,transcriber's ,note ,italic text displayed as3 italic ,,popular ,,lessons ,,in ,,astronomy1 ,,on ,a ,,new ,,plan2 ,,in ,,which ,,some ,,of ,,the ,,leading ,,principles ,,of ,,the ,,science ,,are ,,illustrated ,,by ,,actual ,,comparisons1 ,,independent ,,of ,,the ,,use ,,of ,,numbers4 ,,by ,,francis ,j4 ,,grund1 ,,author ,,of 8,,an ,,elementary ,,treatise ,,on ,,plane ,,and ,,solid ,,geometry10 8,,elements ,,of ,,natural ,,philosophy ,,and ,,chemistry10 c4 ,illustration3 ,decoration ,,boston ,,carter1 ,,hendee ,,and ,,co4 #ahcc4 ,,entered according to ,act of ,congress1 in the year #ahcc1 ,by ,,francis ,j4 ,,grund1 in the ,clerk's office of the ,district ,court of ,massachusetts4 ,i4 ,r4 ,,butts1 ,,school ,,street4 ,,notice4 ,the ,geographical ,miles1 which are used in the scales and tables of this book1 are ,german ,geographical ,miles1 of which #ae make one degree4 ,the teacher or pupil may easily change them into ,english ,geographical ,miles1 by multiplying them by #d1 the square miles by #af1 and the cubic miles by #fd4 ,,preface4 ,although many elementary works on ,astronomy are already before the public1 yet it is believed there is none in which the various magnitudes1 surfaces1 and distances of the heavenly bodies1 are presented to the eye of the learner by actual comparisons2--the only way1 perhaps1 in which young pupils can be expected to form a correct idea of them4 ,this the author has attempted in the following pages4 ,the comparative diameters1 surfaces and distances of the different planets1 are all drawn1 in the plates1 according to a fixed scale of geographical miles2 the surfaces of the planets are actually reduced to square measure1 and drawn in proportion to each other and the sun2 so that the youngest pupil1 by a mere glance of the eye1 is enabled to form a correct idea of their respective magnitudes4 ,a similar plan has been pursued1 in regard to the division of the ,earth into ,zones1 and with respect to the extent of the five great ,continents of our ,globe4 ,the ,appendix contains an exposition of the population of ,america1 ,europe1 ,asia1 ,africa1 and ,australia1 accompanied by a plate for the illustration of the comparative settlements on those ,continents4 ,boston1 ,june #bd1 #ahcc4 ,,popular ,,lessons ,,in ,,astronomy4 ,,lesson ,i4 ,,the ,,earth ,,in ,,its ,,relation ,,to ,,the ,,sun1 ,,moon ,,and ,,stars4 #a4 ,the ,earth on which we live1 and on which plants1 trees and animals successively live and die1 is only a small part of the world2 it is but one of the smallest bodies in the ,universe4 ,to the world belong yet the ,sun from which we receive warmth and light1 the ,moon1 and an innumerable class of bodies1 which1 at night1 appear to us as so many points of light4 ,these are called ,stars4 ,the reason why the ,stars appear to us so small1 is because they are so far from us2 and things appear smaller in proportion as they are farther removed from us4 ,this you will have noticed1 when looking from a high steeple on the people below1 or on a vessel far out in the harbour1 or on a chain of mountains at a great distance4 #b4 ,most all ,stars appear to us1 every night in the same position2 they seem actually to be fixed in the heavens2 and for this reason they are called fixed ,stars4 ,there are however ,ten others1 of which it has been ascertained that they move regularly round the ,sun in large circles4 ,these are called ,planets or wandering ,stars4--,the fixed ,stars are supposed to be similar to the ,sun1 in as much as they are bodies which have their own light4 ,the ,planets1 on the contrary1 are of themselves dark bodies1 and receive1 like our ,earth1 light and warmth from the ,sun4 ,we see them only in consequence of the solar light which they reflect from their surfaces1 and this is the reason why they appear to us as bright as the other ,stars4 #c4 ,the discoveries of ,philosophers have proved beyond a doubt1 that our ,earth itself is one of those ,planets1 which move round the ,sun in stupendous large circles1 whose grandeur is hardly conceived by the most powerful imagination4 ,our ,earth1 therefore1 is1 itself1 a ,wandering ,star1 and the line in which it moves round the ,sun is called its ,way or ,orbit4 #d4 ,the ,planets1 together with our ,earth keep each a certain fixed distance from the ,sun4 ,on this account they do not disturb each other in their orbits4 ,but they vary from each other in magnitude2 although all of them 7consequently also our ,earth7 have a round shape1 similar to a ball4 ,in former times men believed that the ,earth was flat1 or a circular plate on all sides surrounded by water4 ,but this is not true4 ,for it has been proved by a great many observations and actual measurements1 that the ,earth has a spherical 7ball-like7 form4 ,moreover there are navigators who have actually sailed round the world1 and who have noticed the fact that at sea1 the tops of distant objects are seen sooner than the rest2 which again proves the spherical form of our ,earth4 ,for an illustration you may look at the adjoining plate ,plate ,no4 ,i4 ,the man who is represented as standing on a portion of our ,earth1 will at first only see the topmast of a vessel at sea2 when she comes nearer his eye will discover a much greater portion of her2 but when in the third position every part of the vessel will be visible4 #e4 ,some of the ,planets are1 in their motion round the ,sun1 accompanied by other dark bodies1 which1 like the ,planets themselves1 receive light and heat from the ,sun4 ,these are called ,satellites or ,moons4 ,such a ,satellite is the ,moon which accompanies our ,earth2 and there are ,planets 7as we shall see hereafter7 which have ,four and ,six1 and ,one that has even ,seven ,moons4 #f4 ,besides the ,planets and ,moons there is yet another class of bodies1 moving round the ,sun in exceedingly long ovals4 ,they are but seldom visible1 and are distinguished from other heavenly bodies by a tail which is often three1 four1 and more times larger than the body itself4 ,these are called ,comets2 but their number has not1 as yet1 been precisely ascertained4 #g4 ,the ,planets1 ,moons and ,comets1 together with the ,sun around which they move1 form what is called our ,solar ,system4 ,but what will you say1 if you are told that each fixed ,star in the firmament is a ,sun which1 like our's1 has its ,planets and satellites and ,comets2 in short1 that each fixed ,star is the centre of a solar system1 a thousand and more times larger than our own66 ,but how infinitely great must ,god's ,creation appear to us1 when we reflect that all these globes1 as well as our own1 may be inhabited by reasonable beings666 ,illustration3 ,no4 ,i4 ,,recapitulation ,,of ,,lesson ,i4 ,if the pupil has learned and understood this lesson1 it may perhaps be not unreasonable to suppose he will like to know something more about the ,planets and the ,moons in our system4 ,but the teacher ought not to allow him to enter upon the second lesson1 before he has recapitulated the first4 ,,questions4 #a4 ,does the ,earth1 or the globe on which we live1 comprise the whole world which ,god has created8 ,is our ,earth any considerable portion of the ,universe8 ,what other bodies belong to it8 ,why do the ,stars appear to us so small8 #b4 ,do all the ,stars which we see remain in the same position8 ,what are those called which remain fixed8 ,what1 those1 which are moving regularly round the ,sun8 ,what are the fixed ,stars supposed to be8 ,have the ,planets any light of their own8 ,from what body do the ,planets receive their light8 #c4 ,what important discoveries have ,philosophers made respecting the nature of our ,earth8 ,what is the line in which our ,earth moves round the ,sun1 called8 #d4 ,why do the orbits of the different ,planets not disturb each other8 ,are all ,planets of the same magnitude8 ,what is their shape8 ,what is the shape of our ,earth8 ,what reason have you to believe1 that the ,earth is round8 ,explain ,plate ,i8 #e4 ,by what are some ,planets in their motion round the ,sun accompanied8 ,what are the bodies which accompany them called8 ,what body accompanies our ,earth in its motion round the ,sun8 ,are there ,planets which have more than ,one ,moon8 #f4 ,what other class of bodies is there1 besides the ,planets and the ,moons8 ,are these bodies always visible8 ,by what are these bodies distinguished8 ,what are they called8 #g4 ,what do the ,planets1 ,moons and ,comets1 together with the ,sun1 round which they move1 form8 ,what is each fixed ,star supposed to be8 ,,lesson ,,ii4 ,,of ,,the ,,planets ,,and ,,their ,,relative ,,position ,,with ,,regard ,,to ,,the ,,sun ,,and ,,each ,,other4 #h4 ,the ,planets of which we have spoken in the ,first ,lesson are ,eleven in number1 of which each has received a proper name4 ,they are in the order in which they are placed from the ,sun1 the following3 ,mercury4 ,venus4 ,the ,earth4 ,mars4 ,vesta4 ,juno4 ,ceres4 ,pallas4 ,jupiter4 ,saturn4 ,herschel4 ,the adjoining diagram1 on ,plate ,no4 ,,ii1 may serve for an illustration4 ,you will see from it1 that the ,earth is the third ,planet from the ,sun4 ,mercury and ,venus come before it2 the most remote from the ,sun is ,herschel1 so called from the astronomer's name1 who has but lately discovered it4 #i4 ,the ,earth is constantly attended by ,one ,satellite 7,lesson ,i1 #e72 ,jupiter by ,four 7see the diagram71 ,saturn by ,six1 and ,herschel by ,seven4 ,saturn is1 besides1 constantly surrounded by a broad luminous ring1 which distinguishes it from all other ,planets1 and of which we shall speak hereafter4 #aj4 ,with regard to the magnitude of the different ,planets it has been observed that although some of them are much larger than ,our ,earth2 yet in ,comparison to the ,sun they are but small bodies1 as you may see from the figures on plate ,no4 ,,iii1 in which the different ,planets are drawn in proportion to the ,sun3 you will perceive from it2 #a4 ,that the ,sun is a great many times#a larger than either of the ,planets4 ,illustration3 ,no4 ,,ii4 ,illustration3 ,no4 ,,iii44 #b4 ,that the ,sun is much larger than all the ,planets 7our ,earth included7 taken together4 #c4 ,that ,jupiter is the greatest ,planet in our solar system4 #d4 ,that ,saturn is the second ,planet with regard to magnitude4 #e4 ,that ,herschel ranks third4 #f4 ,that the ,earth ranks fourth2 but that #g4 ,each of the other ,planets and the ,moon are smaller than the ,earth4 #h4 ,that either of the ,planets ,ceres1 ,vesta1 ,juno1 ,pallas is smaller than the ,moon4 #aa4 ,if you cut a ball or a sphere in halves1 and through the centre of one of the flat surfaces1 draw a straight line across the whole surface1 then this line is called the ,diameter of the ball or sphere4--,now as the ,sun and the ,planets are nothing else but large balls or spheres 7,lesson ,i1 #d71 we may also speak of their ,diameters4--,thus we say1 8the ,diameter of the ,sun is so many times larger than that of the ,earth2 the ,diameter of ,jupiter is so many times larger than that of ,venus10 etc4 ,you will now easily understand what the straight line means1 which1 in plate ,no4 ,,iii is drawn through the centre of the circle1 which represents the ,sun2 also the straight lines which are drawn through the circles which represent the ,planets4--,you will also perceive from the first figure on plate ,no4 ,,iii1 that the ,sun's ,diameter is larger than the ,diameters of all the ,planets taken together4 #ab4 ,plate ,no4 ,,iv represents the surfaces of the ,planets1 compared to that of the ,sun4--,for you must know that it is possible to measure the surface of a sphere2 which is done by supposing it to be spread out1 and then seeing how many square inches1 feet or yards it contains4 ,this we have supposed to be done with the surfaces of the ,sun and ,planets1 and accordingly1 have drawn their square measurements1 in ,plate ,no4 ,,iv4 in proportion to each other4 ,you will see from this ,plate3 #a4 ,that the square-,contents of the ,sun's surface is greater than that of the surfaces of all the ,planets taken together4 #b4 ,that the square-,contents of the ,earth's surface is nearly as large as that of the surfaces of ,mercury and ,venus taken together4 ,illustration3 ,no4 ,,iv4 #c4 ,that the square-,contents of the surfaces of ,vesta1 ,ceres1 ,juno and ,pallas1 taken together1 is not yet sufficient to cover the surface of our ,earth4 #d4 ,that the square-,contents of ,jupiter's surface is larger than that of the surface of any other ,planet4 #e4 ,that the square-,contents of ,jupiter's surface is greater than that of the surfaces of all other ,planets taken together4 #f4 ,that ,saturn's surface is the next largest4 #g4 ,that ,herschel's is still larger than those of our ,earth1 ,venus and ,mercury taken together4 #h4 ,that the square-,contents of the ,moon is nearly as large as that of the surfaces of ,ceres1 ,vesta and ,juno1 taken together2 and that it is larger than that of ,pallas' surface taken alone4 ,in order that you may be better able to compare1 you will find on ,plate ,no4 ,v #a4 ,the surfaces of the different ,planets1 all drawn upon the ,sun's surface2 from which you may see1 how much larger the ,sun's surface is than the surfaces of all the ,planets and the ,moon taken together4 #b4 ,the surface of the ,earth compared to that of ,mercury and ,venus4 #c4 ,the ,earth's surface compared to that of the ,four ,asteroids ,pallas1 ,ceres1 ,juno and ,vesta4 #d4 ,jupiter's surface compared to those of all the other ,planets4 #e4 ,the square-,contents of the ,moon compared to the surfaces of ,vesta1 ,juno and ,ceres4 #f4 ,herschel's square-,contents compared to that of our ,earth1 ,venus and ,mercury taken together4 #ac4 ,the ,four ,planets1 ,ceres1 ,vesta1 ,juno1 and ,pallas1 are so small in proportion to the other ,planets1 and are so near each other 7they are almost at the same distance from the ,sun--see ,plate ,,ii7 that many distinguished philosophers are of opinion1 they are but the fragments of ,one large ,planet1 which1 from some cause or other1 has burst4--,but this is no subject for us now to inquire into2--we will therefore proceed to describe in the next lesson1 the motion of the different ,planets round the ,sun4 ,illustration3 ,no4 ,v4 ,,recapitulation ,,of ,,lesson ,,ii4 ,,questions4 #h4 ,what are the names of the ,eleven ,planets in the order in which they are placed from the ,sun8 ,how many ,planets are there between the ,earth and the ,sun8 ,how many ,planets come after our ,earth8 ,in what order then1 is our ,earth placed among the ,planets8 7,is it the first1 second1 etc4 from the ,sun78 #i4 ,how many satellites accompany our ,earth8 ,what is it called8 ,how many satellites or ,moons has ,jupiter8 ,how many has ,saturn8 ,how many has ,herschel8 ,by what is ,saturn particularly distinguished from all other ,planets8 #aj4 ,are all ,planets of the same magnitude as our ,earth8 ,are the ,planets in comparison to the ,sun large or small bodies8--,is the ,sun much larger than any of the ,planets8 ,is the ,sun larger or smaller than all the ,planets1 including our ,earth1 taken together8 ,which is the greatest of all ,planets8 ,which ,planet ranks1 in magnitude1 next to ,jupiter8 ,which of the ,planets ranks third in magnitude8 ,which1 ,fourth8 ,what ,planets are smaller than our ,earth8 ,what ,planets are smaller than the ,moon8 #aa4 ,what do you call the ,diameter of a ball or sphere8 ,is the ,diameter of the ,sun larger or smaller than the ,diameters of all the ,planets taken together8 ,the teacher may yet ask a number of questions respecting the ,diameters of the ,planets1 which the pupil will be able to answer by looking on ,plate ,,iii4 ,he may1 for instance1 ask whether the ,diameter of the ,earth is larger or smaller than that of ,venus8 ,whether the ,diameter of ,jupiter or ,saturn is the largest1 etc48 ,this will oblige the pupil to compare the different magnitudes of the ,planets and their ,diameters4 #ab4 ,what proportion does the square-,contents of the ,sun's surface bear to that of the surfaces of all the ,planets8 ,what two ,planets have together a surface nearly as large as that of our ,earth8 ,are the surfaces of ,ceres1 ,vesta1 ,juno and ,pallas taken together sufficient or not1 to cover the surface of our ,earth8 ,what ,planets1 therefore1 could be covered with the ,earth's surface8 ,which ,planet has the largest surface8 ,what do you observe with regard to the square-,contents of ,jupiter's surface8 and that of the surfaces of all other ,planets1 taken together8 ,what ,planet's surface comes next in magnitude to ,jupiter's8 ,what ,planet's surface is larger than that of our ,earth1 ,venus and ,mercury taken together8 ,what three ,planets' surfaces taken together are smaller than that of the ,moon8 ,what ,planet has nearly as large a surface as the ,moon8 #ac4 ,what is the opinion of philosophers respecting the ,four ,planets1 ,ceres1 ,vesta1 ,juno and ,pallas8 ,,footnotes3 #a ,numbers are purposely omitted here1 because abstract numbers convey little or no ideas to young pupils4 ,those who wish these relations expressed in numbers will find them in ,table ,i at the end of the book4 ,,lesson ,,iii4 ,,explaining ,,the ,,motion ,,of ,,the ,,planets ,,and ,,comets ,,round ,,the ,,sun4 #ad4 ,you have learned1 in the preceding lesson1 that the ,earth and the other ,planets are regularly moving round the ,sun2 but you must know that the time which each requires to complete a whole revolution1 that is1 the time which each needs to move once round1 cannot be the same with all2 as you may easily judge yourself3 for the ,planets which are next to the ,sun will1 of course1 have a much smaller journey to perform1 than those which are further from it4 ,thus ,mercury1 which is the first ,planet in order from the ,sun1 will naturally come round much sooner than ,jupiter1 which is placed at a much greater distance from it4 ,that you may the easier understand this1 the following ,plate1 ,no4 ,,vi1 will represent to you our ,solar ,system3 ,the ,sun from which proceeds all light and heat1 is placed in the centre4 ,then come the ,planets ,mercury and ,venus2 ,third in order is our ,earth with its ,satellite the ,moon2 and so on4 ,the rest of the ,planets in the same order in which they are represented on ,plate ,,ii4 ,you will also perceive there the orbs of two ,comets1 distinguished as you were told1 by a tail of light4 ,the ,planets ,jupiter1 ,saturn and ,herschel are each represented with their ,moons1 and the ,planet ,saturn with its luminous ring4 ,illustration3 ,no4 ,,vi4 ,now you will easily understand that ,ceres1 ,vesta1 ,juno1 ,pallas1 ,mars1 ,jupiter1 ,saturn and ,herschel1 have each a much greater distance to travel1 than our ,earth2 but that1 on the contrary1 ,venus and ,mercury can complete their revolution in a much shorter time4#b #ae4 ,the time which our ,earth needs to travel once completely round the ,sun1 7to finish one revolution7 is called a ,year4 ,such a year has three hundred and ,sixtyfive days2--and each of these days has again ,twentyfour hours4 ,you see from this that the revolution of the ,earth round the ,sun gives us a means of measuring time1 by which we are able to bring order and regularity into our business and transactions of life4 ,for the making of clocks and watches is but a late invention1 and we should be left entirely in the dark as regards the history of former ages1 and a great many people would1 at this present moment1 be incapable of forming a correct estimate of time1 if ,providence had not given to all this appropriate means of measuring it4 #af4 ,while the ,earth needs a whole year for one revolution round the ,sun2 ,mercury requires but ,eightyone days1 and ,venus only about two thirds of ,one of our years4 ,mars1 on the contrary1 needs for one of his revolutions almost ,two years2 ,vesta almost ,four2 ,juno1 ,ceres and ,pallas over ,four years2 ,jupiter almost ,twelve1 ,saturn over ,twentynine1 and ,herschel nearly ,eightyfour of our years6#c--;,and if these ,planets1 as we have reason to believe1 are inhabited by beings endowed with human understanding and faculties1 numbering their years as we do ours--by the revolution of their ,planets round the ,sun--how different from ours must be the ,period of their existence66 #ag4 ,during the time that the ,earth is performing her journey round the ,sun1 the ,moon1 our constant attendant1 is continually moving round the ,earth1 and completes one of these revolutions in little more than ,twentyseven days4--,very important and interesting to us are the changes in appearance which she exhibits during each of these revolutions4--,you probably will know1 that the ,moon does not appear to us1 at all times1 the same4 ,sometimes she is hardly at all visible1 7at least not with the naked eye72 at other times only a small rim of her is seen1 which by degrees becomes larger and larger1 until finally she appears in her full round form4 ,after this she begins again to diminish1 changes again into a small luminous rim1 and finally disappears entirely from our sight4 ,these successive changes in the ,moon's appearance are called the ,moon's ,phases1 or the waxing and waning of the ,moon4 ,the time during which the ,moon is not seen is called ,new ,moon2 the time during which she exhibits her full shape is called the ,full ,moon2 and the different periods of her waxing and waning 7when she appears to us in the form of a crescent7 are called ,quarters4 ,thus we speak of the ,first and of the ,last ,quarter of the ,moon4 ,the ,first ,quarter takes place after ,new ,moon2 the last ,quarter after ,full ,moon4 ,the following diagram1 ,plate ,no4 ,,vii1 may serve to represent to you the ,moon's phases as seen from our ,earth4 ,when the ,moon is in a1 then the light of the ,sun falls just on that side of it which is turned from the ,earth4 ,it is then1 we have ,new ,moon4 ,when in b1 a small brim of the ,moon is seen1 because a small portion of its lighted surface is then turned towards the ,earth4--,when in c half of her lighted surface is turned towards us1 and we have the ,first ,quarter4 ,in d a still greater portion of the ,moon's lighted surface is visible1 and in e1 we have ,full ,moon1 because her whole lighted surface is then turned towards the ,earth4 ,in f the moon commences to wane 7to grow smaller17 and in g the last quarter commences2 finally1 when passed through the point h1 we have in a1 again ,new ,moon4 ,for familiar illustration you may also take a white ivory ball1 holding it before a lighted candle1 which may take the place of the ,sun4 ,when the ball is in a straight line between your eye and the candle it will appear to you all dark2 because the lighted part is then entirely turned toward the candle 7away from you71 and you have the same case which is represented to you in the diagram1 when the ,moon is in a4 ,but if you move the ball a little to the right1 you will perceive a streak of light1 similar to the ,first ,quarter represented in the ,diagram1 when the ,moon is in c4 ,if moved still farther to the right1 so that the whole lighted part of the ball is seen1 it will resemble the ,full ,moon2 represented in the ,diagram1 when the ,moon is in e4 ,illustration3 ,no4 ,,vii4 ,illustration3 ,no4 ,,viii4 #ah4 ,while the ,moon is moving round the ,earth1 it often occurs that she is placed in a direct line between ourselves and the ,sun4 ,in this case a greater or less part of the ,sun is concealed from us1 which causes a diminution of light or a partial darkness on our ,earth4 ,this we call an ,eclipse of the ,sun4 7,such an ,eclipse took place in #ahca1 and you will probably have an opportunity of seeing many more74 ,if1 on the contrary1 the ,earth is placed in a direct line between the ,sun and the ,moon1 then the ,moon will be obscured by our ,earth4 ,this is called an ,eclipse of the ,moon4 ,the following two figures on ,plate ,no4 ,,viii will serve for an illustration4 ,you will easily perceive from them that if the ,moon 7as represented in ,figure ,i7 is placed in a direct line between the ,sun and ourselves1 it must necessarily conceal from us part of that luminary2 and in this state cast a shade upon our ,earth4 ,but if the ,earth is placed in a direct line between the ,sun and the ,moon1 7as represented in ,figure ,,ii71 then the ,moon will be much more obscured1 because the ,earth is much larger than the ,moon1 and will therefore cast a much greater shade upon her4 #ai4 ,it remains for us to speak of that class of bodies known by the name of ,comets1 7see ,lesson ,i1 #f74 ,of these an unknown number belongs to our ,solar ,system4--7,some philosophers have estimated their number to be about ,twentyone2 others think it must amount to several hundred74 ,they move round the ,sun in exceedingly long ovals1 having their transparent tails always turned away from that luminary4 ,what is most remarkable about them is the astonishing degree of heat to which they are exposed on account of passing so near the ,sun1 and the astonishing velocity with which they travel4 ,the ,comet which appeared in the year #afhj1 is supposed to sustain a heat nearly ,two ,thousand times greater than that of red hot iron1 and to move at the rate of several ,hundred ,thousand miles an hour66 ,,recapitulation ,,of ,,lesson ,,iii4 ,,questions4 #ad4 ,do all ,planets need the same time to complete a whole revolution round the ,sun8 ,why not8 ,if the pupils are old enough to understand the use of ,dividers1 it will perhaps be well for the teacher to let them draw the ,solar ,system on a piece of paper4--,if not1 he ought to let them explain ,plate ,,iv1 or an orrery1 if one be at hand4 #ae4 ,what is the time called1 which our ,earth needs for a complete revolution round the ,sun8 ,how many days are there in a year8 ,how many hours are there in a day8 ,what is the revolution of the ,earth round the ,sun1 the means of8 #af4 ,what time does ,mercury require for a complete revolution round the ,sun8 ,what time does ,venus require for the same purpose8 ,what time does ,ceres1 ,vesta1 ,juno and ,pallas need8 ,what1 ,jupiter1 ,saturn1 and ,herschel8 #ag4 ,what motion does the ,moon make whilst the ,earth is travelling round the ,sun8 ,how many days does the ,moon need for a complete revolution round the ,earth8 ,does the ,moon during its revolution round the ,earth always exhibit the same shape8 ,what changes then does she gradually undergo8 ,what do you call the successive changes in the ,moon's appearance8 ,what do you call the time during which the ,moon is not seen8 ,what1 that1 during which she exhibits her full shape8 ,what1 the different periods of her waxing and waning8 ,when does the ,first ,quarter take place8 ,when the last8 ,the teacher might now require the explanation of ,plate ,v2 the elder pupils may draw the ,diagram4 #ah4 ,what does frequently occur during the ,moon's motion round the ,earth8 ,what is the consequence of the ,moon's position in a direct line between the ,sun and ourselves8 ,what is such a diminution of light in consequence of the ,moon being placed between us and the ,sun1 called8 ,what takes place when the ,earth is placed between the ,sun and the ,moon8 ,what is such an obscuration of the ,moon1 in consequence of the ,earth's position between her and the ,sun1 called8 ,the younger pupils ought now to explain ,plate ,,viii2 the elder pupils ought to draw the ,diagram on a slate or paper4 #ai4 ,is the number of ,comets belonging to our ,solar ,system precisely ascertained8 ,how many are there supposed to belong to our ,system8 ,in what manner do they move round the ,sun8 ,what remarkable property do they possess8 ,,footnotes3 #b ,if the teacher has an orrery at hand1 if it be even of the most simple construction1 he may exhibit it now4 ,but it is the author's belief that a considerable portion of the pupil's interest is lost1 if he be acquainted with it1 at the beginning of the study2 or1 as it is the custom in some schools1 if an orrery is hung up among the charts and maps of the school room4 ,the pupil ought not to see the orrery1 until he knows that it is but a faint illustration of the infinite grandeur of the heavens4 ,nothing detracts so much from our estimation of things as a too familiar acquaintance with them1 before we know their real value4 #c ,the exact numbers are given in ,table ,,ii1 at the end of the book4 ,,lesson ,,iv4 ,,rotation ,,of ,,the ,,sun1 ,,the ,,earth1 ,,and ,,the ,,rest ,,of ,,the ,,planets ,,on ,,their ,,axes4--,,day ,,and ,,night4--,,inclination ,,of ,,the ,,earth',s ,,axis4--,,seasons4 #bj4 ,besides the progressive motion of the ,planets1 of which we have spoken in the last ,lesson1 they have yet a peculiar motion like a wheel turning on its ,axle-tree4 ,this motion is called the rotation of the ,planets on their ,axes2 because each of them seems to move round a straight line passing through its centre2 like a ball turning round a piece of wire run through the middle of it4--,moreover it is customary to call such a straight line imagined to be drawn through the centre of a ,planet--the ,axis of that ,planet4 ,the double motion of the ,planets1--progressive and rotary1--is perhaps one of the most difficult things for young pupils properly to understand1 without some popular illustration4 ,if the teacher1 therefore1 has no orrery to show this motion to his pupils1 he may compare it to a screw which is turned round whilst it suffers at the same time a progressive motion2 or perhaps with more propriety to a spinning-top1 which is continually turning on its ,axis1 while at the same time it describes large circles4#d #ba4 ,if you have well understood what has just been said1 you will be able to comprehend1 that our ,earth1 while it is performing its great journey round the ,sun in ,three ,hundred and ,sixtyfive days1 is1 at the same time1 every ,twentyfour hours turning on its ,axis4 ,this rotary motion of our ,earth on its ,axis is the cause of the successive changes of day and night2 that portion of the ,earth which is turned toward the ,sun having always day1 when the other1 which is turned away from him1 has night4 ,this is again a wise dispensation of ,god's providence4 ,for if the ,earth would always keep the same relative position to the ,sun1 then that portion of it1 which would then be turned toward the ,sun1 would have continual day1 whilst the other1 which would then be turned away from him1 would be enveloped in perpetual darkness4 ,but as it is now arranged by the ,earth's rotation on its ,axis1 most every portion of its surface must at least once every ,twentyfour hours be turned toward the ,sun and receive from him light and heat4 ,without this1 one great half of our ,earth would have a perpetual winter1 destructive to plants and animals1 while an everlasting summer would scorch the other half and render it equally unfit for the support of man4 ,the following ,diagram1 ,plate ,,ix1 may serve to give you an idea of the ,earth's rotation round its ,axis1 and the alternate succession of ,day and ,night1 resulting from it4 ,when the ,earth is situated as represented in the ,diagram1 then that portion of it1 which is marked ,a1 will have ,day1 because it is turned toward the ,sun2 and the portion marked ,b1 will have ,night4 ,but in the course of the next ,twelve hours the order will be reversed4 ,the portion which is marked ,b1 will be turned toward the ,sun and have day1 whilst the portion ,a will be turned from him1 and have night4 #bb4 ,the rotation of the ,earth on its ,axis is also the cause of the ,rising and ,setting of the ,sun4 ,for no portion of our ,earth is at once turned toward or from the ,sun2 but moves toward or from it by degrees 7as you may see by slowly turning a ball near the flame of a candle74 ,this gradual motion of each portion of the ,earth's surface toward or from the ,sun1 makes the ,sun himself appear to us as rising and going down2 while1 in fact1 we ourselves are turning towards1 or receding from him4 ,this is a kind of deception similar to that which you experience when slowly gliding down a river2 when the objects on shore have the appearance of receding from you1 while in fact1 it is you1 yourself1 who are travelling away from them4 ,illustration3 ,no4 ,,ix4 ,the gradual rise and setting of the ,sun is another excellent provision of nature4 ,were we from the darkness of night at once exposed to the luminous rays of the ,sun1 it would dazzle our eyes and render them unfit to distinguish a single object4--,it is only by a gradual transition from darkness to light that we are able to accustom our eyes to the brilliancy of noon4 #bc4 ,there is another peculiarity in the situation of our ,earth with regard to the ,sun1 which you have not yet learned4 ,the ,earth's ,axis is not even 7parallel7 with that of the ,sun2 but is somewhat inclined towards it1 as represented in the last ,diagram4 ,to this is owing the ,change of the ,seasons4 ,for on account of the inclination of the ,earth's ,axis1 the ,sun's rays fall1 sometimes nearly perpendicular upon us1 while at other times they are striking us more obliquely#e4 ,this is the principal cause of those changes of temperature which we are in the habit of distinguishing by the names1 ,spring1 ,summer1 ,autumn and ,winter4 ,in winter the ,sun's rays strike us most obliquely2 it is therefore the coldest season of the year4 ,in summer they are most perpendicular2--,summer therefore is the hottest season4 ,spring and autumn are standing in the middle between these two4 ,from spring till mid-summer the ,sun's rays are striking us more and more perpendicularly2 from mid-summer till winter more and more obliquely4 ,a similar change of temperature is felt every day from ,sun-rise 7when the ,sun-beams are most oblique7 till noon1 7when they are most perpendicular72 and from noon again towards evening or ,sun-set1 when they are again oblique4 #bd4 ,it has been mentioned 7,lesson ,,iv1 #bj71 that each ,planet in our ,solar ,system is regularly turning on its ,axis4 ,but all of them do not perform this rotation with equal velocity4 ,the ,planets which are farther from the ,sun are turning quicker than those which are near him4 ,jupiter1 for instance1 turns on its ,axis twice as fast as our ,earth4 ,the nights in ,jupiter1 therefore1 do not last half as long as ours4 ,this is1 in some degree1 necessary4 ,for in proportion as a planet is further from the ,sun1 it receives less light and heat1 which deficiency is1 in part1 made up by a more frequent exposition to his rays4 #be4 ,the ,sun himself is also known to turn regularly on his ,axis1 and to complete one whole rotation in about ,twentysix of our days4 ,this we have been able to perceive from the spots which have been discovered on its surface1 and which gradually move toward and disappear on one side1 when in a short time after they appear again on the other4 #bf4 ,the ,moon1 and the ,satellites of the other ,planets have no rotary motion2 but have always the same side turned towards their ,planets4 ,thus the moon keeps constantly the same side turned towards the ,earth2 but her monthly motion round the ,earth 7,lesson ,,iii1 #ag7 is equal to a rotation on her axis2 because by this means every part of her is1 at least1 once every ,twentyseven days turned toward the ,sun2 as you may see from the ,moon's phases1 represented on plate ,,vii4 ,a day in the ,moon1 therefore1 is equal to ,twentyseven of our days2 because the ,moon moves in ,twentyseven of our days round the ,earth1 which is equal to turning once on her axis4 ,,recapitulation ,,of ,,lesson ,,iv4 ,,questions4 #bj4 ,is the progressive motion of the ,planets round the ,sun the only one which they are performing8 ,what other motion have they besides this8 ,what is this motion called8 ,why is it called so8 ,what do you call a straight line imagined to be drawn through the centre of a ,planet8 ,to what may the double motion of the ,planets' progression and rotary be compared8 #ba4 ,what time does the ,earth need to turn once on its axis8 ,how many times does the ,earth turn on its axis during its whole journey round the ,sun8#f ,what is this rotary motion of our ,earth the cause of8 ,which portion of the ,earth has day8 ,which night8 ,what would be the case1 if the ,earth was always to keep the same relative position with regard to the ,sun8 ,what is the advantage derived from the rotation of the ,earth on its ,axis4 ,would the ,earth be habitable without it or not8 ,the pupil ought now to explain plate ,,ix4 #bb4 ,what is the rotation of the ,earth on its axis further the cause of8 ,what does the gradual motion of each portion of our ,earth towards the ,sun produce8 ,what would be the case1 if from the darkness of night we were at once exposed to the luminous rays of the ,sun8 ,could our eyes endure the brightness of noon without a gradual transition from darkness to light8 #bc4 ,what other peculiarity is there in the situation of the ,earth with regard to the ,sun8 ,what is this the cause of8 ,do the rays of the ,sun strike us at all times equally perpendicular or obliquely8 ,what changes of temperature are thereby created8 ,how do the rays of the ,sun strike us in winter8 ,what season1 therefore1 is it8 ,how do the rays of the ,sun strike us in summer8 ,what season1 therefore1 is summer with regard to temperature8 ,how are the rays of the ,sun striking us from spring till mid-summer8 ,how1 from mid-summer till winter8 ,what similar change of temperature do we experience every day from ,sun-rise till noon1 and from noon till evening or ,sun-set8 #bd4 ,do all ,planets turn on their axes with equal velocities8 ,which ,planets turn quicker1 those which are nearer or those which are further from the ,sun8 ,give an instance4 ,how long are ,jupiter's nights in comparison to our's8 ,why is this1 in some degree1 necessary8 #be4 ,is the ,sun himself also known to turn on its axis like the ,planets8 ,how many days does he need for one complete rotation8 ,by what means have we been able to observe this motion8 #bf4 ,have the ,moon and the ,satellites of the other ,planets also a rotary motion8 ,in what position does the ,moon remain with regard to the ,earth8 ,but what is her monthly revolution round the ,earth equal to8 ,why8 ,what is a day in the ,moon equal to8 ,why8 ,,footnotes3 #d ,the propriety of this comparison becomes still more evident1 when we reflect that the ,axis of the top is generally somewhat inclined to the plane4 #e ,if the terms perpendicular and oblique1 should not be perfectly understood by the pupils1 it will be easy for the teacher to explain their meaning4 #f ,if the ,earth requires #cfe days to travel round the ,sun2 and each day has twentyfour hours2 then the ,earth will1 during the whole of this time1 turn ,three ,hundred and ,sixtyfive times on its axis4 ,,lesson ,v4 ,,of ,,the ,,appearance ,,and ,,peculiarities ,,of ,,the ,,moon ,,and ,,some ,,of ,,the ,,planets ,,when ,,viewed ,,through ,a ,,telescope4 #bg4 ,next to the ,sun there is no heavenly body so interesting to us as the ,moon4 ,when viewed through a good ,telescope#g she has nearly the same appearance as in ,figure ,i1 ,plate ,x4 ,the bright parts are supposed to be lofty mountains and tracts of land2 7which is evident also from the shadow which they cast7 and the dark spots are supposed to be valleys and caverns4 ,many of the mountains of the ,moon are higher than the largest mountains on the ,earth4 ,some of them are volcanos1 and their eruptions have been distinctly observed by many distinguished ,philosophers4 ,some of the caverns are ascertained to have a depth of many miles and a width of almost ,three miles4--,no water has as yet been discovered in the ,moon4 ,hence if she is inhabited1 as we have reason to believe1 her inhabitants must be very differently constructed from ourselves4 #bh4 ,among the ,planets ,venus is by far the most beautiful in appearance4 ,she is known also by the name of the ,morning and ,evening ,star4 ,her light is so bright that she is often seen at ,noon4 ,when viewed through a good telescope she exhibits phases similar to those of the ,moon 7,lesson ,,iii1 #ag71 which proves her spherical form 7,lesson ,i1 #c74 ,the mountains in ,venus have been calculated to be at least ,six times as high as those on our ,earth4 ,her ,atmosphere is only half as dense as ours4 #bi4 ,mars appears in many respects similar to our ,earth4 ,his light is red and changeable2 his surface exhibits black changeable spots 7see ,figure ,,ii1 ,plate ,x74 ,some philosophers pretend to have noticed a region of ice on his poles4 ,his atmosphere is twice as dense as ours4 ,illustration3 ,no4 ,x4 #cj4 ,jupiter1 viewed through a telescope1 exhibits a surface covered with stripes4 ,these are supposed to be clouds4 ,a representation of them is given in ,fig4 ,,iii1 ,plate ,x4 ,his light is very white and subject to but little variation4 ,his atmosphere is nearly ,twentyseven times denser 7thicker7 than ours4 #ca4 ,very remarkable1 as we have already observed1 is the ,planet ,saturn1 on account of its luminous ring4 ,viewed through a telescope it has the appearance1 represented in ,figure ,,iv4 ,it is highly probable that to the inhabitants of that ,planet1 this ring has an entirely different appearance from what it has to us4 ,it appears to be a solid opaque mass1 and is probably inhabited like the ,planet1 which it constantly accompanies on its journey round the ,sun4 ,saturn's atmosphere is nearly ,ninety times denser than that of our ,earth4 ,no mountains have as yet been discovered on its surface4 99 99 99 99 99 ,herschel is too remote1 for us to know much about its surface4 ,its atmosphere is supposed to be ,three ,hundred and ,sixty-one times thicker than ours4 ,mercury1 being the nearest ,planet to the ,sun1 has a very bright light2 but is only seen early before ,sun-rise1 and immediately after ,sun-set4 ,it exhibits ,phases like the ,moon4 ,,recapitulation ,,of ,,lesson ,v4 ,,questions4 #bg4 ,what do you know about the ,moon's surface8 ,what1 about its mountains1 volcanos and caverns8 ,have any great waters been discovered in it8 #bh4 ,what do you know about the ,planet ,venus8 ,by what other name is she known8 ,what does she exhibit1 when viewed through a telescope8 ,what do you know about her mountains8 ,what1 about her atmosphere8 #bi4 ,what do you know about the ,planet ,mars8 ,what1 about his light1 surface and atmosphere8 #cj4 ,what surface does ,jupiter exhibit when viewed through a telescope8 ,of what color is the light of ,jupiter8 ,what do you know about his atmosphere8 #ca4 ,what do you know about the ,planet ,saturn8 ,what does the ring of ,saturn appear to be8 ,what do you know about the atmosphere of this ,planet8 ,,footnotes3 #g ,this is an instrument through which we can see things much clearer and larger than we could with the naked eye4 ,,lesson ,,vi4 ,,description ,,of ,,the ,,earth',s ,,surface4--,,division ,,of ,,it ,,into ,,zones4--,,torrid1 ,,temperate ,,and ,,arctic ,,zones4--,,the ,,five ,,great ,,continents4--,,relative ,,dimensions ,,of ,,america1 ,,europe1 ,,asia1 ,,africa ,,and ,,australia4 #cb4 ,having learned the relation of our ,earth to the ,sun and the ,planets1 it will be well to acquaint ourselves with the principal objects on its surfaces4--,what the ,interior of our ,earth consists of1 we have as yet no idea1 because we have not yet been able to penetrate deeper than a few hundred feet2 and this is1 in proportion to the ,earth's ,diameter1 little more than nothing4 ,but as regards her surface1 we know that it consists partly of land and partly of water4 ,little more than one fourth of the ,earth's surface is covered with land2 all the rest is water4--,the great lands are called ,continents2 the great waters are called ,oceans4 ,smaller portions of land surrounded on all sides by water1 are called ,islands4 ,smaller bodies of water surrounded by land are called ,lakes4 #cc4 ,the land on our ,earth is divided into ,five ,continents3 ,america1 ,europe1 ,asia1 ,africa and ,australia4--,these1 however1 are not all of the same extent4 ,europe is the smallest of them4 ,america and ,asia are the greatest4 ,the adjoining ,plate ,no4 ,,xi1 will give you an idea of the proportion of land and water on our ,earth1 and of the relative extent of the ,five ,continents4 ,fig4 ,i represents the surface of the ,earth divided into land and water4 ,were all land on our ,earth put together in a circle1 and the water placed round it1 then the land would only fill the inner circle1 the water occupying the surrounding ring1 a space nearly four times as large as the circle4 ,fig4 ,,ii1 ,,iii1 ,,iv1 ,v and ,,vi represent the comparative surfaces of ,america1 ,europe1 ,asia1 ,africa and ,australia4 ,fig4 ,,vii represents the comparative surface of the ,moon4 ,upon close inspection of these figures you will perceive2 #a4 ,that the extent of ,america and ,asia are nearly equal2 but that each of these ,continents is several times larger than either ,europe or ,australia4 #b4 ,that the next greatest portion of our ,globe is ,africa1 which is more than three times larger than ,europe4 #c4 ,that ,europe is the smallest ,continent of our globe4 #d4 ,that the whole surface of the ,moon would not be more than enough to cover either ,america or ,asia4 ,illustration3 ,no4 ,,xi4 ,fig4 #a4 ,,the ,,ocean ,,the ,,land ,fig4 #b4 ,,europe ,fig4 #c4 ,,asia ,fig4 #d4 ,,africa ,fig4 #e4 ,,america ,fig4 #f4 ,,australia ,fig #g4 ,,the ,,moon',s ,,surface ,geographical ,miles4 ,illustration3 ,no4 ,,xii4 ,fig4 #a4 ,,the ,,whole ,,torrid ,,zone ,comparative ,extent of the ,,two ,,temperate ,,zones ,comparative ,,extent of the ,,two ,,arctic ,,zones ,fig4 #b4 ,comparative ,extent of one of the ,,whole ,,torrid ,,zone ,fig4 #c4 ,comparative ,extent of one of the ,,two ,,temperate ,,zones ,fig4 #d4 ,,one of the ,,arctic ,,zones ,fig4 #e4 ,comparative ,extent of the ,,whole ,,land on our ,,globe ,illustration3 ,no4 ,,xiii4 ,illustration3 ,no4 ,,xiv4 ,square contents of the ,two ,,temperate ,,zones4 ,square contents of the ,,whole ,,torrid ,,zone4 ,square contents of the ,two ,,arctic ,,zones4 ,the whole surface of the five ,,great ,,continents on our ,,globe ,compared to one of the two ,,temperate ,,zones4 #cd4 ,the ,earth's surface is not throughout equally illumined or heated by the ,sun2 because the ,sun's rays strike some portions of the ,earth more perpendicular than others4 ,our ,earth1 therefore1 is divided into ,climates or ,zones1 which you will understand better from ,plate ,,xii4 ,you will see from it that the ,sun's rays are perpendicular to the central part of the ,earth's surface2 but that toward the extremities of the ,earth's ,diameter these rays strike us more and more obliquely4 ,the greatest heat1 therefore1 must be felt by the people living between the two circles ,,ef and ,,ik4 ,the circle ,,gh1 which is exposed to the perpendicular rays1 is termed the ,equator2 and the two circles ,,ef and ,,ik1 which are at equal distance from the ,equator1 are called ,tropic ,circles4 ,the whole surface included by these two circles is called the torrid ,zone4 ,the space between either of the circles ,,cd and ,,ef1 or ,,ik and ,,lm1 is called a temperate ,zone2 because the ,sun's rays striking these portions neither perpendicular nor very obliquely1 their inhabitants suffer neither great heat nor cold4 ,in one of these ,zones are situated the ,united ,states of ,america and the greater portion of ,europe4 ,beyond them1 toward the extremities of the ,diameter ,,ab1 are the two icy or arctic zones4 ,the ,sun's rays strike them very obliquely2 which is the cause of their being almost continually covered with ice or snow4 ,the two circles1 ,,cd and ,,lm1 are called ,polar circles2 and the two extremities1 ,a and ,b1 of the ,earth's ,diameter1 situated in those regions1 are called the ,poles4 ,a is called the ,north-,pole and ,b the ,south-,pole of the ,earth4 #ce4 ,the different zones of which we have just spoken1 are not equal to one another4 ,plate ,,xiii1 will show their relative extent4 ,fig4 ,i represents the surface of the ,earth divided proportionally into its three zones3 the torrid1 the temperate and the arctic4 ,the inner circle represents both the arctic zones2 the yellow ring b1 which surrounds it1 represents the united extent of the two temperate zones2 and the outmost red ring1 the whole of the two torrid zones4 ,fig4 ,,ii represents separately the whole torrid zone2--,fig4 ,,iii one of the temperate zones2--,fig4 ,,iv one of the arctic zones2 and ,fig4 ,v the whole extent of land on our globe4 ,the next ,plate1 ,no4 ,,xiv1 represents the comparative surfaces of these zones1 drawn separately in form of squares2 and the last figure on that ,plate1 shows the extent of the five continents1 compared to one of the temperate zones4 ,illustration3 ,no4 ,,xv4 ,fig4 #a4 ,fig4 #b4 ,fig4 #c4 ,fig4 #d4 ,fig4 #e4 ,fig4 #f4 ,you will observe from a close inspection of these figures1 that the whole extent of land on our globe is nearly equal to that of a temperate zone2 and that if it were possible to unite ,america1 ,europe1 ,asia1 ,africa and ,australia into one1 their united extent would not yet fill one of the temperate zones6 ,you will also perceive that the two temperate zones occupy together the greatest portion of the ,earth's surface1 and that the arctic zones occupy comparatively the smallest4 ,,recapitulation ,,of ,,lesson ,,vi4 ,,questions4 #cb4 ,do we know anything about the ,interior of our ,earth8 ,why not8 ,what does the surface of our ,earth consist of8 ,what proportion does the land bear to the water8 ,what are the great lands called8 ,what1 the great waters8 ,what are smaller portions of land1 surrounded by water1 called8 ,what1 small portions of water1 surrounded by land8 #cc4 ,into how many continents is all the land of our ,globe divided8 ,what are they8 ,are all the continents of our globe of the same extent8 ,which is the smallest of them8 ,which are the largest8 ,explain ,plate1 ,no4 ,,xi4 ,what proportion does the extent of ,america bear to that of ,asia8 ,what relation do these continents bear to ,europe or ,australia8 ,what is the next greatest portion on our globe8 ,which continent is the smallest8 ,what relation does the surface of the ,moon bear to ,america or ,asia8 #cd4 ,is the whole ,earth equally illumined or heated by the ,sun8 ,why not8 ,what is1 therefore1 the surface of our ,earth divided into8 ,upon what portion of our ,earth do the ,sun's rays fall perpendicular8 ,what portion do they strike more obliquely8 ,what people1 therefore1 will experience the greatest heat8 ,the pupil ought now to explain ,plate ,,xii4 ,the elder pupils ought to draw a sphere with the ,equator1 the tropic and arctic circles4 ,they ought also to draw the ,diameter of the ,earth1 and indicate the ,north and ,south ,pole4 #ce4 ,if you compare the whole extent of land on our globe to the ,contents of one of the temperate zones1 what proportion do you find them to bear to each other8 ,if it were possible to unite the five great continents1 ,america1 ,europe1 ,asia1 ,africa and ,australia1 what zone would they nearly fill8 ,what two zones occupy the largest portion of the ,earth's surface8 ,what two1 the smallest8 ,,appendix ,,containing ,,the ,,comparative ,,population ,,of ,,the ,,different ,,quarters ,,of ,,our ,,globe4 ,the numbers are given in ,table ,,iii4 #cf4 ,the ,five principal parts of our globe1 ,america1 ,europe1 ,asia1 ,africa and ,australia are not equally thickly settled4 ,europe and ,asia have1 in proportion to their extent1 the greatest population2 ,america and ,australia the least4--,the following ,plate1 ,no4 ,,xv1 shows the comparative population of these continents4 ,fig4 ,i represents the whole surface of land on our globe1 inhabited by nearly ,one ,thousand ,millions 7,one ,billion7 human beings4 ,if these were to live throughout as close together as in ,europe1 then they would only occupy a surface of land as large in proportion1 as the inner circle marked a4 ,but the two rings1 b and c1 occupy each as much surface as the circle a2 hence there is yet room for twice as many human beings2 before each quarter of the world is as thickly settled as ,europe4 ,fig4 ,,ii represents ,asia and its population4 ,if this quarter were settled as thickly as ,europe is1 then its inhabitants would only fill the inner circle marked b2 the ring a1 therefore1 is still left for settlement4 ,fig4 ,,iii exhibits the population of ,africa4 ,if the inhabitants of this continent lived as close together as those of ,europe1 they would only fill the inner circle1 marked c1 and the surrounding ring might yet be inhabited4 ,fig4 ,,iv shows the comparative population of ,america4 ,its inhabitants1 crowded together as the inhabitants of ,europe1 would only occupy the small circle e2 the whole broad ring f1 therefore1 is still left for settlement66 ,fig4 ,v represents ,australia4 ,its inhabitants1 settled as in ,europe1 would only fill the circle a4 ,fig4 ,,vi represents the population of ,europe filling the whole of that ,quarter4 ,the whole of these ,six figures may represent to the pupil the comparative extents of the five great continents of our globe2 but the inner circles of these figures1 and the whole of the sixth figure1 show their comparative populations4 ,from a close inspection of this plate the pupil may learn3 #a4 ,that the population of ,asia is yet greater than that of all the rest of the world4 7,the circle b in figure ,,ii being yet larger than the inner circles of all the other figures1 and figure ,,vi taken together47 #b4 ,that the population of ,europe is as yet larger than that of ,america1 ,africa and ,australia1 taken together4 #c4 ,that the population of ,africa is larger than the joint populations of ,america and ,australia4 #d4 ,that ,america if once settled as ,europe is1 will have more than ,six times her population4 ,the teacher1 if he think proper to ask the pupils some questions in reference to the ,appendix1 will find no difficulty in adapting them to the capacity of his pupils4 ,,table ,i4 ,showing the ,diameter1 ,surface1 and ,cubic ,contents of the ,sun and the ,planets4 ,diameter in ,surface in ,cubic ,contents ,geographical ,geographical in ,geographical ,names4 ,miles4 ,square ,miles4 ,cubic ,miles4 ,,sun1 #aid1jjj #aah1jic1jjj1jjj #c1hbe1ijc1bec1igj1jjj ,mercury1 #fjh #a1afa1cad #aag1fei1jii ,venus1 #afgh #h1hdd1jfc #b1dgc1dfi1gdc ,earth1 #agai #i1bhb1jff #b1fei1aei1jfa ,mars1 #ajjf #c1agh1hje #ecb1iif1cag ,vesta1 #gd #ae1jjj #b1aba1cdg ,juno1 #cji #bhb1fij #b1cee1gej ,ceres1 #ceb #chi1ahb #bb1hcb1jcd ,pallas1 #dfe #fej1bff #eb1hhf1dgb ,jupiter1 #aieff #a1bjb1bhj1djf #bc1ecc1adc1eig1fca ,saturn1 #agbfc #icf1ecj1fbj #b1geg1edg1idf1gge ,herschel1 #gefd #agc1fif1iaa #a1cei1bbg1dch1heh ,moon1 #dhj #gbc1fhf #ea1efa1egh ,,table ,,ii4 ,showing the exact ,duration of the ,revolutions of the different ,planets round the ,sun4 ,duration of the ,planets4 ,years4 ,days4 ,hours4 ,min4 ,sec4 ,moon's revolution round the ,earth4 ,mercury1 -- #hg #bc #ae #dd #bg days1 #g hours1 #dc ,venus1 -- #bbd #af #di #aj minutes1 and #ab ,earth1 #a -- #f #i #h seconds4 ,mars1 #a #cba #bb #ah #ca ,vesta1 #c #bbe -- -- -- ,juno1 #d #aca #aj #cj -- ,ceres1 #d #bbj #ac #d -- ,pallas1 #d #bba #ae #ce -- ,jupiter1 #aa #cad #bj #ci -- ,saturn1 #bi #aff #b -- -- ,herschel1 #hc #bff #i -- -- ,,table ,,iii4 ,showing the ,extent and ,population of the five great ,continents4 ,names of the ,continents4 ,extent in ,sq4 ,miles4 ,population4 ,america1 #ad1hfh1jjj #dj1jjj1jjj ,europe1 #c1bib1jjj #aih1jjj1jjj ,asia1 #ae1jjj1jjj #ejj1jjj1jjj ,africa1 #aa1bfg1ijj #aej1jjj1jjj ,australia1 #c1hbc1bjj #a1ejj1jjj ,the ,united ,states1 #a1gha1ibf #ac1jjj1jjj ,,popular ,,lessons ,,in ,,astronomy1 ,,on ,a ,,new ,,plan2 ,,in ,,which ,,some ,,of ,,the ,,leading ,,principles ,,of ,,the ,,science ,,are ,,illustrated ,,by ,,actual ,,comparisons1 ,,independent ,,of ,,the ,,use ,,of ,,numbers4 ,,by ,,francis ,j4 ,,grund1 ,,author ,,of 8,,an ,,elementary ,,treatise ,,on ,,plane ,,and ,,solid ,,geometry10 8,,elements ,,of ,,natural ,,philosophy ,,and ,,chemistry10 c4 c4 ,,boston3 ,,carter1 ,,hendee1 ,,and ,,co4 #ahcc4