence4 ,the period of the ,earth round its axis is about #bd hours4 ,its period around the ,sun is #cfe days4 ,periodic4 ,recurring regularly2 as a periodic comet4 ,perpendicular4 ,see ,appendix ,b4 ,phase4 ,one of the peculiar aspects of a heavenly body2 as the phases of the ,moon1 or the phases of ,venus4 ,pivot4 ,a pin1 spindle or shaft on which a wheel1 lever or device rotates or is rotated4 ,plane4 ,a level surface1 as a table top4 ,point4 ,a sharp end4 ,a starting place4 ,pores4 ,minute spaces which separate the molecules of a substance4 ,position4 ,the place of a thing when compared to the places of other things4 ,precede4 ,to go ahead of4 ,that which is before4 ,precession4 ,the act of going ahead or preceding4 ,when a revolving body such as a spinning top or the ,earth is acted upon by forces which tend to change the direction of its axis4 ,this change in the direction of its axis is called precessional motion4 ,the pole of the equator of the ,earth makes a complete turn round the pole of the ecliptic in a little over #be1jjj years and this change in the direction of the axis of the ,earth causes the points of the equinox1 that is the places where the ecliptic and the equator cross each other to move slowly from west to east and this is termed the precession of the equinoxes4 ,prediction4 ,to foretell2 to forecast4 ,predictions may be based on fancy or founded on fact4 ,principal4 ,the chief one2 the most important4 ,principle4 ,the cause of a result4 ,that on which a thing is based4 ,process4 7#a7 ,the way of working4 7#b7 ,the course of procedure4 ,produce4 ,in astronomy the word produce means the lengthening of a line4 ,it is a mathematical term4 ,protractor4 ,see ,fig4 #ih4 ,quarter circle4 ,see ,appendix ,b4 ,ray4 7#a7 ,a single line of light or heat4 7#b7 ,the path of light and heat4 ,relative position4 ,the position of a thing when compared with the position of something else4 ,see ,position4 ,revolution4 ,the turning of a thing completely round on its axis4 ,revolve4 7#a7 ,to turn completely round a circle4 7#b7 ,to turn on an axis1 as a top1 or the ,earth4 ,rigid4 ,firm1 that which cannot be easily moved out of its place4 ,ring4 ,see ,appendix ,b4 ,rise4 ,to come into sight above the horizon1 as the ,moon rises4 ,rotate4 ,to turn completely round on an axis like a top or the ,earth4 ,rotary4 ,turning completely round on an axis1 like a top or the ,earth4 ,roughly4 ,not exactly2 nearly enough for practical purposes4 ,schedule4 7#a7 ,a tabulated statement giving items concerning a subject4 7#b7 ,a timetable of any kind4 ,seeing4 ,to look at4 ,the word seeing in starcraft means to observe the stars4 ,good seeing is to observe the stars when the atmosphere is perfectly clear4 ,seems4 ,something which apparently is true and yet is not necessarily true4 ,sensation4 ,the action of one of the senses when excited by some change in matter4 ,light falling on the retina of the eye produces the sensation of light and color in the brain4 ,set4 ,to sink from sight below the horizon2 as the ,sun sets4 ,sight4 ,the power to see4 ,see ,sighting4 ,sighting4 ,to get the eye and two other objects1 such as a telescope and a star1 in a line1 as to sight ,jupiter with a telescope4 ,sign4 ,a mark1 figure or letter which astronomers have agreed to use to represent certain stars1 aspects of stars1 parts of the zodiac1 etc4 ,solar4 ,that which is of1 or has to do with the ,sun4 ,spring stars4 ,the stars which can be seen best during the spring months4 ,star chart4 ,a map of the positions of the stars4 ,starcraft4 ,useful knowledge of the stars4 ,skill shown in making the stars serve useful purposes4 ,star finder4 ,a device of any kind which will enable an unskilled person to find the planets or constellations4 ,star-lore4 ,learning concerning the mythology of the stars4 ,summer stars4 ,the stars which can best be seen during the summer months4 ,supposition4 ,see ,idea4 ,tangent4 ,see ,appendix ,b4 ,tangent line4 ,see ,appendix ,b4 ,telegraph code4 ,the alphabet of dots and dashes4 ,test4 ,to try out4 ,to examine1 compare or make an experiment which will give a needed proof4 ,theory4 ,see ,idea4 ,thumb tack4 ,a short1 thin1 sharp-pointed tack with a large flat head which permits it to be easily pushed into a board with the thumb4 ,it is used by draftsmen for fastening paper to drawing boards4 ,tilting4 ,leaning from a vertical or plumb line4 ,the axis of the ,earth is tilted from the perpendicular #bc degrees2 this throws its equator out of plane with that of the sun1 and the circle through the ,earth that is in plane with the ,sun is called the ecliptic4 ,transparent4 ,said of any substance through which light can pass easily4 ,anything that may be seen through4 ,twinkle4 ,to blink4 ,to flash with varying brightness4 ,the twinkling of stars is caused by the atmosphere4 ,uniform4 ,being the same all through or all along4 ,vapor4 ,a gas produced from a liquid or a solid and which returns to its original form at ordinary temperatures4 ,see ,gas4 ,vertical4 ,see ,appendix ,b4 ,vibration4 ,a to-and-fro movement1 as the vibration of a particle of matter4 ,a constant to-and-fro movement over the same line4 ,visible4 ,that which the eye can see4 ,wane4 ,to gradually grow smaller4 ,said of the ,moon4 ,wax4 ,to gradually grow larger4 ,said of the ,moon4 ,winter ,stars4 ,the stars which can best be seen during the winter months4 ,wireless ,messages4 ,messages which are sent and received by wireless telegraph stations4 ,wireless system4 ,an apparatus for sending and receiving messages by wireless telegraph4 ,your meridian4 ,the line running due north and south in the sky directly over your head4 ,a meridian of this kind is called a celestial meridian4 ,zodiacal lights4 ,a faint glowing light which may be seen above the western horizon just after twilight during the clear evenings of winter and spring4 ,it can also be seen just before daybreak during the clear mornings of summer and autumn4 ,,index ,air1 thickness of1 around ,earth1 #abe4 ,air waves1 #abe4 ,alcor1 in the ,big ,dipper1 #aa4 and ,mizar through a glass1 #aej4 ,aldebaran in ,taurus1 #bf1 #bh4 ,almanac1 #aga4 how to read1 #ahb4 ,old ,farmers'1 #ahd4 signs in1 #ahc4 use of1 for finding planets1 #fa4 ,alpha ,centauri nearest star1 #aah4 ,alphabet1 ,greek1 #aig4 ,morse1 #ci4 ,andromeda1 great nebula in1 #aai4 ,annular eclipse of the ,sun1 #aab4 ,antares in ,scorpio1 #ahj4 ,apennines on the ,moon1 #adf4 ,apparent noon1 #aed4 ,apparent solar day1 #aed4 ,apparent time1 #aeb4 ,aquarius1 the ,water ,bearer1 constellation of1 #fc4 the ,water ,man1 #agc4 ,aquila1 the ,eagle1 #bja4 ,arab test for eyesight1 #aa4 ,arc defined1 #aid4 ,arctic day and ,sun1 #hg4 ,arcturus in ,botes1 #bh4 ,aries1 the ,ram1 #fc1 #age4 ,aristarchus on the ,moon1 #adf4 ,ass's ,colts in ,cancer1 #agf4 ,asteroids1 #dg1 #ed4 ,astrologer's horoscopes1 #ahj4 ,atoms1 vibration of1 #abc4 ,auditory nerve1 #abe4 ,autumn1 #gd4 ,autumnal equinox1 #agh4 ,auriga1 ,capella in1 #bd4 ,auriga1 the ,charioteer1 #bc4 constellation of1 #bc4 of the ,greeks1 #bd4 the ,shepherd1 #bd4 ,barometer1 a simple1 #ce4 ,barometric pressure1 #ce4 ,belt of ,orion1 #ba4 ,beta ,pegasi1 #ah4 ,betelgeux in ,orion1 #bh4 ,big ,dipper1 the1 #b1 #d4 ,alcor in the1 #aa4 how to tell time by the1 #ab4 ,mizar in the1 #aa4 pointer stars of1 #aj4 position of1 in autumn1 #c4 in summer1 #aa4 in spring1 #aj4 in winter1 #i4 through a telescope1 #adi4 ,botes1 the ,bear ,leader1 #bja4 ,boxing the compass1 #gh4 ,boy ,scout1 merit badge for1 #aic4 ,boy ,scouts' ,handbook1 #aic4 ,brain of a genius1 #aib4 ,bull of ,light1 the1 #bf4 ,burning lens1 #cg4 ,camera1 how it is made1 #ahe4 ,cancer1 the ,crab1 #agf4 ,candle flame1 #cj4 ,canis ,major1 constellation of1 #bh1 #bja4 ,canis ,minor1 the ,little ,dog1 #bja4 ,capella1 how to find the ,north with1 #bd4 ,cardinal points of a compass1 #gh4 ,cassiopeia of the ,arabians1 #af4 constellation of1 #ad4 ,castor and ,pollux in ,gemini1 #agf4 ,cave man1 how he marked time1 #aeb4 ,central time1 #afj4 ,centrifugal force1 #eh1 #ij4 ,chromosphere1 the ,sun's1 #cb4 ,chronograph1 how made and used1 #afb4 ,chronometer1 use of1 to find longitude1 #he4 ,circle defined1 #aid4 ,colored stars1 #bjb4 ,colored sun glasses1 #cj4 ,colors1 how they are made1 #abc1 #abi4 ,combustion1 what it is1 #abc4 ,comet1 breaking up of1 #aaf4 coma of a1 #aac4 ,halley's1 #aae4 how to find a1 #aab4 nucleus of a1 #aac4 tail of a1 #aac1 #aaf4 ,comets1 laws of1 #aad4 number of1 #aaf4 paths of1 #aac4 speed of1 #aae4 ,compass1 boxing the1 #gh4 cardinal points of a1 #gh4 dial1 mariner's1 #gh4 how to make a simple1 #gg4 mariner's1 #gh4 pocket1 #gh4 ,concave lens1 #acd4 ,constellations3 ,aquarius1 the ,water ,bearer1 #fc4 ,aquila1 #bja4 ,aries1 the ,ram1 #fc1 #agc1 #age4 ,auriga1 #bc4 ,big ,dipper1 #f4 ,botes1 #bja4 ,cancer1 the ,crab1 #agf4 ,canis ,major1 #bh1 #bja4 ,cassiopeia1 #ad4 ,cygnus1 #bja4 ,flying ,horse1 #ai4 ,gemini1 the ,twins1 #fc1 #agf4 ,great ,bear1 #f4 ,great ,square of ,pegasus1 #ag4 having first magnitude stars1 #bja4 ,libra1 the ,balance1 #agh4 ,little ,bear1 #af4 ,little ,dipper1 #ae4 ,leo1 the ,lion1 #agg4 ,lyre1 #bja4 ,mighty ,orion1 #bj4 ,northern ,cross1 #bjb4 ,pisces1 the ,fishes1 #fc1 #agd4 ,pleiades1 #bf4 ,plough1 #f4 ,sagittarius1 the ,archer1 #ahj ,scorpio1 the ,scorpion1 #ahj4 ,taurus1 the ,bull1 #bd1 #age4 ,ursa ,major1 #f4 ,ursa ,minor1 #ag4 ,virgo1 the ,virgin1 #agg4 what they mean1 #ad4 ,zodiac1 #afh4 ,convex lens1 #acc4 ,copernicus on the ,moon1 #adh4 ,corona of the ,sun1 #cc4 ,crescent ,moon1 #ic4 ,cycle of the ,seasons1 #ge4 ,cygnus1 the ,swan1 #bja4 ,dark stars1 #bjf4 ,day1 solar1 #aed4 when it begins and ends1 #aeb4 ,definitions of words used in starcraft1 #bac4 ,degrees1 dividing a circle into1 #aef4 ,earth divided into1 #ha4 protractor for measuring1 #gi4 ,denebola in ,leo1 the ,lion1 #agg4 ,dial of mariner's compass1 #gi4 ,diameter defined1 #aid4 ,difference between true ,north ,pole and magnetic ,north ,pole1 #hh4 ,dipping needle1 how to make a1 #gi4 ,dog ,star1 #h4 ,double stars1 #bjd4 ,earth1 #dg1 #ed4 cross section of1 #fg4 divided into degrees1 #ha4 divided into standard meridians1 #aeh4 from the ,moon1 view of1 #ajd4 a great magnet1 #gg4 in the making1 #ff4 ,moon eclipsed by1 #ajg4 and ,moon joined together1 #hi4 orbit of1 an ellipse1 #gj4 precession of the1 #agc4 proof it is round1 #fg4 shadow of1 #aji4 thickness of air around1 #abe4 tilts on its axis1 #fi4 travels round the ,sun1 #gj4 turning of1 makes day and night1 #fi4 turning in orbit makes the seasons1 #gb4 turns on its axis1 proof that1 #fh4 umbra of1 #ace4 when cooled off1 #ff4 ,earth-shine1 #ic4 ,eastern time1 #aeh4 ,eclipse1 annular of the ,sun1 #aab4 ,eclipse1 defined1 #aac1 #aid1 #aie4 of the ,moon1 #ajg4 partial1 of the ,sun1 #aab4 seeing an1 #ajg4 of the ,sun by ,moon1 #aaj4 for next #cj years1 #aab4 total1 of the ,sun1 #aab4 ,ecliptic1 the1 #df1 #fi1 #gb1 #agj4 ,ellipse1 #aac4 ,ellis seasonal twilight chart1 #bja4 ,epsilon in ,lyra through a glass1 #aej4 ,equation of time1 #aee1 #bjg4 ,equator1 crossing the ecliptic1 #gb4 defined1 #aid4 ,equinox1 autumnal1 #agh4 vernal1 #agh4 ,ether1 what it is1 #abc1 #abe1 #abg4 ,evening star1 ,venus1 #ej4 ,experiment1 ,foucault's pendulum1 #fh4 in centrifugal force1 #ij4 making star trails1 #fh4 showing1 eclipse of ,sun1 #aaj4 how ,moon cracked1 #ade4 ,moon eclipsed by ,earth1 #ajg4 ,moon's crescent1 #ie4 ,moon's day and year1 #id4 ,moon's phases1 #ih4 reflection of light1 #aca4 refraction of light1 #acb4 with a bell1 #abe4 with candle to show the seasons1 #gc4 with cardboard zodiac1 #agj4 with spinning top1 #gb4 with water waves1 #abd4 ,eye1 a camera1 #abg4 how it sees1 #abg4 human1 #h4 light and1 #abi4 ,eyesight1 star tests for1 #aig4 ,finding1 the ,north ,star1 #b4 the ,north with ,pegasus1 #ai4 ,fireballs1 #aaf4 ,first magnitude stars1 #bjj4 ,fixed stars1 #g4 ,flying ,horse1 constellation of1 #ai4 ,focal length of a lens1 #acd4 ,focus of lens1 #acc4 ,forecasting the weather by barometer1 #ce4 ,forecasting weather by signs1 #cf4 ,foucault's pendulum experiment1 #fh4 ,fraunhofer's lines1 #aij4 ,frequency of vibrating atoms1 #abc4 ,friction1 #fj4 ,gemini1 the ,twins1 constellation of1 #fc1 #agf4 ,geometrical figures1 #aie4 ,gibbous ,moon1 #ic4 ,girl in the ,moon1 #adg4 ,gravitation defined1 #ei4 ,great ,bear1 #e4 ,great ,square of ,pegasus1 constellation of1 #ag4 ,greek alphabet1 #aig4 ,greenwich time1 #hf4 ,grimaldi on the ,moon1 #id1 #adg4 ,guardian stars of the ,little ,dipper1 #af4 ,handbook of ,boy ,scouts1 #aic4 ,harvest and ,hunter's ,moon1 #ih4 ,heat1 how it travels1 #abc4 ,heat1 what it is1 #abb1 #abi4 ,heliograph1 how to make and use a1 #dj1 #da4 ,horizon1 a good1 #aec4 ,horizon glass1 #hd4 ,horizontal line defined1 #aid4 ,horoscopes1 astrologer's1 #ahj4 ,horse and ,rider1 #aa4 ,hours1 dividing a circle into1 #aeg4 ,how a camera is made1 #ahe4 ,how the cave man marked time1 #aeb4 ,how the eye sees1 #abg4 ,how to find1 ,aries1 the ,ram1 #agd4 a comet1 #aac4 constellations of the ,zodiac1 #afi4 focus of a lens1 #acc4 longitude #hf4 the ,north ,star1 #hc4 with dipping needle and protractor1 #hb4 with sticks and pail of water1 #hc4 power of a telescope1 #adc4 ,how to get ,sun time1 #aec4 ,how to know1 the stars1 #ad4 you are at the ,north ,pole1 #hg4 ,how to look at the ,sun1 #adh4 ,how to make1 a cheap telescope1 #adj4 pinhole telescope1 #ach4 simple compass1 #gg4 simple dipping needle1 #gi4 star finder1 #a4 star trails1 #ahg4 ,how the ,moon makes the tides1 #ii4 ,how a photograph is made1 #ahe4 ,how a prism bends light1 #acc4 ,how to read the almanac1 #ahb4 ,how a spectroscope is made1 #aia4 ,how the stars shine1 #aba4 ,how the stars were made1 #aai4 ,how a telescope works1 #aci4 ,how to tell1 time by the ,big ,dipper1 #ab4 a true meteorite1 #aag4 ,how time is sent1 by telegraph1 #afc4 by wireless1 #afe4 ,how to use a prism1 #ahh4 ,how we see light1 #abf4 ,hyades in ,taurus1 #age4 ,hyperbola1 #aac4 ,imaginary ,sun time1 #aee4 ,index mirror1 #hd4 ,invisible stars1 #bjf4 ,jupiter1 #dg1 #fa4 nine moons of1 #eb4 seeing1 #ea4 through a telescope1 #adi4 ,kullmer star finder1 #bji4 ,latitude1 how to find1 by protractor and dipping needle1 #hb4 with sextant1 #hd4 with sticks and pail of water1 #hc4 ,lens1 concave1 #acd4 convex1 #acc4 how to find focus of a1 #acc4 ,leo1 the ,lion1 #agg4 ,libra1 the ,balance1 #agh4 ,light1 defined1 #abb4 how made1 #abb4 how it passes through glass1 #acj4 how it travels1 #abc4 how we see it1 #abf1 #abi4 reflection of1 #aca1 #acb4 refraction of1 #acb4 speed of1 #ahh4 what makes the colors in1 #abc4 wave-lengths of1 #abc1 #acj4 ,little ,bear1 constellation of1 #af4 ,little ,dipper1 constellation of1 #ae4 ,local time1 #hf1 #aee4 ,longitude1 how to find it1 #hf4 meridians of1 #hf4 use of sextant to find1 #hd4 ,lyra1 the ,lyre1 #bja4 ,magellan's voyage1 #fg4 ,magnet1 ,earth a great1 #gg4 ,magnet1 steel bar1 #gf4 ,magnetic lines of force1 #gf4 ,magnetic ,north ,pole and true ,north ,pole1 #gf1 #hh4 ,magnetic storms1 #cd4 ,magnitude of stars1 #aii4 ,man in the ,moon1 #ic4 ,mariner's compass1 #gh4 ,mars1 #dg1 #di4 is it peopled8 #di4 through a telescope1 #adi4 ,mean length1 defined1 #aed4 ,mean solar time1 #aed4 ,mean time1 #aeb4 ,mercury1 #dg1 #dh1 #fa4 phases of1 #dh4 through a telescope1 #adh4 ,meridian defined1 #ah4 prime1 #aef4 your1 #fa4 zero1 #aef4 ,meridians1 fixed1 #aeg4 of longitude1 #he4 standard1 #hf1 #aef4 ,meteorites1 kinds of1 #aag4 tests for1 #aag4 ,meteors1 and meteorites1 #aaf4 orbits of1 #aaf4 ,merit badge for starcraft1 #aic4 ,milk dipper in the ,milky ,way1 #aha4 ,milky ,way1 stars of the1 #aag1 #aah4 through a glass1 #aej4 ,mizar in the ,big ,dipper1 #aa1 #aej4 ,moon1 #hi4 ,apennines on the1 #adf4 aspects of the1 #id4 ,copernicus on the1 #adh4 crescent1 #ic4 day and year of the1 #id4 and ,earth joined together1 #hi4 eclipse of the1 #ajg4 eclipse of ,sun by the1 #aaj4 gibbous1 #ic4 ,grimaldi on the1 #id1 #adg4 ,harvest and ,hunter's1 #ii4 how it cracked1 #add4 if you were on it1 #aja4 imitating volcanoes on the1 #ia4 ,man in the1 #ic4 motions of the1 #id4 old1 in the new ,moon's arms1 #ic4 other things about the1 #ajf4 phases of the1 how made1 #id1 #ie1 #if4 photographing the1 #ahh4 seas on the1 #add4 seeing the1 with the naked eye1 #ib4 telling time by the1 #aje4 through a telescope1 #add4 time marked by the1 #aea4 a trip to the1 #aja4 ,tycho on the1 #add4 volcanoes on the1 #ia4 weather1 and the1 #aje4 where it came from1 #ij4 ,moon girl1 #adf4 ,morning star1 ,venus1 #ej4 ,morse ,code1 #ci4 ,motions of the ,moon1 #id4 ,mountain time1 #afj4 ,naked eye aids1 #aci4 ,naked eye view of the ,moon1 #ic4 ,nebula1 #aad1 #aah4 of ,orion1 great1 #aai4 ,nebular hypothesis1 #aai4 ,nebul1 different forms of1 #aai4 ,neptune1 the outpost planet1 #dg1 #ec4 seeing1 #ec4 through a telescope1 #adi4 ,north1 to find1 by a watch1 #de4 with ,capella1 #bd4 with ,orion1 #bc4 with ,pegasus1 #ai4 ,north magnetic pole1 #gf4 ,north ,pole1 #h4 explorers at the1 #hg4 how to know you are at1 #hg4 shadows at1 #hh4 true1 and magnetic ,north ,pole1 #gf1 #hh4 ,north ,star1 #a1 #b1 #d4 how to find1 #a1 #b4 how to find latitude of1 #hc4 sighting the1 #b4 through a glass1 #aej4 ,northern ,cross1 #bjb4 ,northern ,lights1 #cd4 ,old ,farmers' ,almanac1 #ahd4 ,old ,moon in the new ,moon's arms1 #ic4 ,opera glasses1 #adj4 ,optic nerve1 #abf4 ,orion1 of the ,arabians1 #bb4 belt of stars of1 #ba4 constellation of1 #bj4 finding the ,north with1 #bc4 the ,great ,hunter1 #bj4 ,great ,nebula of1 #aai4 sword of stars of1 #bb4 ,pacific time1 #afj4 ,parabola1 #aac4 ,partial eclipse of the ,sun1 #aab4 ,pegasus1 the ,flying ,horse1 #ai4 ,pendulum illustrating ,sun's attraction1 #ei4 ,penumbra1 #ace4 ,perpendicular line defined1 #aid4 ,phases1 of ,mercury1 #dh4 of ,venus1 #ej4 ,photograph1 how made1 #ahe4 ,photographing the ,moon1 #ahh the stars1 #ahe4 ,photographing the ,sun1 #ahg4 ,photosphere of the ,sun1 #cb4 ,pinhole sunshade1 #cj4 ,pinhole telescope1 #cj1 #ach4 ,pisces1 the ,fishes1 constellation of1 #fc1 #agd4 ,plane1 defined1 #ee4 ,planet1 how to plot position of a1 #fa4 ,planetesimal hypothesis1 #aai1 #abj4 ,planets1 eggshell experiment to show motions of1 #eg4 first aid to remembering1 #eg4 how held in space1 #eg4 how to know the1 #dg4 names and sizes of1 #dg4 path of1 #agj4 plane of1 #ee4 round the ,sun1 position of1 #ed4 the ,sun's kiddies1 #df4 through a telescope1 #adh4 use of almanac for finding1 #fa4 why they spin1 #fj4 ,pleiades1 in ,taurus1 #bf4 through a glass1 #aej4 ,plotting the position of a planet1 #fa4 ,plough1 the1 #e4 ,pointer stars of the ,big ,dipper1 #aj4 ,polar nights1 #ga4 ,polaris1 the ,pole ,star1 #d4 ,pole ,star1 the1 #d1 #h4 ,precession of the ,earth1 #agc4 ,prime meridian1 #aef4 ,prism1 #acb4 forming a spectrum1 #acd4 how to use1 #ahh4 ,produce1 defined1 #h4 ,prominences of the ,sun1 #ca4 ,protractor1 showing degrees1 #ha4 showing degrees latitude1 #hb4 ,radius defined1 #aid4 ,railroad time1 #aef4 ,reflection of light1 #aca4 ,regulus in ,leo1 the ,lion1 #agg4 ,rigel in ,orion1 #bh4 ,right angle defined1 #aid4 ,ring defined1 #aid4 ,sagittarius1 the ,archer1 #ahj4 ,saturn1 #dg4 seeing1 #eb4 through a telescope1 #adi4 ,scorpius1 the ,scorpion1 #ahj4 ,seasonal twilight chart1 ,ellis1 #bja4 ,seasons3 autumn1 #gd4 spring1 #gd4 summer1 #ge4 winter1 #gd4 cycle of the1 #ge4 ,earth turning round ,sun makes the1 #gb4 experiment to show the1 #gc4 ,seeing1 an eclipse1 #ajg4 the ,moon with naked eye1 #ib4 the stars1 #aba4 ,sextant1 how to use it1 #hd4 ,shadow of1 the ,earth1 #aji4 the ,penumbra1 #ace4 the ,umbra1 #ace4 ,shadows1 #ace4 at the ,north ,pole1 #hh4 ,shooting the ,sun1 #hd4 ,shooting stars1 #aaf4 ,sighting the ,north ,star1 #b4 ,signalling with the ,sun's rays1 #ch4 ,signs1 in the almanac1 #ahc4 of the ,zodiac1 #afh4 ,sirius1 the ,dog ,star1 #h1 #aah4 ,sky1 things in the1 #ajg4 ,smoked ,sun glasses1 #cj4 ,solar day1 #aed4 apparent1 #aed4 ,solar noon1 #aec4 ,solar spectrum1 #ahi4 ,solar system1 in perspective1 #ef4 top view of1 #ee4 ,solar time1 #aeb4 mean1 #aed4 ,solstice1 summer1 #agf4 winter1 #aha4 ,sound waves1 #abe4 ,south ,pole1 #bf4 ,spectroscope1 #ahi4 how made1 #aia4 ,spectrum1 #acc4 solar1 #ahi4 ,spring1 #gd4 ,spyglass1 #acf4 stars seen through1 #add4 ,standard meridians1 #hf1 #aef4 ,standard time1 #aee4 zone system of1 #aef4 ,standard time meridians in ,united ,states1 #aei4 ,starcraft1 merit badge for1 #aic4 ,star finder1 how to make a1 #a4 ,kullmer1 #bji4 ,star tests for eyesight1 #aig4 ,star time1 #afj4 ,star trails1 how to make1 #ahg4 ,stars1 colored1 #bjb4 constellations having first magnitude1 #bja4 double1 #bjd4 first magnitude1 #bjj4 how made1 #aai4 how they shine1 #aba4 invisible or dark1 #bjf4 magnitude of1 #aii4 near the ,sun's path1 #fb4 photographing1 #ahe4 seeing1 #aba4 through a telescope1 #adi4 variable1 #bje4 what they are made of1 #ahh4 of the ,zodiac1 #aff4 ,straight line defined1 #aid4 ,summer1 #ge4 ,summer solstice1 #agf4 ,sun1 annular eclipse of the1 #hg4 arctic1 #hg4 attraction of1 illustrated1 #ei4 brightest star1 #bi4 hot gases of1 #aba4 chromosphere of1 #cb4 core of1 #cb4 corona of1 #cc4 cross section of1 #cd4 eclipse of1 by the ,moon1 #aaj4 how to see1 #bi4 layers of flame of1 #ca4 lighting a fire with1 #cg4 from the ,moon1 view of1 #ajd4 stars near the1 #fb4 partial eclipse of the1 #aab4 path of the1 #df1 #agj4 photographing the1 #ahg4 photosphere of1 #cb4 positions of planets round the1 #ed4 prominences of1 #ca4 rays of1 signalling with1 #ch4 shooting the1 #hd4 surface of1 #cb4 time marked by1 #aea4 through a telescope1 #adh4 weather and1 #cd4 what it is made of1 #cj4 ,sun dial1 how to make a simple1 #db4 ,sun spots1 #ca4 effects of1 on the ,earth1 #cc4 ,sun time1 #aeb4 how to set1 #aec4 imaginary1 #aee4 ,sword of ,orion1 #bb4 ,tangent defined1 #eh1 #aid4 ,taurus1 ,aldebaran in1 #bf4 constellation of1 #bd1 #fc1 #age4 of the ,egyptians1 #bf4 ,telescope1 #acf4 astronomical1 #ach4 with convex lenses1 #adb4 defined1 #acf4 discovery of1 #acf4 equatorial1 #ahh4 how to make a cheap1 #adj4 how to make a pinhole1 #ach4 how it works1 #aci4 kinds of1 #acg1 #aci4 magnifying power of1 #adc4 ,mars through a1 #adi4 ,mercury through a1 #adh4 ,moon through a1 #add4 ,neptune through a1 #adi4 opera glass1 #ada4 pinhole1 #cj4 planets through a1 #adh4 ,saturn through a1 #adi4 seeing the stars through a1 #add4 of sextant1 #hd4 simple1 #adj4 stars through a1 #adi4 ,sun through a1 #adh4 ,uranus through a1 #adi4 ,venus through a1 #adh4 ,telescope lens1 mounting for1 #adj4 ,test for eyesight1 ,alcor1 #aa4 ,tides1 high and low1 #ajj4 how the ,moon makes1 #ii4 spring and neap1 #aja4 ,time1 apparent1 #aeb4 at different cities1 #afa4 by the ,moon1 telling1 #aje4 by the stars1 #afj4 central1 #afj4 to change star1 into solar1 #afc4 correct1 #afa4 how obtained1 #afb4 distributed by telegraph1 #afa4 by wireless1 #afa4 eastern1 #aeh4 equation of1 #aee1 #bjg4 ,greenwich1 #hf4 how sent by telegraph1 #afc4 how to tell1 by the ,big ,dipper1 #ab4 imaginary ,sun1 #aee4 local1 #hf1 #aee4 marked by the ,moon1 #aea4 by the ,sun1 #aea4 mean1 #aeb4 solar1 #aed4 mountain1 #afj4 o' day1 #aea4 ,pacific1 #afj4 railroad1 #aef4 standard1 #aee4 ,sun1 #aed4 what is it8 #aea4 zone system of standard1 #aef4 ,time ball1 how made and worked1 #afd4 ,time meridians in ,united ,states1 standard1 #aei ,total eclipse of the ,sun1 #aaj4 ,transit of a star1 #afb4 ,transit instrument1 #afb4 ,trapezium defined1 #bj1 #ba4 ,true ,north ,pole1 #gf4 ,tycho on the ,moon1 #add4 ,umbra of the ,moon1 #ace4 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