,,the ,,moon ---------------------------------------- -------------------------------- ,illustration3 ,,copernicus ,,and ,,the ,,carpathian ,,mountains4 ---------------------------------------- -------------------------------- ,,the ,,moon ,a ,,popular ,,treatise ,by ,,garrett ,p4 ,,serviss ,illustration ,d4 ,,appleton ,,and ,,company ,,new ,,york #aijg ---------------------------------------- -------------------------------- ,,copyright1 #aijg1 ,,by ,d4 ,,appleton ,,and ,,company ,published ,october1 #aijg ---------------------------------------- -------------------------------- ,,preface ,,the reader familiar with astronomical literature will doubtless remark a certain resemblance between the plan on which this book is written and that of ,fontenelle's 8,conversations on the ,plurality of ,worlds10 a ,french classic of the eighteenth century4 ,the author freely acknowledges that it was the recollection of the pleasure which the reading of ,fontenelle's book gave him1 years ago1 that led to the adoption of a somewhat similar plan for this description of the moon4 ,but1 except that in both cases the conversational method is employed1 no great likeness will be found between what is here presented and the work of the witty ,frenchman4 ,having been invited by the ,messrs4 ,appleton ,co4 to prepare a small volume1 to be based on a series of lunar photographs representing the moon as it appears on successive evenings during an entire lunation1 the author felt that the work should be made as entertaining as possible4 ,he has1 therefore1 avoided technicalities1 while endeavoring to present all the most essential facts known about our satellite4 ,what he has written is intended for the general reader1 who desires to learn the results of the great advances in astronomy without being too much troubled with the scientific methods by whose aid those results have been reached4 ,this is the first time1 as far as the author is aware1 that a series of lunar photographs1 showing our satellite in its varying aspects from ,new to ,old ,moon1 has been presented in a book1 accompanied with a description of the mountains1 plains1 volcanoes1 and other formations shown in each successive photograph4 ,the reader is enabled to place himself1 as it were1 in an observatory of the first rank1 provided with the most powerful apparatus of the astronomer1 and1 during an entire month1 view the moon in her changing phases4 ,the photographs here reproduced were made at the ,yerkes ,observatory1 and the most grateful acknowledgments are tendered to ,prof4 ,edwin ,b4 ,frost1 its director1 for generously consenting to their use for this purpose4 ,he could only have been induced to do so by his desire to see the fruits of the admirable work accomplished by his associates enjoyed by an ever-widening circle4 ,the series of photographs representing the moon on successive evenings were taken with the #ab-;inch telescope of the ,yerkes ,observatory by ,mr4 ,james ,wallace1 who employed a color filter that he constructed specially for this telescope1 which possesses a visual and not a photographic objective4 ,the larger scale photographs1 representing certain selected regions on the moon1 were taken by ,mr4 ,ritchey1 now of the ,carnegie ,solar ,observatory at ,mount ,wilson1 ,california1 with the great #dj-;inch telescope of the ,yerkes ,observatory4 ,it is unnecessary to speak of the extraordinary quality of these photographs1 which have been admired by astronomers in all lands4 ,it should1 perhaps1 be added that while the director of the ,yerkes ,observatory has shown confidence in the author by intrusting to him the use of these photographs1 yet1 neither ,professor ,frost1 nor ,messrs4 ,wallace and ,ritchey are in any way responsible for the statements made in this book4 ,the author has taken pains to be accurate1 but if any errors of fact or opinion have crept in1 he alone must be blamed for them4 ,,garrett ,p4 ,,serviss4 ,,ch,,teau ,d',,arceau1 ,c,,te ,d',,or1 ,,france1 ,june1 #aijg4 ---------------------------------------- -------------------------------- ,,contents ,,page ,,introduction #c ,i4 --,,new ,,moon ,,to ,,first ,,quarter #dg ,,ii4 --,,first ,,quarter ,,to ,,full ,,moon #hc ,,iii4 --,,full ,,moon ,,to ,,old ,,moon #aca ,,iv4 --,,great ,,scenes ,,on ,,the ,,moon #aha ,,appendix #bci ,,index #bdc ---------------------------------------- -------------------------------- ,,list ,,of ,,illustrations ,,full-,,page ,,illustrations ,copernicus and the ,carpathian ,mountains ,frontispiece ,,photographs ,,of ,,the ,,moon ,,showing ,,phases ,,of ,,change ,,page ,no4 #a1 ,february #ai1 #aijd2 ,moon's ,age #c4he ,days #ej ,no4 #b1 ,september #bd1 #aijc2 ,moon's ,age #c4hg ,days #ef ,no4 #c1 ,july #bi1 #aijc2 ,moon's ,age #e4ed ,days #ff ,no4 #d1 ,november #bd1 #aijc2 ,moon's ,age #e4gd ,days #gb ,no4 #e1 ,july #a1 #aijc2 ,moon's ,age #f4bd ,days #gd ,no4 #f1 ,november #bf1 #aijc2 ,moon's ,age #g4ge ,days #gh ,no4 #g1 ,july #b1 #aijc2 ,moon's ,age #g4bd ,days #ij ,no4 #h1 ,august #ca1 #aijc2 ,moon's ,age #i4bb ,days #id ,no4 #i1 ,august #b1 #aijc2 ,moon's ,age #h4ig ,days #ajb ,no4 #aj1 ,november #cj1 #aijc2 ,moon's ,age #aa4gh ,days #ajf ,no4 #aa1 ,december #a1 #aijc2 ,moon's ,age #ab4ih ,days #aab ,no4 #ab1 ,september #d1 #aijc2 ,moon's ,age #ac4bg ,days #aah ,no4 #ac1 ,september #e1 #aijc2 ,moon's ,age #ad4dj ,days #abb ,no4 #ad1 ,august #bf1 #aijd2 ,moon's ,age #ae4fe ,days #acb ,no4 #ae1 ,august #bh1 #aijd2 ,moon's ,age #ag4da ,days #acd ,no4 #af1 ,august #bi1 #aijd2 ,moon's ,age #ah4fb ,days #ach ,no4 #ag1 ,october #aj1 #aijc2 ,moon's ,age #bj4jf ,days #adb ,no4 #ah1 ,september #bi1 #aijd2 ,moon's ,age #bj4ej ,days #add ,no4 #ai1 ,august #af1 #aijc2 ,moon's ,age #bc4ha ,days #aej ,no4 #bj1 ,august #ag1 #aijc2 ,moon's ,age #bd4hd ,days #aeh ,no4 #ba1 ,august #ai1 #aijc2 ,moon's ,age #bf4hi ,days #afh ,,photographs ,,of ,,the ,,moon ,,showing ,,significant ,,features ,,page ,bullialdus and the ,mare ,nubium #ahb ,tycho1 ,clavius1 and their ,surroundings #aib ,the ,great ,southwest on the ,moon #aih ,the ,giant ,ring ,mountain ,theophilus and its #bjf ,neighbors4 ,two ,great ,lunar 8,seas0--the ,mare ,serenitatis and #bah a ,part of the ,mare ,imbrium ,,diagrams ,,in ,,text ,,page ,phases and ,rotation of the ,moon #ad ,the ,moon's ,path with ,respect to the ,sun and the #ag ,earth ,the ,moon and the ,tides #bc ,effect of ,moon1 ,varying ,velocity in ,orbit #eh ,producing ,libration in ,longitude ,lunar ,volcano1 in ,section #he ,terrestrial ,volcano1 in ,section #he ,diagram ,showing ,why the ,winter ,moon ,runs ,high #agj ,diagram ,showing ,why ,moon ,rises ,later ,every ,night #agc ,diagram ,illustrating the ,harvest ,moon #agd ---------------------------------------- -------------------------------- ,,introduction ---------------------------------------- -------------------------------- ,,introduction ,,one serene evening1 when the full moon1 rising slowly above the tree tops1 began to spread over the landscape that peculiar radiance which1 by half revealing and half concealing1 by softening all outlines1 and by imparting a certain mystery to the most familiar objects1 fascinates at once the eye and the imagination1 ,i was walking with a friend1 a lady of charming intelligence1 in a private park adjoining an old mansion in one of the most beautiful districts of central ,new ,york4 ,for a long time we both remained silent1 admiring the scene before us1 so different in every aspect from its appearance in the glare of daylight--each occupied with the thoughts that such a spectacle suggests4 ,suddenly my friend turned to me and said3 8,tell me--for1 like so many thousand others1 ,i am virtually ignorant of these mysteries of the sky--tell me1 what is that moon8 ,what do astronomers really know about it80 8,but10 ,i replied1 8you certainly exaggerate your ignorance4 ,you must have read what so many books have told about the moon40 8,not a word10 was the reply1 8or at least1 what ,i have read has made little impression upon my mind4 ,i read few books of science2 generally they repel me4 ,but face to face with that marvelous moon1 ,i find it irresistible1 and my desire for knowledge concerning it becomes intense4 ,i remember something about eclipses1 and something about tides1 with which1 ,i believe1 the moon is concerned4 ,i recall the statement that the moon has no atmosphere1 but does possess great mountains and volcanoes4 ,yet these things are so jumbled in my memory with technical statements which failed to interest me1 that really my ignorance remains profound4 ,but ,i have heard that many surprising discoveries have been made lately concerning the moon1 and that astronomers have succeeded in taking wonderful photographs of scenes in the lunar world4 ,i have1 indeed1 seen copies of some of these photographs1 but beyond awaking curiosity by their bizarre effects of light and shadow1 they impressed me little1 for lack1 ,i suppose1 of information as to their meaning4 ,i beg you1 then1 to tell me what is really known about the world of the moon4 ,there it is2 ,i see it2 ,i experience the delightful impressions which its light produces--but1 after all1 what is it1 and what should we behold if we could go there8 ,i once read ,jules ,verne's romance of a trip to the moon1 but unfortunately his adventurers never really got there1 and ,i finished the story with a keen sense of disappointment because1 in the end1 he told so very little about the moon itself4 ,as for the professional books of the astronomers they are useless to me4 ,then1 please tell me that which1 at this moment1 with that wonderful orb actually in sight1 ,i so much desire to know40 ,it was not possible to resist an appeal so earnestly urged1 but ,i felt compelled to say3 8,since you remember so little about the fundamental facts which generations of astronomers have accumulated concerning our nearest neighbor in the sky1 ,i must1 for the sake of completeness1 and in order to put you au courant with the more captivating things that will come later1 begin at the beginning1 and the true beginning is not among the mountains of the moon1 but here on the earth4 ,we must start from our own globe--as the moon herself did40 8,what do you mean by that80 my friend asked with a tone of surprise4 8,have you not read1 somewhere1 in the last ten years1 that the moon was actually born from the earth80 8,yes1 now that you mention it1 ,i dimly recall something of the kind1 but ,i took it for an extravagant speculation of some savant who possessed more imagination than solid knowledge40 8,the savant who originally demonstrated the earthly origin of the moon10 ,i replied1 8is not one to be easily led into extravagance by his imagination4 ,it is ,prof4 ,george ,darwin1 the son of the famous author of the #8,origin of ,species4' ,i shall not mention his mathematics1 which are troublesome1 but allow me to tell you1 in a word1 that his investigations have satisfied astronomers that the earth and the moon once composed a single body4 ,how many million years ago that was we can only guess4 ,the causes of the separation which eventually occurred were the plastic condition of the original body while it was yet hot and molten1 its swift axial rotation producing an immense centrifugal force at its equator1 and the attraction of the sun raising huge tides which affected its entire mass instead of affecting only the waters of the ocean as the tides do at present4 ,at last there came a time when an enormous portion of the swiftly rotating globe was torn loose4 ,that portion included about one-eightieth of the entire mass of the earth4 ,some astronomers and geologists think that the #8wound' left in the side of the earth by this stupendous excision is yet traceable in the basin of the ,pacific ,ocean4 8,the separation being once effected1 the material that had escaped gradually assumed a globular form under the influence of the gravitation of its own particles2 and1 at the same time1 by virtue of a curious reaction of the tidal attractions of the two bodies upon each other1 the new-born globe was slowly forced away from its mother earth1 becoming1 in fact1 its satellite4 ,thus1 by a process which certainly does seem extravagantly imaginative1 but which1 nevertheless1 is approved by strict mathematical deductions from known physical facts1 the moon is believed to have had her birth40 8,surely10 said my companion1 8my imagination would never have dared to form such a picture1 even if it had been capable of so extraordinary a flight40 8,no10 ,i replied1 8nor the imagination of the most learned astronomer4 ,you perceive that in things celestial as in things terrestrial fact is far more strange than fiction4 ,we shall have occasion to refer to some of the consequences of the earthly origin of the moon later on1 but just now in order that the knowledge you seek may not be too fragmentary1 ,i must tell you some other1 more commonly known1 facts about our satellite40 8,judging by myself ,i doubt if there are many such facts commonly known40 8,perhaps you are right1 but do not judge too severely the authors of astronomical books4 ,such books are written primarily for those who wish to study1 not for those who desire to be intellectually entertained4 ,but let me get through with my preliminaries1 and then1 under the guidance of science and photography1 we shall try to visit the moon4 ,one of the first questions that naturally arise concerning the objects that we see in the heavens relates to their distance from us4 ,the average1 or mean1 distance of the moon from the earth is #bch1hdj miles4 ,for the sake of a round number we usually call it #bdj1jjj miles4 ,but the orbit1 or path1 of the moon in her monthly journey around the earth1 is so far from being a true circle that the distance is variable to the extent of #ca1jjj miles4 ,even the form of the moon's path in space is not constant4 ,owing to the varying effects of the attraction of the earth and the sun1 her elliptical orbit becomes now a little more and now a little less eccentric1 the consequence being that the moon's distance from the earth is continually changing4 ,when she is at her greatest possible distance she is #bec1jjj miles away1 but this distance at certain times1 may be reduced to only #bba1fjj miles4 ,as a result of these changes of distance the moon sometimes appears noticeably larger to our eyes than at other times4 8,this leads us next to inquire1 #8,what is the actual size of the moon8' ,when we know the distance of any body from the eye it is not difficult to determine its size4 ,the diameter of the moon is #b1afc miles4 ,the face of the full moon contains #g1cjj1jjj square miles4 ,it is a little larger than the continent of ,south ,america4 ,for a reason that we will speak of presently1 the moon always keeps the same side toward us no matter in what part of its orbit it may be4 ,consequently we always see the same features of her surface and1 except through inference1 we do not know what exists on the other side of the lunar globe4 ,of the #g1cjj1jjj square miles of surface which the moon presents to us1 about #b1ijj1jjj are occupied by those dark gray patches which you see so plainly spotting her face1 and which were once supposed to be seas4 ,the remaining #d1djj1jjj square miles consist of a very rough1 broken country1 ridged with gigantic mountains and containing hundreds of enormous craters1 and mountain-ringed valleys1 which are so vast that one hesitates to call them1 what many of them seem evidently to be1 extinct volcanoes4 ,a single explosion of a volcano of the dimensions of some of these lunar monsters would shake the whole earth to its center60 8,please stop a moment10 my friend laughingly interrupted4 8,so many merciless facts1 chasing one at the heels of another1 are as bad as the books on your science that ,i have tried to read4 ,give my imagination time to overtake you40 8,very well10 ,i said1 8then relieve your attention a little while by regarding the face of the moon4 ,do you perceive the portrait of the ,moon ,maiden there80 8,i believe ,i do1 although ,i never noticed it before4 ,it is in profile1 is it not80 8,yes1 and it occupies all the central portion of the western half of the disk4 ,take the opera glass and you will see it more clearly40 8,really1 ,i find her quite charming10 said my companion1 after gazing for a minute through the glass4 8,but what a coquette6 ,look at the magnificent jewel she wears at her throat1 and the parure of pearls that binds her hair60 8,yes10 ,i replied1 8and no terrestrial coquette ever wore gems so unpurchasable as those with which the ,moon ,maiden has decked herself4 ,that flaming jewel on her breast is a volcano1 with a crater more than fifty miles across6 ,tycho1 astronomers call it4 ,observe with the glass how broad rays shoot out from it in all directions4 ,they are among the greatest mysteries of lunar scenery4 ,and the string of brilliants in her hair consists of a chain of mountains greater than the ,alps--the lunar ,apennines4 ,they extend more than #dej miles1 and have peaks #bj1jjj feet high1 which gleam like polished facets40 8,truly10 said my companion1 smiling1 8these gigantesque facts of yours rather tend to dissipate the romantic impression that ,i had conceived of the ,moon ,maiden40 8,no doubt10 ,i replied4 8,it is only distance that lends her enchantment4 ,but we must not disregard the facts4 ,her hair1 you perceive1 is formed by some of the vast gray plains of which ,i spoke a few minutes ago4 ,she is like a face in the clouds--approach her1 or change the point of view and she disappears or dissolves into something else4 8,now1 to return to my preliminaries1 upon which ,i must insist4 ,knowing the distance and the size of the moon1 the next question relates to her motions4 ,you are aware that she travels around the earth about once every month4 ,there are two ways in which we measure the length of time that the moon takes for each revolution4 ,first1 regarding the face of the sky as a great dial1 with the stars for marks upon it1 we notice the time that elapses between two successive conjunctions of the moon with the same star4 ,in the interval she has gone completely around the earth and come back to the starting point4 ,this is called the moon's sidereal revolution1 and it occupies1 on the average1 twenty-seven days1 seven hours1 forty-three minutes1 twelve seconds4 ,every twenty-four hours the moon advances among the stars1 from west to east1 about #ac #aa4 8,but there is another1 more usual way of measuring the orbital period of the moon4 ,this way is connected with her phases1 or changes of shape1 from the sickle of the ,new ,moon to the round disk of the ,full ,moon1 and back again to the reversed sickle of the waning moon4 ,it is the time that elapses from one ,new ,moon to the next1 or from one ,full ,moon to the next which now concerns us1 and it amounts1 on the average1 to twenty-nine days1 twelve hours1 forty-four minutes4 ,this is called the moon's synodic revolution1 and it is equivalent to the ordinary lunar month4 ,it is variable to the amount of about thirteen hours4 ,the reason why the synodic revolution is more than two days longer than the sidereal revolution is because the continual advance of the earth in its orbit around the sun causes the latter to move eastward among the stars1 and before the moon's monthly phases1 which depend upon her position with regard to the sun1 can recommence1 she must overtake the sun40 8,what a hopeless task to try to remember all that60 8,at any rate1 if you cannot remember these things my conscience will be clear1 for ,i am simply doing my duty in telling you of them4 ,if you forget1 go to the books on astronomy and refresh your memory4 ,but do not persuade yourself that the preliminaries are now finished4 ,you are going to think that my story of the moon resembles ,walter ,scott's novels in the length of its introduction2 but if1 in the end1 ,i can interest you half as much as he finally interests his readers ,i shall thank the stars for my good fortune4 8,the next thing that ,i must try to explain10 ,i continued1 8is the cause of the moon's phases1 or her continual changes of form4 ,you know that the ,new ,moon is shaped like a thin crescent1 and always appears in the west immediately after sundown1 with the convex side facing the setting sun4 ,the moon at ,first ,quarter is a half circle and is visible in the southern part of the sky just after sunset4 ,the ,full ,moon1 which we have at present1 is a complete round disk1 and is always seen directly opposite to the place of the sun1 so that she rises when the sun sets4 ,the moon at last quarter is again a half circle1 and appears on the meridian in the south at sunrise4 ,the waning moon is like the new moon1 crescent-shaped1 but the convexity of the bow faces the rising sun1 and she is visible only in the morning sky just as dawn begins4 ,to explain the reasons for these changes of shape1 which the moon regularly undergoes every month1 ,i must ask you to go indoors and examine a little diagram which ,i have made40 8,oh60 said my companion1 8it is too bad to abandon this charming spectacle1 illuminated by rays so fascinating1 for the sake of looking at mathematical lines drawn on paper6 ,but ,i suppose that this is one of the sacrifices demanded by your inexorable science1 and must be made40 8,yes10 ,i said1 8but if science sometimes demands sacrifices1 at least she always rewards them most generously40 ,when we had returned to the house ,i placed upon the drawing-room table this diagram4 ,illustration3 ,phases and ,rotation of the ,moon4 ,as ,i spread it out1 my companion1 after a regretful glance through the open door at the silvery lawn1 on which the moon1 having cleared the obstructing branches of the bordering trees1 was now pouring down the full splendor of her rays1 put her elbows on the table to follow my explanation4 8,the globe1 half bright and half black1 in the center10 ,i said1 8represents the earth4 ,the large circle surrounding the earth we will call the moon's orbit1 which she traverses once every month4 ,the smaller globe1 also half white and half black1 shown in four successive positions in the orbit1 is the moon4 ,suppose the sun to be away off here on the left4 ,it illuminates the earth and the moon only on the side turned toward it4 ,the opposite side of both is buried in night4 ,now1 let us begin with the moon at the point ,a4 ,she is then between the earth and the sun1 the bright side being necessarily toward the sun and the dark side toward the earth4 ,in that position we do not see the moon at all from the earth1 unless she happens to come so exactly in a line with the sun as to cover the latter1 in which event we have an eclipse of the sun4 ,now1 suppose the moon to move in her orbit toward ,b4 ,in a little more than seven days she will arrive at ,b4 ,in the meantime1 while moving away from the position of the sun1 she begins to present a part of her illuminated hemisphere toward the earth4 ,this part appears in the form of a sickle1 or crescent1 which grows gradually broader1 until1 at ,b1 it has grown to a half circle4 ,in other words1 when the moon is in the position ,b we on the earth see one half of her illuminated surface4 ,this phase is called ,first ,quarter4 ,the narrow crescent1 which appears as soon as the moon begins to move from ,a toward ,b1 is the ,new ,moon4 ,as the moon continues on from ,b toward ,c1 more and more of her illuminated half is visible from the earth1 and when she arrives at ,c1 just opposite to the position of the sun1 she becomes a ,full ,moon4 ,we then see1 as occurs to-night1 the whole of that face of the moon which is presented sunward4 ,the upper half of the diagram shows how the moon moves from the position of ,full ,moon back again to ,new ,moon1 or conjunction with the sun4 ,during this latter part of her course the moon rises later and later every night1 until1 when she assumes the form of a waning crescent1 she is visible only in the morning sky just before sunrise4#a 8,now1 there is another interesting thing shown by this diagram10 ,i continued--but my companion1 who had followed my explanations thus far with flattering attention1 here suddenly ran to the door exclaiming3 8,for mercy's sake1 what is happening to the moon80 ,footnote #a3 ,illustration3 ,the ,moon's ,path with ,respect to the ,sun and the ,earth4 ,it may be well to add to what is said in the text about the orbit of the moon1 that1 while the moon does perform a revolution around the earth once a month1 yet her orbit is drawn out1 by the common motion of both earth and moon around the sun1 into a long curve1 whose radius is continually changing1 but which is always concave toward the sun4 ,this is illustrated in the accompanying diagram4 ,suppose we start with the earth at ,a4 ,the moon is then between the sun and the earth1 or in the phase of ,new ,moon4 ,the earth's orbit at this point is more curved than the moon's1 and the earth is moving relatively faster than the moon4 ,at ,b 7,first ,quarter7 the earth is directly ahead of the moon4 ,but now the moon's orbit becomes more curved than the earth's and it begins to overtake the earth4 ,at ,c 7,full ,moon7 the moon has come up even with the earth1 but on the opposite side from the sun4 ,from that point to ,d 7,last ,quarter7 the moon gains upon the earth until she is directly ahead of it4 ,then1 from ,d to ,e 7,new ,moon1 once more7 the earth gains until the two bodies are in the same relative positions which they occupied at ,a4 ,throughout the entire lunation1 however1 notwithstanding the changes which the shape of the moon's orbit undergoes1 the latter is constantly concave toward the sun4 ,this shows that the sun's attraction is really the governing force1 and that the attraction of the earth simply serves to vary the form of the moon's path1 and cause it to move in a virtual ellipse with the earth for its focus4 ,i glanced over her shoulder1 and saw a smudgy scallop in the moon's edge4 8,really10 ,i said1 8,i am ashamed of myself4 ,there is an eclipse of the moon to-night1 and ,i had positively forgotten it6 ,what you see is the shadow of the earth1 which has the form of a long cone stretching away more than eight hundred thousand miles into space1 and whenever our satellite at the time of ,full ,moon gets nearly in a direct line with the earth and the sun1 it passes through that shadow and undergoes an eclipse4 ,that is what is happening at the present moment40 8,and the shadow has a round form because the earth is round1 ,i suppose40 8,certainly2 the shadow of a globe must have a circular outline4 ,but the shadow of the earth1 although it finally diminishes to a point1 is1 at the moon's distance1 still about #e1gjj miles in diameter1 or more than two and a half times the diameter of the moon4 ,in consequence of the motion of the earth in its orbit around the sun1 its shadow constantly moves eastward1 like a great pencil of darkness sweeping straight across the heavens1 but invisible to us except when the moon1 traveling eastward faster than the shadow1 overtakes and passes through it4 ,this does not by any means happen at every full moon1 because1 for a reason which ,i shall explain presently1 the moon usually passes either above or below the shadow of the earth1 and thus escapes an eclipse4 ,when an eclipse does occur it lasts a long time because the shadow is moving in the same direction as the moon4 ,the moon must pass entirely through it before the eclipse ends4 ,on this occasion the moon will be in the shadow more than three hours1 and during an hour and a half she will be totally immersed4 ,we shall have plenty of time1 then1 to observe the phenomenon1 and after you have satisfied your curiosity a little by watching the slow advance of the shadow movement across the moon1 we can return to our diagram and finish its explanation before the eclipse becomes total40 ,accordingly1 after having watched the progress of the eclipse for half an hour1 during which time the shadow began perceptibly to diminish the moonlight in the park1 we returned to the lamplight and the diagram on the table4 8,i was saying10 ,i resumed1 8that another interesting thing in addition to the cause of the moon's changing phases is represented here4 ,you observe that a little cross stands on each of the four circles representing the moon1 and that1 in every case1 the cross is in the center of that side of the moon which faces the earth4 ,in fact the position of the cross upon the moon is fixed and invariable1 and it always points toward the earth because the moon makes exactly one rotation on her axis in the course of one revolution around her orbit1 or1 as it is often called1 one lunation4 ,we know that this is so because we always see the same features of the lunar surface1 no matter where the moon may be situated4 ,this is true although1 in consequence of the phases1 we cannot see the whole face of the moon except when she is full4 ,but whether it is the ,new ,moon1 or ,first ,quarter1 or ,full ,moon1 or ,last ,quarter1 or ,old ,moon1 that we look at1 the mountains and plains visible are identically the same4 ,if the moon did not turn once on her axis in going once around the earth we would see all of her sides in succession1 although only at ,full ,moon could we see an entire hemisphere illuminated by the sun4 ,at ,old and ,new ,moon the side presented to the earth would be just the opposite to that presented at ,full ,moon4 ,at ,last ,quarter the side facing the earth would be the opposite to that facing the earth at ,first ,quarter40 8,but1 tell me10 said my friend1 8how did the moon ever come to so humiliating a pass that she must be forever turning on her heel to face the earth80 8,that10 ,i replied1 8is a result of the same forces which originally separated her from the earth and gradually pushed her off to her present distance4 ,in a word it is due to #8tidal friction4' ,before the moon had solidified1 the attraction of the earth raised huge tides in her molten mass4 ,these tides acted on the rotating moon like brakes on a wheel1 and at length they slowed down her rotation until its period became identical with that of her revolution around the earth4 ,for the mathematical calculations on which all this is based you must go to ,professor ,darwin's book on #8,the ,tides1' or some similar technical treatise2 but ,i imagine you will never do that40 8,not just at present1 ,i assure you4 ,i do not know what unexpected ambition for the acquirement of scientific knowledge may arise after ,i have seen those wonders that you have promised to show me in the moon1 but1 for the moment1 ,i am content to accept your statement of the simple fact40 8,good60 ,i replied4 8,and now1 perhaps1 you will have the patience to listen to an explanation of a very important relation which exists between the moon and the earth4 ,we are led to it by what ,i have just said concerning tides4 ,you know1 of course that the tides in the oceans are due principally to the attraction of the moon4 ,the sun also raises tides in the seas1 but the moon1 being so much nearer than the sun1 is the chief agent in producing them4 ,sometimes the moon and the sun act together2 at other times they pull in different directions4 ,at ,full ,moon and at ,new ,moon they pull together1 because then they are either on opposite sides of the earth1 or both on the same side4 ,at such times we have the highest tides in all our seaports4 ,that occurs about once every fortnight4 ,but when the moon is at either ,first or ,last ,quarter1 as you will perceive by looking at the diagram1 her position1 as seen from the earth1 is at a right angle with a line drawn to the sun4 ,then the sun raises tides in one direction and the moon in another direction4 ,the result is that at such periods the tides are lowest4 ,an exact knowledge of these things is very important for mariners because there are harbors whose channels can be navigated by large ships only when the tides are high4 ,tables predicting the times and heights of the tides have been prepared for all the principal seaports of the world4 ,in truth1 the moon renders important services to the inhabitants of the earth1 not merely in supplying them with a certain amount of light in the absence of the sun1 but also in enabling them to navigate waters which are too shallow for ships except when deepened by the tide4 ,the tides also1 in many cases1 serve to scour out channels and keep them open40 8,really1 ,i am quite interested1 and the more so because ,i find the moon1 like a dutiful daughter1 trying to be of some use to her mother4 ,but have ,i not heard that the tides occur on both sides of the earth at once1 and not simply on the side where the moon happens to be at the time8 ,please tell me how that can be so80 8,a complete reply to your question would carry us into the realm of mathematical physics1 but perhaps ,i can throw a little light upon the matter with the aid of this second diagram4 ,illustration3 ,the ,moon and the ,tides4 8,the eclipse is not yet total10 ,i continued1 glancing out of the door1 8and we can finish our explanation before it becomes so4 ,have the kindness1 then1 to look at the diagram4 ,suppose ,e to be the center of the earth1 and ,m the center of the moon4 ,the protuberant portions of the earth ,c ,a ,d and ,d ,b ,c represent the waters of the ocean pulled away from the surface of the earth1 if ,i may so describe it1 by the moon's attraction4 ,you are probably aware that the attraction of gravitation varies with the distance of the attracting body4 ,the distance from the center of the earth to the center of the moon is about #bci1jjj miles4 ,but the earth being nearly #h1jjj miles in diameter1 the surface of the ocean at ,a is about #d1jjj miles nearer to the moon than is the center of the earth ,e4 ,it follows that the force of the moon's attraction is greater at ,a than at ,e4 ,if the water of the ocean were a fixed1 solid part of the earth there would be no perceptible effect resulting from this difference in the amount of the moon's attraction4 ,but since the water is free to move1 to a certain extent1 it yields to the attraction1 and is drawn up a little toward the moon4 ,at the same time it is1 in effect1 drawn away from ,c and ,d4 ,the consequence is the production of a tide on the side facing the moon4 8,now1 for the other tide1 produced at the same time on that side of the earth which is turned away from the moon4 ,the point ,b is about #d1jjj miles farther from the moon than ,e2 consequently the moon's attractive force is less at ,b than at ,e4 ,from this it results that the body of the earth is more forcibly attracted by the moon than is the water at ,b4 ,the earth therefore tends to move away from the water at that point1 and another tidal protuberance is produced1 with its highest part at ,b4 ,i should add that while the water of the ocean is1 to a certain degree1 free to respond to these differences of attraction1 the earth itself1 being solid1 can only move as a single body1 and1 mathematically1 we may regard it as if its entire mass were concentrated at the center ,e4 ,please remember1 however1 that this explanation is only elementary1 only intended as a graphic representation of the tides1 and not as a mathematical demonstration of the way they are produced4 ,such a demonstration would only be suited to one of the technical books that you have not found as interesting as--some other branches of literature4 8,there is just one other thing to which ,i must ask your attention1 and then we shall return to the moon herself and the phenomena of the eclipse now in progress4 ,you will notice in the diagram1 that two arrows show the direction in which the earth is continually rotating on its axis1 and that a dotted curve1 terminating with an arrow point1 indicates the course of the moon in her orbit surrounding the earth4 ,the rotation of the earth is so much more rapid than the motion of the moon that the points ,a and ,b are carried out of the line drawn from the center of the moon to the center of the earth1 in the direction of the arrows4 ,from this it follows that the tides are never directly under the moon1 or exactly opposite to her1 but sweep in great waves round the globe4 ,the tides produced by the attraction of the sun are only about two fifths as high as those caused by the moon4 ,as ,i have already explained they are sometimes superposed upon the lunar tides--at ,new and at ,full ,moon--and sometimes they are situated at right angles to the lunar tides--at ,first and ,last ,quarters40 8,but the eclipse60 interrupted my friend1 whose attention had evidently begun to wander4 8,i think the totality of which you spoke must be at hand1 for notice how dark the park has become1 and the fireflies are so brilliant under the trees40 ,the total phase of the eclipse was1 indeed1 beginning1 and we stepped out on the lawn before the door to watch it4 ,the moon had now passed entirely within the earth's shadow1 but although her light was almost completely obscured as far as its power to illuminate the landscape was concerned1 still the face of the moon was dimly visible1 as if concealed behind a thick veil4 ,certain parts of it had a coppery color1 producing a very weird effect4 8,dear me60 exclaimed my companion1 8,i did not think it would look like that6 ,i navely supposed that one could not see the eclipsed moon at all1 but that she either disappeared or was turned into a kind of black circle in the heavens4 ,and what a strange color she has6 ,positively it fills me with awe40 8,it is very rare10 ,i said1 8for the moon to become invisible during an eclipse4 ,that can only occur when the earth is enveloped in clouds40 8,indeed1 and what have the clouds to do with it8 ,if the solid body of the earth cannot cast a shadow dense enough to hide the moon1 ,i should not expect things so evanescent as clouds to be more effective40 8,it is all owing to the earth's atmosphere10 ,i replied4 8,if our globe were not surrounded with a shell of air the moon would always be totally invisible when eclipsed4 ,but the atmosphere acts like a lens of glass inclosing the earth2 that is to say1 it refracts1 or bends the rays of sunlight around the edge of the earth on all sides1 and throws a portion of them even into the middle of the shadow1 at the moon's distance4 ,it is these refracted rays which cause the singular illumination that you perceive on the moon4 ,but when1 as occurs only occasionally1 all that part of the atmosphere which surrounds the earth along the edge visible from the moon is filled with clouds1 the air can no longer transmit the refracted rays1 and then1 no light being sent into the shadow1 a #8dark eclipse1' as astronomers call it1 results4 ,an eclipse of the sun is a very different thing4 ,that is caused not by a shadow but by the opaque globe of the moon passing between the earth and the solar orb4 ,when this occurs the sun is completely hidden behind the moon1 and only its corona1 which projects beyond the moon on all sides1 is visible40 8,indeed6 ,i supposed that all eclipses were very much the same thing40 8,by no means4 ,an eclipse of the sun is an event of extreme importance to astronomers1 while an eclipse of the moon possesses comparatively little scientific interest40 8,i do not see why that should be so40 8,it is so1 for the reason that when the sun is eclipsed1 as ,i have just told you1 the solar corona1 which cannot be seen at any other time owing to the overpowering brilliance of the solar orb1 becomes plainly visible1 and by studying the form and other particulars of the corona astronomers are able to draw most important conclusions concerning the constitution of the sun1 the mechanism of its radiation1 and its effects upon the earth4 ,during an eclipse of the moon1 on the other hand1 practically nothing new is revealed1 and1 accordingly1 astronomers pay comparatively little attention to such phenomena4 ,lunar eclipses1 however1 possess a certain importance1 because by predicting the times of their occurrence and then comparing the predictions with the events1 something is learned about the motions of the moon4 ,i should add that recently eclipses of the moon have been carefully watched by a few astronomers1 notably by ,prof4 ,william ,h4 ,pickering1 because of peculiar effects which seem to be produced at certain points on the moon by the chill which the shadow casts upon her surface4 ,there are also interesting observations to be made concerning the reflection of heat from the moon during an eclipse4 ,but1 upon the whole1 a lunar eclipse is mainly interesting as a curious spectacle1 and as a test of the correctness of astronomical calculations of the motions of the heavenly bodies4 8,i may add1 however1 that eclipses of the moon have been of some use to historians in fixing the dates of important occurrences thousands of years ago4 ,this is possible because astronomers can by calculation ascertain the times of eclipses in the past as well as in the future4 ,perhaps the most interesting of all instances of this kind is that which relates to the date of the beginning of the ,christian era4 ,this has been fixed by means of an eclipse of the moon mentioned by the ancients as having happened the night before the death of ,herod1 king of the ,jews40 8,it seems to me10 said my friend1 8that the faint light on the moon's face is continually changing4 ,it does not appear constantly to have the same tint4 ,while we have been standing here1 ,i have noticed that some parts have grown darker and others lighter1 and that the red color on the right has become a little more intense40 8,yes1 and that1 too1 is no doubt caused by the earth's atmosphere4 ,while the eclipse lasts1 the earth is rapidly rotating1 and consequently new parts of the atmosphere are continually brought to the edge where their refractive effects come into play4 ,if the atmosphere at the edge of the earth is a little more or a little less dense its refraction varies proportionally4 ,then1 changes in the relative clearness or cloudiness of the air are taking place all the time1 and these are reflected in the illumination on the moon40 8,it seems to me1 then1 that the earth would present a very remarkable spectacle if we were now on the moon looking at it40 8,surely it would4 ,seen from the moon the earth appears several times larger than the sun4 ,for the people of the moon1 if we imagine them to exist1 an eclipse of the sun is now in progress4 ,for them the earth now occupies the same relative position which the moon occupies for us just before it appears in the west as ,new ,moon4 ,they cannot see it except in silhouette as it passes over the sun4 ,more than an hour ago1 if they were watching 7and if they exist1 and are intelligent beings we may be sure that they were on the alert71 they suddenly perceived a black round-edged notch in the side of the sun4 ,instead of being more or less cloudlike and indefinite in outline1 like the shadow of the earth on the moon1 this notch appeared to them perfectly black and smooth4 ,at a glance1 they saw that the body producing it was much larger than the sun4 ,as the sun's disk was gradually hidden behind the earth the shadow of the latter fell over them1 until the sun was wholly concealed4 ,then--and this is true at the present moment--they perceived that the huge disk of the earth was ringed with light1 probably of a reddish tinge4 ,this light1 as ,i have already indicated1 is that which the atmosphere refracts around the edge of the earth40 8,it must be truly a magnificent sight10 said my companion4 8,yes1 and it is doubtless rendered far more magnificent by the other phenomena which our people at the moon have before their eyes4 ,in consequence of the virtual absence of air there1 an observer on the moon would see all the stars1 even in full daylight1 blazing in a jet black sky4 ,the brilliance of the stars and of the ,milky ,way would hardly be increased by the hiding of the sun1 but probably the long silvery streamers of the solar corona would glow perceptibly brighter when seen projecting out on each side of the enormous disk of the earth40 8,but is it true that the moon has no air80 8,very1 very little1 and what little she has is probably different in composition from our atmosphere4 ,some observations seem to indicate that there is a very rare atmosphere on the moon1 but to us it would seem a perfect vacuum4 ,we could not breathe there at all40 8,how then do those intelligent inhabitants1 whom you have pictured for me watching the earth at this moment1 manage to survive80 8,ah1 ,i did not say that there actually are inhabitants in the moon4 ,i only imagined them to exist for the sake of showing how this eclipse would appear seen from the moon4 ,still1 we cannot be absolutely sure that there are no inhabitants on the moon4 ,even without air like ours it is conceivable that beings of some kind1 and intelligent beings1 too1 might exist there4 ,however1 astronomers have never yet been able to discover evidence of their presence4 ,lately1 indications have been found of the probable existence of vegetation on the moon1 but ,i shall speak of that later1 when with the aid of the series of lunar pictures made at the ,yerkes observatory we try to make a #8photographic journey' in the moon40 8,but tell me1 has the moon always been so airless80 8,that is another unsettled question4 ,some astronomers have thought that formerly1 ages ago1 the moon possessed a much more dense atmosphere than she has at present4 ,having separated from the earth1 in the way ,i have described1 it is natural to suppose that at first she may have had an atmosphere very like ours4 ,the explanation of its disappearance which was once generally accepted was that it had been absorbed into the lunar rocks1 as the globe of the moon cooled off4 ,but recent progress in our knowledge of the nature of the gases composing the atmosphere has led to a different explanation4 ,this assumes that nearly all of the moon's atmosphere has flown away from her because the lunar globe does not possess sufficient gravitating force or attraction to retain it4 ,if the mass of the earth were no greater than that of the moon1 our atmosphere also would probably have escaped by flying off into space40 8,but how1 and why1 do these gases fly away80 8,they do it by virtue of what physicists call their molecular velocity4 ,a gas1 of whatever kind1 is a mass of molecules which are in continual vibration1 moving in all directions among one another with very great velocities4 ,these velocities have been measured1 and it has been found that the molecules of nitrogen1 one of the components of the air1 move at the rate of two miles in a second4 ,the velocity of the molecules of oxygen is a little less2 that of the molecules of hydrogen is very great1 nearly seven and a half miles in a second6 ,now1 it is also known that the attraction of the earth is sufficient to retain permanently upon its surface all moving particles or molecules which have a velocity less than seven miles in a second1 while the attraction of the moon only suffices to retain those whose velocities fall under a mile and a half in a second4 ,so you perceive that all of the gases ,i have named would soon escape from the moon1 even if they were present upon it at the beginning of its history4 8,i must also remind you that there is no water upon the moon1 at least not in the form of rivers1 oceans1 lakes1 ponds1 or even of clouds4 ,but ,professor ,pickering has recently noted certain appearances which may be due to the formation of a kind of hoar frost4 ,if there were once oceans upon the moon1 as the great plains1 called maria1 or seas1 in the lunar charts1 seem to indicate1 they1 too1 have escaped by evaporation4 ,the velocity of the molecules of water vapor is two and a half miles per second1 a mile greater than the #8critical velocity' which the attraction of the moon would be able to control40 8,but10 interrupted my companion1 8,i am puzzled to understand how you know so much about the power of the moon to hold things40 8,it is really quite simple10 ,i replied4 8,the attraction of gravitation1 which is a property belonging to all known bodies1 is measured by the mass1 or amount of matter1 in a body4 ,it also varies with the distance between the attracting and attracted bodies4 ,we know1 by means which ,i shall not attempt to describe here1 the mass both of the earth and of the moon4 ,we also know the size of both of these bodies4 ,they attract objects as if their entire masses were concentrated at their centers4 ,a body of a certain kind and size at the surface of the earth weighs just one pound4 ,if the earth were reduced to half its actual diameter1 while retaining the same mass or amount of matter1 more closely packed together1 the body which now weighs one pound would then weigh four pounds1 because it would be twice as near to the center of the earth as before1 and the attraction of gravitation varies according to the square of the distance from the center4 ,as the distance diminishes the force increases4 ,the square of two is four1 therefore the body would be attracted with four times the force which it experiences at present4 ,now1 the moon is not only much smaller than the earth1 but its average density1 or the closeness with which the molecules of its rocks are packed together1 is less4 ,it results from these facts that the ratio of the entire mass of the moon is to that of the earth as one to eighty-one4 ,hence the inherent power of the moon to attract bodies is less than one-eightieth as great as the earth's4 ,if the diameter of the moon were the same as that of the earth1 a body weighing one pound on the earth would weigh only one eighty-oneth part of a pound on the moon4 ,but the diameter of the moon is less than one quarter as great as that of the earth4 ,it follows that bodies on the moon are almost four times 7more accurately about #c4ff times7 nearer to the center of attraction4 ,this fact must be taken into account in calculating the force of gravity on the moon's surface4 ,as far as the mass of the moon is concerned1 bodies on her surface experience less than one-eightieth of the attractive force which the earth exercises upon bodies on its surface1 but this is so far counterbalanced by their greater nearness to the center1 that the actual attraction upon them is about one sixth of that which they would experience on the earth40 8,thank you10 said my companion dryly1 8your explanation appears to me to be very scientific40 8,not by any means as scientific as it might be1 or as it ought to be10 ,i replied1 laughing4 8,but1 really1 if you wish to understand these things you should not be too much afraid of the bugbear #8science4' ,science makes the world go nowadays1 and everybody ought to know a little about it1 just as everybody with any pretensions to education a hundred years ago had to learn more or less ,greek and ,latin4 ,but let me continue a little farther4 ,since the force of attraction on the moon is only one sixth as great as it is on the earth1 the weight of all bodies is in the same proportion4 ,pardon me if ,i guess at your weight2 it is1 perhaps1 #abj pounds4 ,very well1 translated to the moon you would weigh only #bj pounds40 8,dear me1 then skipping the rope may be the favorite pastime of middle-aged ladies on the moon40 8,and throwing somersaults that of gray-haired lunar gentlemen4 ,let me tell you of one very interesting consequence of the small force of the moon's gravity1 which affects not merely the weight of bodies but the flight of projectiles1 and1 indeed1 all motions of every kind4 ,you will see1 when we come to the photographs1 that some of the lunar volcanoes are of a magnitude almost incredible4 ,this is doubtless due to the fact that the ejections from volcanic craters there were able1 with no greater expenditure of explosive force1 to attain an elevation six times that which they would attain if thrown from a volcano on the earth4 ,during the eruption of ,vesuvius in ,april1 #aijf1 the column of smoke1 steam1 and cinders from its crater reached1 according to the measures of ,professor ,matteucci1 a maximum height of about eight miles4 ,on the moon the same force would have blown these things almost fifty miles high6 ,it is not difficult1 in view of such facts1 to see how the giant volcanic craters and mountain rings of the moon were formed40 ,in the meantime the eclipse continued1 and1 having tired of watching it1 we returned to the drawing-room4 8,when shall we see these famous photographs and begin our imaginary journey in the moon80 my companion asked4 8,to-morrow10 ,i replied4 8,but ,i shall have to demand one more brief exercise of your patience this evening1 while ,i finish with this subject of eclipses40 8,then we are not through yet80 8,not quite1 for ,i have not yet told you why the moon is not eclipsed every time she approaches the earth's shadow1 and why she does not eclipse the sun once every month at the time of ,new ,moon40 8,well1 tell me then1 and ,i promise to be as interested as possible2 only please don't talk any more mathematics than is absolutely necessary40 8,very well1 ,i'll spare your attention as much as possible4 ,to begin with the eclipses of the moon3 ,the reason why they are not of regular monthly occurrence is simply because the orbit of the moon is a little inclined1 about #e1 to the orbit of the earth4 ,even then there would be an eclipse once every month if the orbit of the moon were fixed in space1 and if the point where that orbit crosses the plane of the earth's orbit were always directly opposite to the sun4 ,but instead of being fixed in position the orbit of the moon has a curious motion of revolution of its own4 ,this causes the two opposite points1 where it crosses the plane of the earth's orbit1 and which are called the moon's #8nodes1' to move continually onward in a direction opposite to that in which the moon revolves1 but much more slowly4 ,a period of about nineteen years is required for the moon's nodes to complete a revolution4 ,the consequence is that the nodes are not always in line with the earth and the sun1 and except when they are nearly in line no eclipse can occur4 ,to enter into a complete explanation of this would require more #8mathematics' than you would like1 but what ,i have said may at least serve to give you an idea of the reason why eclipses are comparatively of rare occurrence40 8,i think ,i understand the reason sufficiently4 ,but what a complicated affair you astronomers make of what1 it seems to me1 should really be a very simple thing40 8,it is like a sewing machine10 ,i replied1 8which seems very simple when you see it running smoothly1 and do not trouble yourself about all the various parts of its mechanism4 ,but if you undertake to explain to yourself1 or to make clear to another person1 exactly how the machine works1 you find that your attention is rather severely taxed1 and that the apparent simplicity is based upon no little complexity of construction and interaction of parts4 ,you will have understood from what ,i have said1 that the reason why the moon does not eclipse the sun once every month is based upon the same fact1 namely1 the inclination of the moon's orbit to the plane of the orbit of the earth2 and that when she does eclipse the sun her nodes must be somewhere near a line drawn from the earth to the sun4 ,there is one broad difference between an eclipse of the moon and an eclipse of the sun which ,i have not yet mentioned4 ,this arises from the fact that the moon being so much smaller than the earth1 her shadow1 when she hides the sun1 does not cover the entire earth1 as the earth's shadow covers the whole moon1 but comes almost to a point before reaching the earth4 ,the average length of the moon's shadow is only #bcb1aej miles1 #f1fij miles less than the average distance between the moon and the earth4 ,but since1 in consequence of the eccentricity of her orbit1 the moon's distance is continually varying1 the length of her shadow also varies to the extent of about #d1jjj miles each way4 ,thus it may be as short as #bbh1cjj miles1 or as long as #bcf1jej miles4 ,when the greatest length of the moon's shadow coincides with her least distance from the earth 7#bba1fjj miles71 her shadow extends more than #ah1jjj miles beyond the earth4 ,under such circumstances its diameter at the surface of the earth is about #afg miles4 ,that is the greatest diameter that the shadow of the moon can have at its intersection with the earth4 ,ordinarily1 when it reaches the earth at all1 its diameter is less than #ajj miles1 and often very much less4 ,if the earth and the moon were motionless during an eclipse1 her shadow would form a round1 dark spot on the earth1 and all observers within the circumference of that spot would behold the sun totally eclipsed4 ,but1 in consequence both of the motion of the moon in her orbit1 and the rotation of the earth on its axis1 the shadow spot moves swiftly in an easterly direction over the earth's surface1 forming what is called the path of the eclipse4 ,the astronomer calculates beforehand across what parts of the earth the path will lie1 and selects his points of observation accordingly4 8,when the length of the shadow is too small to reach the earth1 the moon appears projected against the sun as a round black disk1 hiding the center of the solar orb1 but leaving a brilliant ring all around4 ,such phenomena are called annular eclipses4 ,there are about three annular eclipses for every two total ones4 ,when the moon1 as often occurs1 does not traverse the center of the sun's disk1 as seen from any part of the earth1 a partial eclipse is the result4 ,this means that only a portion of the sun is hidden by the moon4 ,even a total eclipse appears as a partial one to observers who are not placed within the limits of the shadow path40 8,but it seems to me10 said my friend1 8you have hedged round your eclipses with so many difficulties1 what with the tip of the moon's orbit1 and what with the shortness of her shadow1 that they must be very few in number4 ,yet ,i often hear of an eclipse1 although ,i have never seen one before to-night40 8,they are not so rare as you might suppose10 ,i replied4 8,it is not necessary1 in order that an eclipse1 either partial1 or total1 or annular1 may occur1 that the moon's nodes be in a direct line with the centers of the sun and the earth4 ,the moon may be a few degrees out of line1 and yet either pass into the earth's shadow or be seen crossing the sun from one point or another on the earth4 ,there are about #gj eclipses in every eighteen years1 #da of the sun and #bi of the moon1 but the number varies a little4 ,generally there can be no more than two eclipses of the moon in any one year1 but it is possible for three to occur4 ,the greatest number of solar eclipses in a year is five1 but this is very rare1 the usual number being two4 ,in fact1 there must be at least two solar eclipses in a year1 but there are many years which have no eclipses of the moon at all4 ,and now1 ,i think ,i have said all that is necessary about eclipses1 and we arrive very opportunely at the end of the discourse1 for behold the moon is passing out of the shadow1 and her light begins once more to glow in the park40 ,this was indeed the case4 ,going to the door1 we saw the earth's shadow slowly withdrawing from the face of the moon1 while the landscape was brightening under her returning rays4 ,for a few minutes we watched1 in silence1 the brilliant spectacle4 ,then my companion turned to me4 8,would you know my whole thought80 she asked4 8,i fear that ,i cannot recall many of the scientific facts you have just been telling me1 but for them ,i can go back1 at need1 to the books4 ,yet one thing ,i feel that ,i have certainly gained4 ,it is a sense of friendly1 companionable interest in the moon4 ,henceforth she will be more to me than she ever was before4 ,i shall always be conscious1 when looking at her face1 that she is the offspring of the earth1 and that there exists between these two bodies an intimacy that ,i had never imagined possible4 ,for me your tides and your eclipses seem an inarticulate language1 a caressing exchange of communications between these two celestial beings of one blood4 ,to my mind they are1 in a certain sense1 personalities1 and1 as a creature of the earth1 ,i feel now my relationship to the moon40 8,very good10 ,i replied4 8,all science and all forms of knowledge are rooted in the imagination4 ,to-morrow we shall begin with the photographs1 and many most interesting things that ,i have not yet mentioned will then naturally present themselves before us40 8,good night then10 said my companion1 8and to-morrow ,i shall count upon the delights of a photographic journey in the moon40 ---------------------------------------- -------------------------------- ,i ,,new ,,moon ,,to ,,first ,,quarter ---------------------------------------- -------------------------------- ,i ,,new ,,moon ,,to ,,first ,,quarter ,,at breakfast the next morning ,i asked my friend if she still had sufficient curiosity concerning the moon to induce her to undertake the contemplated journey amid lunar scenes4 8,yes1 surely10 she replied4 8,my dreams last night were filled with wonderful spectacles2 great cones of shadow flitted continually through the heavens1 eclipsing1 in turn1 moon1 sun1 and stars2 and ,i stared1 as it seemed1 for hours at strange faces veiled behind a maze of mathematical diagrams covering the moon4 ,i am not sure that your discourses have made me scientifically much wiser1 but ,i feel that my imagination is sufficiently aroused to enable me to enjoy the photographic excursion that you have proposed1 and ,i am quite ready to start at once40 8,excellent60 ,i said1 producing my portfolio4 8,here then are the photographs which ,i trust will enable us1 in imagination1 to spend an interesting month upon the moon4 ,these photographs were made at the ,yerkes observatory and they represent the moon1 as you will perceive1 in all of her principal phases1 beginning with the narrow crescent of the ,new ,moon1 and ending with the similar1 but reversed1 sickle of the ,old ,moon40 8,let us take them out into the park under the trees10 my friend suggested4 ,the shafts of morning sunshine1 falling through the branches and illuminating the broad lawns and brilliant flower-beds1 offered the greatest possible contrast with the strange scenes of the preceding night4 ,we chose the shadow of a huge elm1 and had a table placed there for our accommodation4 ,on this ,i spread the photographs1 and my companion began to examine them with many expressions of interest4 8,it is not often10 ,i said1 8that science finds so flattering an audience40 8,and ,i hope1 surely1 never so small a one10 she responded1 laughing4 8,but you must admit that science very seldom presents herself in so attractive a form as that of these pictures40 8,they are indeed of the highest excellence10 ,i replied4 8,it is the very moon herself that you see there40 8,but are you certain that they have not been embellished8 ,has not the hand of an artist retouched and improved them--particularly these large ones that seem to contain a thousand curious things which ,i can hardly believe really exist on the moon80 8,no10 ,i said1 8there is nothing fictitious or imaginary in what you see4 ,the only art displayed here is that of the astronomer-photographer1 whose greatest ambition is to make his pictures absolutely true to nature4 ,a defect in one of his plates1 producing the appearance of a speck of light or shadow which does not actually exist1 causes him as much distress of mind as you would experience upon hearing a false note from your piano4 ,indeed1 the astronomer is so desirous of having nothing but the truth represented in his pictures that he often prefers1 for his own study1 the original negatives alone1 because every time that they are reversed to make a #8positive' copy something is sure to be lost1 and some slight defect is certain to be introduced4 ,let us begin1 if you please1 with the series of smaller pictures showing the various phases1 and the gradual advance of daylight across the moon's surface4 ,take first the photograph which ,i have labeled ,no4 #a4 ,it shows the ,new ,moon when it is between three and four days old4 ,you must often have seen it in that form in the western sky soon after sunset4 ,photographs of the ,new ,moon have been made when the crescent is still narrower than that here shown1 but there is no such photograph in this series1 and it would possess little interest for you because almost no details of mountains1 craters1 and plains would be visible4 ,it is hardly possible to make a good photograph of the moon when it is only one or two days from the sun in its monthly journey1 on account both of the glare of the solar light in our atmosphere and of the nearness of the moon to the horizon1 where the air lacks transparency and steadiness4 ,in the photograph before us you will observe a great number of strange forms and shadings4 ,i shall tell you what these are presently1 but first let me call your attention to the fact that the picture does not exhibit a phenomenon which you would behold if you were actually looking at the moon in the phase here represented4 ,you see here the ,new ,moon very clearly1 but not the ,old ,moon in her arms40 8,indeed6 ,it is a pity that the photograph does not show so interesting a sight40 8,yes1 it is a pity4 ,the cause lies in the defect of light from what ,i have called the #8,old ,moon4' ,the part that we see in the photograph is illuminated with sunshine1 while the remainder of the moon reflects only the earthshine1 which is too faint to be photographed 7at least with the amount of exposure required to make a good picture of the brightly lighted crescent72 although1 as ,i have said1 you would see it clearly if you were looking at the ,new ,moon herself40 ,illustration3 ,,no4 #a4 ,,february #ai1 #aijd2 ,,moon',s ,,age #c4he ,,days4 8,but10 interrupted my companion1 8do you mean to tell me that the earth illuminates the moon80 8,surely it does4 ,why not80 ,i replied1 smiling4 8,you must remember that the earth is simply a huge moon to our imagined inhabitants of the lunar world4 ,our globe sends to the moon about fourteen times as much reflected sunlight as the moon sends to the earth4 ,the consequence is than an earthlit night on the moon is far more brilliant than a moonlit night on the earth40 8,then why do we not always see the moon shining with light from the earth80 8,it is a question of contrast4 ,you cannot see a faint light in the immediate presence of an overpoweringly brighter light4 ,the part of the moon that the sun illuminates is in the full glare of day1 and this is so much more brilliant than the reflected earthlight that that portion of the moon which enjoys only the latter is not visible to us1 except for a few days after ,new ,moon1 when the amount of light from the crescent is not yet great enough to dazzle our eyes and hide the rest from sight4 ,i should advise you when the next ,new ,moon occurs--you can find the date in any almanac--to look at it in the western sky4 ,you will see in addition to the bright crescent the full round orb of the moon1 shining faintly1 with a dull1 rather copperish1 tint1 and you will find it interesting1 then1 to remember that that light is reflected from our earth4 8,and now10 ,i continued1 8let us examine our photograph more closely4 ,there is one remark that ,i had expected which you have not made2 it concerns the position of the crescent4 ,you observe that it is bowed toward the left4 ,if you saw it with the naked eye in the sky it would be bowed toward the right1 or toward the place of sunset4 ,the reason is that the photograph presents the moon as seen with a telescope1 which reverses objects1 turning them top for bottom4 ,in this picture1 and in all the others that we shall examine1 the southern part of the moon is at the top and the northern part at the bottom1 the western part at the left and the eastern part at the right4 ,the first thing that you probably notice in the photograph is a conspicuous oval plain1 somewhat below the center of the crescent40 8,yes1 and ,i see clearly why you call it a plain1 for it is perfectly flat and smooth40 8,not quite so flat and smooth as you suppose4 ,this object is one of the most celebrated on the moon4 ,it is the so-called ,mare ,crisium1 or ,sea of ,crises1 as we may translate the name given to it by the astronomers of a couple of centuries ago1 many of whom knew more ,latin than science4 ,owing to its apparent smoothness of surface1 as well as to its form and general aspect1 they took it for a great lake or sea40 8,to tell you the truth10 said my friend1 8if ,i were an astronomer and had discovered this curious place on the moon1 ,i should certainly believe just what your ,latin-loving predecessors believed1 but ,i doubt if ,i should have been capable of inventing so singular a name for it40 8,in the singularity of the names they chose for objects on the moon10 ,i replied1 8their invention is unrivaled4 ,we shall see some remarkable examples4 ,of course they are not at all to be blamed for thinking that this oval spot1 and other similar ones of much greater magnitude1 were seas and oceans4 ,they simply judged by appearance and by analogy4 ,finding mountains on the moon1 they saw no improbability in supposing that there were bodies of water also4 ,they had not the means of knowing1 as we know to-day1 that there is no water on the moon4 ,yet1 perhaps1 they were not so far wrong after all4 ,the ,mare ,crisium certainly has the look of an empty sea bed1 and ,i should not be willing to assert that ages ago it was not filled with water40 8,like the ,great ,salt ,lake1 dried up10 suggested my companion4 8,not exactly1 for the ,great ,salt ,lake dried up would probably present a surface as white as snow1 whereas the ,mare ,crisium is very dark4 ,it must be admitted1 however1 that gradually the white deposit would grow darker1 and there may be much significance in the fact1 which some observers have noticed1 that1 at times1 parts of the dark plains on the moon seem to glitter with minute points of light4 ,your imagination is at liberty to see deposits of salt there40 8,in that case10 said my companion1 laughing1 8,i should prefer to regard the ,mare ,crisium as resembling that wonderful valley discovered by ,sindbad the ,sailor1 whose floor was sprinkled with diamonds40 8,well10 ,i replied1 8science certainly cannot deny the possibility of diamonds on the moon1 for she is par excellence the world of volcanoes1 and one of the most striking discoveries of recent years is that of the intimate association existing between ancient volcanic vents and deposits of diamonds4 ,the diamonds of ,south ,africa are found in lava rocks that cooled off ages ago40 8,then ,i hope that no future ,columbus will find a way to the moon1 for we should have too many diamonds1 and they would lose all their charm40 8,that is true1 but suppose that not only diamonds but even more beautiful gems should be discovered in the lunar world8 ,you surely would not object to a transethereal traffic bringing them to our doors4 ,however1 there is not the slightest prospect that we shall ever be able to go from the earth to the moon4 ,let us resume our examination of the photograph1 and concentrate our attention on the known facts40 ,i then proceeded to tell my friend1 whose interest ,i was delighted to find had not yet begun to flag even in the face of comparatively matter-of-fact statements1 that the ,mare ,crisium is a profound depression1 about #cej miles in length by #bhj in breadth4 ,exactly how far it lies below the general level of the lunar surface we do not know2 but1 at any rate1 if it was ever filled with water it formed a deep1 navigable sea4 ,its encircling mountains1 which appear generally bright in the photograph1 especially along the eastern border1 where the sunlight strikes directly against their slopes1 are in many places steep and abrupt4 ,at one place1 on the southwestern side1 there is a mountainous promontory #aa1jjj feet in height4 ,there are a number of small craters on the floor of the ,mare ,crisium1 but the scale of this photograph is not large enough to show them clearly4 8,you will notice10 ,i continued1 8that there is a kind of bay on the eastern side1 which runs back into the mountains1 and is bordered with high1 steep cliffs4 ,near this point1 on that part of the moon over which the sun has not yet risen1 there is a very remarkable mountain which we shall see in a later photograph4 ,but let us finish with this one4 ,look at the comparatively small oval adjoining the ,mare ,crisium below 7toward the north74 ,it is one of the great crater rings of the moon1 and is named ,cleomedes4 ,it is much larger than it looks1 being nearly #hj miles in its greatest diameter1 and there is a peak on its surrounding wall #aj1jjj feet in height4 ,still farther toward the north you will observe two or three other smaller craters or rings1 which are very interesting when studied with the telescope4 8,now1 please turn your attention to the photograph bearing the number #b4 ,you see again the ,mare ,crisium1 and nearly in the center of the crescent1 and just on the border line between day and night1 a perfect oval ring with a central peak4 ,it is called ,langrenus4 ,it is even larger than ,cleomedes1 being about #ij miles across4 ,it has the form of an oval1 as we see it1 but that is an effect of perspective1 since it is so far round the side of the lunar globe4 ,in reality it is a nearly circular circumvallation1 or rather an almost perfect hexagon1 composed of gigantic mountains including a valley1 in the center of which rises a cluster of peaks #c1jjj feet in height40 8,this second photograph10 interrupted my friend1 8was taken later than the first1 ,i suppose1 since it shows more of the moon's surface40 ,illustration3 ,,no4 #b4 ,,september #bd1 #aijc2 ,,moon',s ,,age #c4hg ,,days4 8,i should have told you that10 ,i replied4 8,yes1 it does represent the moon at a time when more of its surface1 visible to us1 is illuminated by the sun4 ,in fact1 we may regard it as a picture of the moon made about a day later than the other4 ,but ,i must now tell you that these photographs were not all taken in regular succession1 a day apart1 or even two days apart4 ,that was impracticable for reasons that ,i need not explain4 ,some of them were made at one season of the year and some at another4 ,yet taken together they form a sufficiently continuous series to enable us1 with their aid1 to follow the changing aspects of the moon during more than three weeks1 or all that part of a lunation in which the moon is a conspicuous object in the sky40#b ,footnote #b3 ,in addition to what is said in the text concerning the photographs the reader should be informed that1 in consequence of her 8librations10 the moon does not1 all the time1 present exactly the same surface toward the earth4 ,if she did we should never see more than one half of her surface4 ,in fact1 however1 at one time or another1 we see1 in all 7but never at the same time71 about fifty-nine per cent of her surface1 leaving forty-one per cent which is forever invisible because never turned in our direction4 ,the librations1 or 8balancings10 of the moon1 which bring now one and now another portion of the usually invisible hemisphere into view1 are of three kinds3 ,first1 the libration in latitude1 arising from the combined effects of the inclination of the moon's orbit to the plane of the earth's orbit1 and the inclination of her axis of rotation to the plane of her own orbit4 ,when added together these two inclinations make the axis of the moon lean one way or the other with respect to the earth about #f4 ,but1 since the inclination of the moon's orbit to that of the earth is continually varying to a small extent1 the amount of this libration is also variable4 ,its effect is to cause now the ,north and now the ,south ,pole of the moon to incline slightly toward the observer on the earth1 so that he can see alternately a little way round the northern and the southern edges of the moon's disk4 ,second1 the libration in longitude1 which arises from the eccentricity of the moon's orbit1 causing her to move a little faster when she is nearer the earth1 or in perigee1 and a little slower when she is farther from the earth1 or in apogee4 ,in consequence of this1 she gets alternately about #f ahead of1 or behind1 the position which she would have if her orbit were a perfect circle and her motion perfectly uniform4 ,but1 inasmuch as her rotation on her axis is never either faster or slower1 she shows a little of her usually invisible hemisphere on the western side when she is between perigee and apogee1 and a little on the eastern side when she is between apogee and perigee4 ,the accompanying diagram is designed to aid the reader in understanding these effects4 ,illustration3 ,effect of ,moon1 ,varying ,velocity in ,orbit ,producing ,libration in ,longitude4 ,third1 the diurnal libration1 which arises from the fact that the diameter of the earth bears a considerable proportion to the distance of the moon4 ,if the observer were at the center of the earth there would be no effect of this kind1 but being situated about #d1jjj miles from the center1 there is a parallactic effect in consequence of which we see a little around the western side of the moon when she is rising and a little around the eastern side when she is setting4 ,the maximum diurnal libration is a little more than one degree4 ,the maximum libration in latitude is #f #dd1 and that in longitude #g #de4 ,an illustration of the results of libration will be found by comparing photographs ,nos4 #a and #b4 ,they were both taken at nearly the same 8age of the moon10 about three days1 twenty hours1 but under different librations1 so that in ,no4 #b more of the western edge of the moon is visible1 and the crescent appears broader4 ,even more remarkable examples of the results of libration are seen in ,nos4 #f and #g1 and #h and #i4 ,in ,no4 #f1 the moon is actually 8older0 by about half a day than in ,no4 #g1 yet1 owing to libration1 the 8terminator10 or line between day and night on the moon1 is considerably farther toward the east in the latter than in the former4 ,a similar effect is seen in comparing ,nos4 #h and #i4 ,the exact dates and ages of the moon corresponding to these photographs are given in the ,appendix4 8,if you will follow the curve of the terminator toward the south 7upward in the photograph71 you will perceive that there is a long line of ovals1 more or less resembling ,langrenus4 ,the first of these1 darker in appearance than ,langrenus1 is named ,vendelinus40 8,what extraordinary names60 exclaimed my companion1 8and how unpicturesque60 8,yes1 it is true that the invention of the old astronomers who supplied these names seems to have failed a little at times4 ,they did exceedingly well in naming the #8seas' and similar objects1 but for the mountains1 craters1 and ring plains they could think of no better plan than that of attaching to them their own names1 and the names of other savants1 or supposed savants of their time1 or of preceding centuries4 ,and in ,latinizing these names they gave them a kind of uniformity1 which is hardly pleasing to our taste to-day4 ,but let me continue4 ,vendelinus is an extremely beautiful sight when the sunlight strikes its broken walls in such a manner as to bring into prominence1 by contrast with the deep shadows1 the rugged peaks1 precipices1 and ridges of which its very irregular ring is composed4 ,you should see it with a powerful telescope1 especially under the rays of the setting sun4 ,then the bottom of the valley within has been described by ,mr4 ,eiger1 an ,english student of lunar phenomena1 as appearing punctured like a sieve with holes40 8,and what are they80 8,volcanic craters1 probably1 long since extinct40 8,so many volcanoes in one place80 8,oh1 yes4 ,you have been at ,naples and have seen ,vesuvius4 ,but probably you have not visited the ,phlgrean ,fields which lie northwest of ,naples4 ,if you had had a passion for geology when you were in ,italy you would have explored that region1 and there you would have found something not altogether unlike the valley of ,vendelinus in the moon4 ,there is a great number of extinct volcanic craters near ,naples1 and they show how similar in many ways the moon is1 or has been1 to the earth40 8,but1 dear me10 my friend exclaimed1 8are we going to see nothing but burned-out craters and wild1 ragged mountains on the moon8 ,i am sure that ,i should never have thought of visiting ,naples for the sake of looking at its ,phlgrean ,fields40 8,still10 ,i replied1 8you must certainly know that ,pompeii and ,herculaneum and the memories of their tragic fate are the most vivid attraction of ,naples to-day1 although the ,pompeiians have all been dead for almost #b1jjj years4 ,so in looking at these spectacles in the moon we cannot but be interested by the reflection that they are reminders and relics of a wonderful history1 whatever its precise character may have been4 ,the moon seems to me to stand for the most affecting of all tragedies--the passing of a world4 ,when ,i survey its extraordinary landscapes1 it is like looking upon a long-abandoned stage1 whose actors are in their graves1 whose scenery is moldering under a gaping roof1 whose machinery is broken1 whose very traditions are forgotten1 but which yet retains a semblance of its former brilliance4 ,i do not have to imagine inhabitants in the moon at the present day in order to find it interesting4 ,the possibility that it may once have had inhabitants is enough1 remembering its nearness to the earth and the manner of its origin1 to make it the most fascinating thing that the heavens contain40 8,indeed1 ,i had never thought of the moon quite in that way10 was the reply4 8,if you can read a history for me in these craters and ring plains ,i believe ,i shall find them more interesting than ,i expected40 8,i cannot promise you a history as full of romantic details as that of ,herodotus10 ,i said1 8but it may contain nearly as many actual facts4 ,however1 we shall see about that as we go along4 ,let us now return to the inspection of the photograph4 ,be kind enough to look a little above ,vendelinus4 ,you observe there another still larger ring plain1 or walled valley1 with a conspicuous mountain in the center4 ,this is ,petavius4 ,it belongs to the chain of similar formations which includes ,langrenus and ,vendelinus1 but it is more wonderful than either of them4 ,it is nearly a hundred miles long from north to south4 ,for some reason1 as with ,vendelinus1 its ruggedness and complexity of structure are more conspicuous in the lunar afternoon than in the lunar morning4 ,it is a question of the direction in which the light falls across it4 ,a curious thing about ,petavius is the convexity of its vast floor4 ,the center is about #hjj feet higher than the edges along the feet of the surrounding mountains40 8,how do you know that80 8,the shadows tell the story4 ,the height of objects on the moon is measured by observing the length of their shadows under a known inclination of the sun's rays4 ,when ,i stand this book upright on the table1 allowing the sunlight to strike it on one side1 it casts a shadow on the table4 ,if ,i did not know the height of the book1 and could not measure it directly1 ,i could find it out by measuring the length of its shadow1 other simple trigonometrical data1 easily ascertained1 being known4 ,there is an enormous cleft not clearly visible in the photograph1 extending from the central mountains of ,petavius to the southwestern wall of the valley4 ,still farther south1 above ,petavius1 you will notice another conspicuous oval plain and several smaller ones near it4 ,the largest of these is named ,furnerius4 ,they all lay in the morning sunshine1 not far from the terminator1 when this photograph was taken40 8,tell me1 please1 about the #8terminator' of which you have spoken several times4 ,as ,i understand you it is the line between day and night on the moon40 8,yes1 and a very wonderful line it is1 too4 ,there is nothing just like it on the earth4 ,owing to the effects of our atmosphere in dispersing the light1 day and night do not stand face to face with one another on the earth in the same way that they do on the moon4 ,here we have twilight in the evening and dawn in the morning1 and night neither comes nor goes for us with the startling suddenness that characterizes it on the moon4 ,for an hour or two after sunset and before sunrise1 we receive rays of reflected and refracted light from the atmosphere above us1 which spread a soft1 pleasing illumination over the landscape1 and render all objects more or less distinctly visible4 ,but if you were on the moon in certain situations1 the passage from day to night or from night to-day would be as rapid as the falling or rising of a curtain4 ,imagine yourself standing on the western wall of ,vendelinus or ,petavius at the time when this photograph was taken4 ,you would be in a blaze of pitiless1 untempered sunshine1 but glancing down the precipice at your feet you would seem to be looking into a gulf of blackness4 ,but for the light reflected back from the eastern cliff1 and that coming from the earth1 there would be scarcely a ray of illumination on the rocks below you4 ,you would look down into inky darkness1 and would scarcely dare to make a step from fear of falling over the edge of a bottomless pit4 ,at the same time1 as ,i told you last night1 you would see the stars all about you in the sky1 even close to the sun4 8,this is the reason10 ,i continued1 8why the march of day across the moon1 always keeping sharp on the heels of night1 is a spectacle so imposing and unparalleled4 ,it is this wonderful march that we are going to follow with the aid of the photographs4 ,i shall now ask you to give your attention to photograph ,no4 #c4 ,it was made more than a day and a half later than the others1 measured by the age of the moon1 which1 in this case1 was about five days and a half4 ,you notice how in the interval the sunlight has swept eastward over the moon's surface4 ,the ,mare ,crisium is recognizable in the lowest or most northerly1 of three large1 dark plains4 ,the small white oval a considerable distance above it is our old acquaintance ,langrenus1 whose floor and walls are now very brilliant in the full sunshine1 which falls upon them at a high angle4 ,vendelinus and ,petavius are less conspicuous4 ,the broad1 dark plain which has come into view eastward from ,langrenus is the ,mare ,fcunditatis1 which we may translate #8,sea of ,fecundity'6 ,you certainly cannot aver that on this occasion the invention of the old astronomers failed in the matter of romantic suggestiveness4 ,the name calls up pictures of a great body of tranquil water1 fanned by gentle1 stimulating breezes1 filled with fish of every variety1 dotted with vine- and flower-garlanded islets1 and bordered by well-watered shores1 rich with vegetation1 and supporting a numerous and happy population4 ,some such idea of the ,mare ,fcunditatis may have been in the minds of its sponsors a couple of centuries ago4 ,but telescopes have become too powerful in our day to permit us to be any longer deceived as to the actual nature of this singular lunar region4 ,like the ,mare ,crisium1 it may have been the bed of a sea many years ago1 but at the present time it contains no water1 and its shores present an endless succession of fire-scarred cliffs1 peaks1 and volcanoes4 ,the only #8islands' in it are extinct craters40 8,but10 said my companion1 smiling1 8where then is its history80 8,ah60 ,i replied1 8is not this old sea itself history enough8 ,when it has receded sufficiently into the past1 all history loses its details1 and presents only its setting and its grand primary elements4 ,suppose that1 some ages in the future1 you should be an inhabitant of a distant planet1 surveying with a telescope the dried-up basin of the ,atlantic ,ocean4 ,provided only that you were convinced1 in your own mind1 that it had once been an ocean1 with fertile1 inhabited shores1 and with ships sailing upon it1 you would be singularly lacking in imagination if you could not reconstruct its history for yourself4 ,the details could safely be left to your invention and you could change them from time to time to suit your varying moods4 ,terrestrial historians have sometimes done that40 ,illustration3 ,,no4 #c4 ,,july #bi1 #aijc2 ,,moon',s ,,age #e4ed ,,days4 8,but do you believe that the ,mare ,fcunditatis was ever such a sea1 and the scene of such events80 8,that is certainly a very pointed question4 ,questions of that kind are always in order when one is treating of ascertained verifiable facts1 but just now1 you know1 we have wandered a little aside from the straight path of scientific exactitude4 ,still1 ,i will be frank with you and say that ,i really possess no settled opinion concerning the former condition of the moon1 except so far as what we may call its #8geological' history is revealed by its present state4 ,i am sure that the moon was once the seat of tremendous volcanic action1 and ,i think it not improbable that its great depressed plains were once occupied by water1 but as to inhabitants1 ,i know no more about them than you do4 ,still1 ,i am disposed to think that1 as we go on1 you1 at least1 will reach the conclusion that all life has not yet disappeared from the moon4 ,we are going to learn some very suggestive and significant things before we are through4 8,farther toward the south and closer toward the terminator you will see in the photograph a third dark plain with five sides1 the northern one convex and ill-defined4 ,at its upper corner is an incomplete ring plain4 ,this region bears a still more curious name than the ,mare ,fcunditatis4 ,it is the ,mare ,nectaris or #8,sea of ,nectar4'0 8,apparently your astronomers of old took the moon for an abode of the gods40 8,yes1 or for their wine cellar4 ,but we shall get a better look at the surroundings of this ,sea of ,nectar in a later photograph1 and then ,i shall have more to tell you about it4 ,in the meantime let us return to the ,mare ,crisium4 ,to the east 7right-hand side7 of the ,mare ,crisium you will observe a diamond-shaped district1 not very dark1 with a bright point at the corner which faces the ,mare4 ,you could never guess its name4 ,it is called the ,palus ,somnii1 which may be translated #8,marsh of a ,dream4' ,it is a very singular place1 and1 seen with the telescope1 possesses a color which is unique upon the moon1 a kind of light brown1 quite unlike the hue of any of the other plains or mountain regions4 ,it is covered all over with short1 low ridges1 as if its surface had been broken up in a most irregular manner with a giant plow4 ,what the person who named it saw there to lead him to connect it in his mind with dreams ,i have never been able to imagine4 ,the bright point on its western edge is a remarkable crater mountain1 named ,proclus4 ,what that mountain is made of nobody knows1 but it gleams with extraordinary brilliance when the sun strikes it40 8,why may it not be snow-covered80 8,that is a suggestion which has often been made1 but one great objection to it is that we have reason for believing that snow1 at least in such a situation1 cannot exist on the moon4 ,another objection is that only a few of the lunar mountains are comparable in brightness with ,proclus1 and they are not the loftiest ones4 ,upon the whole it is much more probable that the reflecting power of ,proclus is due to the composition of its rocks1 perhaps to broad crystalline surfaces exposed in the sunshine40 8,it is a surprise to me1 then1 that that #8earthly godfather' of lunar wonders1 who had a sufficiently vivid fancy to invent the #8,marsh of a ,dream' close by1 did not name this mountain for some jewel1 real or imaginary40 8,it would have been more poetic1 indeed1 but as ,i have already told you1 the mountains and volcanoes of the moon nearly all bear very prosaic designations1 while a wealth of fancy has been lavished in naming the #8seas' and plains4 ,the astronomer ,riccioli is responsible for most of the commonplace nomenclature that we find in lunar charts4 ,if you will now glance at the northern 7lower7 #8horn' of the moon in the photograph you will notice1 near the terminator1 about two thirds of the way from the ,mare ,crisium to the end of the horn1 a pair of ring plains1 or crater rings1 apparently almost touching one another4 ,they are ,atlas and ,hercules1 the latter being the smaller one on the right4 ,a darker oval below them near the bright edge of the moon is ,endymion40 8,that1 at least10 exclaimed my companion1 delighted1 8is a romantic and appropriate name6 ,i am enchanted to think that ,endymion has not been separated by your cold-hearted science from her who loved him so well40 8,but if you should look at ,endymion with a telescope you would wonder what the moon could find in him to admire4 ,he has been turned into a huge1 broken-walled ring plain4 ,you will observe that the other1 the southern or upper horn of the moon in the photograph1 appears extraordinarily roughened4 ,it is completely pitted with craters and rings4 ,there are so many of them1 and they are so entangled1 that ,i shall not undertake to indicate them by their individual names1 especially as there is none among them of the very first importance4 ,if1 however1 you will bring your attention back to the ,mare ,nectaris ,i shall be able to point out to you a very extraordinary object1 which lies just on the border between day and night here1 but will be seen in the next photograph that we examine1 in full morning light4 ,the object that ,i mean is a ring on the right-hand edge of the ,mare ,nectaris4 ,its eastern wall and the top of its central peak are brightly illuminated by the rays of the rising sun2 while beyond it1 to the eastward1 everything1 with the exception of the tips of one or two high peaks1 is steeped in night4 ,this is one of the mightiest volcanic formations that the moon contains4 ,its name is ,theophilus4 ,to see it and certain gigantic neighbors that it has1 fully displayed1 we shall turn1 after this glance at its first appearance1 to photograph ,no4 #d4 8,in this photograph the sunrise line on the moon has advanced so much farther eastward that the ,mare ,nectaris lies well within the illuminated part of the disk1 and ,theophilus has become the most conspicuous object of the kind in view4 ,you now observe that it does not stand alone1 but is linked1 so to speak1 with another similar ring on its southeastern side1 while still farther southward is a third less regular ring which seems to belong to the same group40 8,oh1 yes10 cried my companion1 8they certainly do seem to be connected4 ,they look like three links of an enormous broken chain dropped upon the moon40 8,the ring nearest to ,theophilus10 ,i continued1 8and whose northwestern side has been destroyed to give room for the full circle of the wall of ,theophilus1 is named ,cyrillus4 ,the other more distant one is ,catharina4 ,if you wish to become a little learned in the geography of the moon it is necessary that you should remember these names4 ,as to the objects that the names designate1 they are far too wonderful ever to be forgotten1 and it is impossible to confuse them with any other features of the lunar world4 ,there is a great deal of #8history' connected with these three enormous volcanic formations1 but ,i am going to reserve that for a while1 because by and by we shall examine a larger photograph of these same objects in which you will see their marvelous details displayed4 ,now let me direct your attention to the first chain of mountains that we have found upon the moon4 ,above ,catharina you will notice a thin1 crinkled line of light passing through a comparatively level district and ending at another ring4 ,it is a range of peaks and cliffs named the ,altai ,mountains4 ,they are of no great height1 and cannot be compared in magnificence with the lunar ,alps and the lunar ,apennines which we shall see in the photographs taken a few days later1 but they are nevertheless very interesting4 ,the ring mountain at which the ,altai range terminates is named ,piccolomini4 ,it is another marvelous object for telescopic study4 ,the incomplete ring1 with a dark interior1 which forms the southern corner of the ,mare ,nectaris1 resembling a semicircular bay1 is ,fracastorius4 ,it is a very curious object because close inspection reveals that the missing part of its ring has been submerged1 but is still faintly visible through the surface of the ,mare40 ,illustration3 ,,no4 #d4 ,,november #bd1 #aijc2 ,,moon',s ,,age #e4gd ,,days4 8,i suppose it cannot be water that has covered it1 since you have so often assured me that there is no water on the moon40 8,no1 it is not water1 but rock or sand or solidified lava1 or some kind of solid matter4 ,it looks as though the whole bed of the ,mare ,nectaris had welled up in one mighty convulsive outpouring of liquid lava1 which broke down the wall of ,fracastorius1 inundated the interior1 and then hardened like a floor of cement4 ,the probability that a catastrophe of the kind ,i have described has occurred here is heightened by the fact that the bed of the ,mare ,nectaris is concave1 sunken in the center1 as if it had broken and settled down #8like ice upon a pond4' ,scattered more or less all over its surface and particularly near its shores1 there are indications of this breaking down1 and of something that has been covered up40 8,to me it seems very mysterious10 said my friend1 8and very terrible also40 8,it is more or less mysterious to the astronomer likewise4 ,still1 geology shows that there have been somewhat similar occurrences on the earth4 ,if you will now direct your eyes to the lower 7northern7 part of the photograph you will notice some additional things that have come into view with the advance of the sunlight4 ,you observe that a vast somber region occupies the inner portion of the crescent below the center4 ,this consists of two immense plains1 one of which sends a large #8bay' as far south as the ring of ,theophilus1 where it is connected by a narrow #8strait' with the ,mare ,nectaris4 8,turning to photograph ,no4 #e we see the two plains to which ,i have referred more fully displayed4 ,the sun has now risen over their entire surface4 ,the upper one is the ,mare ,tranquillitatis1 #8,sea of ,tranquillity'2 and the lower one the ,mare ,serenitatis1 #8,sea of ,serenity4'0 8,i have always thought that astronomers must be happy persons10 said my companion1 with a smile1 8and these names are convincing40 ,illustration3 ,,no4 #e4 ,,july #a1 #aijc2 ,,moon',s ,,age #f4bd ,,days4 8,yes1 perhaps1 but then in bestowing the names they may have been transferring to the moon ideals of tranquillity and serenity which they did not find realized upon the earth4 ,i am not going to talk about these two #8seas' at present because they are better represented upon one of the large photographs which we shall examine later4 ,i prefer to direct your attention just now to some other things4 ,in the first place look once more at ,theophilus and its companion rings1 and observe how they maintain their preminence4 ,the entire surface of the moon to the eastward and southward is broken and heaped up with mountains1 craters1 and rings1 but nowhere do we see anything comparable with ,theophilus except1 perhaps1 far toward the south1 where near the inner border appear two still larger1 but less regular1 rings lying in line at a right angle to the terminator4 ,the one on the left is ,maurolycus1 and the other1 still half obscured by night1 is ,stfler40 8,the names of old astronomers1 ,i suppose40 8,yes1 astronomers sufficiently famous in their day1 but who would be virtually forgotten at the present time if their friend ,riccioli had not thus immortalized them4 ,you see it is a great piece of good fortune to have your name in the moon4 ,it is a kind of revenge for the neglect of future generations at home40 8,and it seems to me an equal good fortune to have had an admirer willing to set your name up in the moon40 8,surely4 ,but ,riccioli's own name is there also4 ,afterwards ,i shall show you his lunar monument1 a truly magnificent one4 ,permit me now to tell you that ,maurolycus is much greater in extent than any of the rings that we have yet seen4 ,not by any means so perfect in form as ,theophilus1 it covers a vast extent of surface1 as much as #aej miles across1 with an amazing mass of broken rings1 walls1 ramparts1 ridges and chasms4 ,some of its peaks are #ad1jjj or #ae1jjj feet in height4 ,it has a very lofty central mountain1 visible in the photograph1 and whose peak comes into view when the sun is rising long before the surroundings have been illuminated1 so that it resembles a star glowing amid the blackest night4 ,the neighbor of ,maurolycus1 ,stfler1 is equally extensive and almost equally wild and magnificent when the sunlight is leaping across it from pinnacle to pinnacle and ridge to ridge4 ,in this photograph1 however1 it is too near the terminator to be well seen4 ,we shall presently pass to photograph ,no4 #f1 where ,stfler appears in full light1 but before doing so let us glance at the northern part of the moon as here pictured4 ,close to the terminator1 below the grand oval form of the ,mare ,serenitatis1 you will perceive two rings1 one above the other4 ,they seem to be the complement of the other pair1 ,atlas and ,hercules1 which we looked at when the sun had recently risen upon them in another photograph1 and which now appear far off toward the west4 ,you observe that ,atlas and ,hercules lie upon an east and west line1 and the others upon a north and south line4 ,the northernmost one is named ,aristoteles1 and the other ,eudoxus4 ,they are situated near the edge of a plain called the ,mare ,frigoris1 #8,sea of ,cold1' thus named1 ,i suppose1 because it lies so far north4 ,aristoteles is about #fj miles in diameter1 and its immense wall is very high and splendidly terraced4 ,eudoxus1 equally deep1 is only #dj miles in diameter4 8,turning to photograph ,no4 #f1 taken when the moon was more than a day older than it was when ,no4 #e was made1 we have a striking example of the effect of libration in presenting the moon at perceptibly different angles to our line of sight at corresponding phases4 ,we have now arrived at ,first ,quarter1 and behold all the western half of the moon illuminated by the sun4 ,you will perceive that we now have in view1 simultaneously1 six of the great plains called #8seas1' namely1 the ,mare ,crisium1 the ,mare ,fcunditatis1 the ,mare ,nectaris1 the ,mare ,tranquillitatis1 the ,mare ,serenitatis1 and the ,mare ,frigoris1 while others are beginning to emerge out of night on the east4 ,maurolycus and ,stfler1 the pair of giant rings in the south1 are better seen than before because daylight has advanced farther across them4 ,in fact ,stfler now appears more imposing than its great neighbor1 and a smaller ring breaking the continuity of its wall on the western side is visible4 ,above these1 in the direction of the south pole of the moon1 and around the pole itself1 the surface is marvelously rough and broken4 ,it looks as if it would be impossible to find a level acre of ground in all that region4 ,the rings and craters are veritably innumerable4 ,it is the existence of these irregularities which causes the terminator to appear so crooked and broken4 ,at some places you perceive small bright points within the edge of the night half of the moon4 ,these1 of course1 are the summits of peaks1 which have just been touched by the sunlight while the surface all around them is still covered with darkness4 8,below ,stfler1 all along the terminator1 as far as the middle of the moon1 an irregular row of rings appears4 ,three of these bear some resemblance to the great group of which ,theophilus is the chief member4 ,they are1 counting from south toward north1 ,aliacensis1 ,werner1 and ,blanchinus4 ,below them two other much larger ones are conspicuous1 ,albategnius1 the more southerly1 and ,hipparchus4 ,these two are full of moon history4 ,albategnius1 the smaller1 is very deep and comparatively perfect in condition1 while ,hipparchus1 more than #ij miles across1 has been vividly described as a #8wreck and ruin1' its walls1 once possibly of great height1 being now low and broken1 and traversed with gaps and valleys1 while a great cleft exists crossing a part of the broad1 irregular floor4 ,it is probable that ,hipparchus is an older formation than ,albategnius40 ,illustration3 ,,no4 #f4 ,,november #bf1 #aijc2 ,,moon',s ,,age #g4ge ,,days4 8,pardon me10 interrupted my companion1 8but ,i must cry for mercy4 ,really1 these strange names escape from my mind as fast as you mention them4 ,is there not something a little more romantic in the moon--something to relieve the strain of all this nomenclature of words terminating in #8us1' and this frightful lunar geology80 8,yes10 ,i said1 8,i believe that on the other half of the moon1 which has not yet seen the sun rise1 we shall find something better to your taste4 ,but do not be too impatient4 ,reflect that these names represent very wonderful things visible to us in another world than ours1 things the knowledge of which has cost the lifelong labors of many gifted men1 and that will be remembered1 studied1 talked1 and written about centuries after we are dead4 ,fortunately for your powers of attention the eastern half of the moon1 upon which day will be seen gradually dawning in the next set of photographs1 has a general character quite different from that of the western half4 ,it contains the greatest ranges of lunar mountains1 yet upon the whole it is more level1 being covered to a great extent with broad plains1 in the midst and along the borders of which stand the most remarkable and interesting of all the lunar formations4 ,in and around some of them we shall search for the evidences which some astronomers think that they have found of life upon the moon40 8,oh1 that indeed will be interesting60 exclaimed my friend with reviving animation4 8,but10 ,i added1 8do not place your expectations too high4 ,keep your imagination under control1 try always to be just a little #8scientific' in your way of looking at things1 and then ,i believe you will not be disappointed40 8,oh1 please do not think that ,i have been disappointed10 she said deprecatingly4 8,but positively you must admit that #8,albategnius1' #8,aliacensis1' #8,blanchinus1' and #8,maurolycus1' are not precisely captivating4 ,remember that ,i have read little except poetry and romance1 and those histories that are full of stories40 8,you will find a deep vein of poetry and romance in the moon10 ,i replied1 8before we have finished1 and after you have reflected upon what we have seen and what we have been saying40 ,leaving the remaining photographs to be examined after lunch1 we now entered the house4 ---------------------------------------- -------------------------------- ,,ii ,,first ,,quarter ,,to ,,full ,,moon ---------------------------------------- -------------------------------- ,,ii ,,first ,,quarter ,,to ,,full ,,moon ,,notwithstanding the signs of impatience which my friend had manifested when we were passing1 in our review of the photographs1 from one lunar ring mountain to another1 all more or less similar in appearance and characteristics1 ,i was gratified to see that her mind was still attracted to the subject of the moon1 and during the lunch she1 of her own accord1 began to talk of it4 8,you have said so much about volcanic occurrences on the moon10 she remarked1 8that ,i wonder why you do not call those immense mountains #8volcanoes4' ,i observe that you always speak of them as #8rings1' or #8mountain rings1' or #8ring plains'2 while to me1 although to be sure ,i am no geologist and have perhaps no right to an opinion1 they seem plainly to be just huge volcanoes and nothing else40 8,your observation is quite correct10 ,i replied1 8as far as superficial appearance goes1 and ,i may add that these great rings are often called volcanoes4 ,if we apply the proper adjective and name them #8lunar volcanoes1' perhaps there can be no objection to the term4 ,but they are certainly widely different from our terrestrial volcanoes4 ,the difference is not in size alone1 although in that regard it is enormous4 ,there is a far more significant difference1 which you could hardly be expected to notice in a simple inspection of the photographs1 although it is evident when once pointed out4 ,i refer to the fact that what seem to be the craters of lunar volcanoes are not situated on the tops of mountains4 ,they are immense plains1 more or less irregular in surface1 and often having a peak or a group of peaks in the center1 while around these plains always extends a mountain ring1 steep on the inner side1 and having a gradual slope without4 ,but most significant fact of all1 the plains1 or floors inside the ring1 are almost invariably situated thousands of feet below the general level of the moon4 ,if the terrestrial volcanoes were formed on the plan of the lunar ones1 when we visit ,vesuvius1 instead of climbing up a mountain rising out of the midst of a plain and capped with a cone1 having a funnel-shaped crater in the center1 we should find before us a relatively low1 circular elevation1 on surmounting which there would appear on the inside of the circle a great basinlike hollow1 far below the level of the surrounding country4 ,in the center of this1 distant from the lofty encircling walls1 would be seen a conical hill with smoke and vapor issuing from a vent at its summit4 ,the top of this crater hill would be lower than the rim of the basin-shaped hollow1 so that the whole volcano with its immediate surroundings would be inclosed and shut off from the environing upper world by the sides of the basin4 ,while you finish your coffee ,i will make a sketch which may render this difference between lunar and terrestrial volcanoes evident at a glance40 ,illustration3 ,lunar ,volcano1 in ,section4 ,illustration3 ,terrestrial ,volcano1 in ,section4 ,accordingly1 after a few minutes1 ,i presented to her these two diagrams1 remarking that it should be borne in mind that the two sketches were not made on the same relative scale4 8,i was compelled10 ,i said1 8to change the true proportions in the section of the lunar volcano1 for if ,i had drawn them as they are in fact1 the width of the basin would have been enormous in proportion to its depth4 ,you will recall that ,i told you that such rings as ,albategnius and ,maurolycus are a hundred miles and even more in diameter1 while their depth does not exceed two or three miles4 ,it results from this necessary falsification of proportions in the sketch that the terrestrial volcano1 although so widely different in form1 appears comparable in magnitude with the lunar one4 ,but the fact is that you could take a dozen of the largest volcanic mountains on the earth and throw them into one of the great lunar rings without filling it40 8,i am the more astonished by what you say10 remarked my friend1 8because you have already told me that the moon is so much smaller than the earth4 ,how does it happen1 then1 that her volcanoes are so much larger8 ,i should think that in a little world all things would be small in proportion40 8,it is quite natural to think so10 ,i replied1 8until you reflect upon the consequences of the smaller force of gravitation on a small world4 ,i told you last evening that gravitation on the moon1 is only one sixth as powerful as it is on the earth1 and you will recall that one consequence which ,i pointed out was that you would weigh only twenty pounds if you were on the moon4 ,since the same reasoning applies to all objects in the lunar world1 it is clear that a similar force exerted there would be able to produce enormously greater effects1 as for instance in the formation of vast hollows or depressions1 by violent explosions1 the products of which would be thrown to immense distances4 ,some selenographers1 which is a term applied to those who study the features of the lunar world1 have suggested that in this cause alone is to be found the explanation of the giant lunar ring mountains4 ,at some remote period of the past1 according to them1 the volcanic forces of the moon reached a maximum of activity and energy4 ,the lava1 cinders1 ashes1 and other products of ejection1 were hurled to a height of scores of miles1 and when this fell back at a great distance from the centers of eruption these were piled up in huge rings1 fifty1 eighty1 or a hundred miles in diameter1 while the surface of the moon within the rings sank in consequence of the withdrawal of the material thus ejected4 ,to account for the existence of the central mountains so often found in the middle of the rings1 it has been suggested that at a much later period1 when the volcanic energy had become comparatively insignificant1 as a result of the cooling of the interior of the moon1 less violent explosions1 not greater than many that have occurred on the earth1 took place1 and by these the central peaks were formed40 8,you are going to think me too romantic1 or too imaginative1 again10 said my friend1 with a smile1 8but ,i cannot prevent myself from wondering what the inhabitants of the moon did and thought while all those marvelous things were happening40 8,i have not said that there were inhabitants of the moon40 8,no1 but you have confessed that there might have been inhabitants1 some time1 and ,i should like to know whether they were there when those terrible volcanoes were formed40 8,if they were10 ,i replied1 8they could not have survived such a universal upheaval as the surface of the moon has undergone4 ,you have seen in the photographs that the great rings and smaller craters are scattered thickly over the moon4 ,it is true that comparatively few are found in the level expanses called #8seas1' but if those regions were covered with water they could only have been inhabited by beings provided with gills and fins40 8,how long ago did these explosions occur80 8,i cannot tell you1 except that it must have been many ages in the past2 so long ago1 indeed1 that the whole course of human history seems but a day in comparison40 8,then10 said my friend with animation1 8there has been time enough since that dreadful period for inhabitants to develop upon the moon1 has there not80 8,yes1 time enough1 perhaps1 provided that sufficient water and air and other vital requisites remained after the exhaustion of the volcanic energies40 8,oh1 let us say that they did remain4 ,i am eager to believe that the moon has not always been so desolate as she appears at present40 8,very well1 you are at liberty to believe that if you like4 ,no astronomer is likely positively to contradict you1 although he may smile a little incredulously4 ,besides1 as ,i have already told you1 there are certain rather inconclusive indications of some kind of life1 and of some kind of activity1 still on the moon40 8,please show them to me1 then1 or tell me about them4 ,perhaps ,i shall find them less inconclusive than you do40 8,everything in its turn10 ,i replied4 8,we shall come to the indications that ,i have spoken of after we resume the inspection of the photographs40 8,then ,i am ready to resume at once40 ,accordingly we returned to the table and the photographs under the pleasant shade of the elm4 ,taking up the photograph numbered #g1 ,i remarked that it exhibited the moon as it appears a little after ,first ,quarter2 that is to say1 a trifle more than half the face turned toward the earth is in the sunlight4 ,i called attention once more to the six 8seas10 which we had already remarked1 and to the continued conspicuousness of ,theophilus and its companions1 a little above the middle of the visible hemisphere4 8,you observe now10 ,i continued1 8how the rotundity of the lunar globe begins to manifest itself as the sunlight sweeps farther eastward4 ,the crescent shape is gone and the line between day and night begins to be bowed outward1 convexly4 ,the ,mare ,crisium is particularly well defined1 and also the diamond-shaped region called the ,palus ,somnii4 ,with the sun so nearly vertical above it1 the remarkable peak of ,proclus1 between the ,palus ,somnii and the ,mare ,crisium1 has become very brilliant4 ,in a telescope you would see it glowing almost like a star4 ,you observe also that several long1 straight1 bright rays proceed from it in several directions40 8,all the more reason1 it seems to me10 said my friend1 8why your unimaginative astronomer1 ,riccioli1 should have named it for some brilliant gem instead of attaching to so dazzling an object the prosaic designation of #8,proclus4'0 8,after all10 ,i replied1 8what's in a name80 ,now that you are familiar with the appearance of ,proclus1 its name will henceforth call up to your mind an image as brilliant as if it had been named #8,mount ,diamond' or #8,mount ,amethyst4'0 ,illustration3 ,,no4 #g4 ,,july #b1 #aijc2 ,,moon',s ,,age #g4bd ,,days4 8,pardon me10 said my friend1 8but it was not of names like those that ,i was thinking4 ,observe how he who named the neighboring ,palus ,somnii1 #8,marsh of a ,dream1' exhibited an exquisite delicacy of fancy4 ,it suggests something indefinitely strange1 romantic1 imaginative4 ,that unknown astronomer1 unknown at least to me1 put a little of himself1 a little of his inmost mind1 into the name1 and ,i thank him for it4 ,i shall never forget the #8,marsh of a ,dream' in the moon4 ,it will haunt my own dreams4 ,i shall be all my life seeking and never finding its meaning40 8,since you are in so poetic a mood10 ,i responded1 8,i rejoice that besides its bald facts1 its fireless volcanoes1 and its dried-up plains1 the moon possesses many things that can stir the imagination of the most sentimental observer4 ,but1 in order that we may not wander too far from the paths of science1 let me recall your attention to the photograph4 ,we have been going over ground already trodden by returning to the neighborhood of the ,mare ,crisium4 ,i shall now lead you back to the terminator1 where we shall find a little that is new4 ,still nearly hidden in night we perceive many great rings on which the sun is beginning to rise1 and four of the most important ranges of mountains are coming into view4 ,one of these1 on the southern border of the ,mare ,serenitatis1 is visible throughout its entire extent4 ,it forms a portion of the coquettish ornaments with which the ,moon ,maiden has decorated her hair1 as we shall see clearly in the next photograph4 ,this range is named the ,hmus mountains4 ,near its center1 quite at the edge of the #8sea1' is a bright crater ring1 one of the most conspicuous on the moon4 ,it is called ,menelaus40 8,menelaus80 exclaimed my friend4 8,ah1 then ,riccioli did not confine his favoritism to the astronomers and philosophers in putting their names in the moon4 ,menelaus1 if ,i remember my classical reading correctly1 was the husband of ,helen of ,troy40 8,yes1 the brother of ,agamemnon himself4 ,you must admit that ,riccioli occasionally felt his imagination a little awakened4 ,he was not altogether destitute of the spirit of poetry40 8,but did he also put ,helen in the moon80 8,i am sorry to say that he did not4 ,it would have been a very suitable abode for her4 ,however1 if you like1 you may recognize ,helen in the ,moon ,maiden herself40 8,thank you1 that will be1 indeed1 an unexpected pleasure40 8,meanwhile allow me to point out to you that there is a curious light streak1 very faintly shown in the photograph1 which crosses the ,mare ,serenitatis from ,menelaus to the opposite shore1 and reappears more distinctly1 on the lighter-colored plain toward the north4 ,this streak comes all the way from a great ring mountain named ,tycho in the southern part of the moon4 ,it is more than #b1jjj miles long1 and is one of the greatest mysteries of the lunar world4 ,tycho1 which lies just on the sunrise line1 is not well seen in this photograph4 ,it has a great number of these strange streaks or rays proceeding from it in all directions4 ,we shall study them in one of the photographs which are to come4 ,one word in regard to the plain north of the ,mare ,serenitatis of which ,i have just spoken4 ,it1 too1 has a name that is calculated to appeal to your lively imagination4 ,it is called the ,lacus ,somniorum1 which if my knowledge of ,latin is correct1 means #8,lake of the ,sleepers4'0 8,then your old friend ,riccioli certainly did not bestow the appellation40 8,no1 it was one of his more fanciful1 or1 if you prefer1 more poetical predecessors1 perhaps the same who imagined the #8,marsh of a ,dream4'0 8,oh1 that gives me another reason to think of him with admiration and gratitude4 ,he1 at least1 had a soul that rose above mere prosaic facts40 8,perhaps4 ,but do not think too lightly of the facts of the moon4 ,after all the human mind must base itself upon the solid ground of fact4 ,without that we should become mere dreamers1 and be suited only to inhabit your favorite #8,marsh4'0 8,the other mountain ranges of which ,i have spoken10 ,i continued1 8are faintly distinguishable eastward from the ,mare ,serenitatis4 ,they are the ,apennines1 the ,caucasus1 and the ,alps4 ,but perhaps we had better turn at once to photograph ,no4 #h where they are much more clearly seen1 because the sunrise there has advanced a couple of hundred miles farther east40 8,but1 dear me1 how slowly the sun rises on the moon6 ,was this photograph taken a day later than the other80 ,illustration3 ,,no4 #h4 ,,august #ca1 #aijc2 ,,moon',s ,,age #i4bb ,,days4 8,almost exactly two days later4 ,when it was made the moon was nearly nine and a quarter days old1 and its age at the time ,no4 #g was made was only seven and a quarter days4 ,but1 owing to the effects of libration1 an explanation of which ,i have put into a note for your private reading when you feel like it1 see p4 #eg1 footnote1 the difference of phase amounts to less than two days4 ,you are right1 however1 in remarking that sunrise is a very slow process on the moon4 ,it requires about two weeks to pass from the western side of the moon to the eastern side1 and both day and night at any point on the moon last about a fortnight4 ,this results from the fact that1 as ,i have told you1 the moon does not turn rapidly on its axis like our own globe1 but keeps always the same side directed toward the earth4 ,accordingly1 a lunar day and night are together about a month long40 8,and was it so when1 as ,i must persist in believing1 there were inhabitants on the moon80 8,probably1 although it may have been shorter then4 ,the consequences of these excessively long days and nights would be very serious to beings fashioned upon the terrestrial plan4 ,in the practical absence of an atmosphere the heat of the sun's rays1 pouring down without interruption and without the intervention of any clouds or vapors for fourteen days at a time1 must be simply overpowering4 ,and then1 during the equally long night that ensues1 the radiation into open space must quickly leave the surface of the moon exposed to the most frightful degree of cold1 comparable with the absolute zero of empty space60 8,but think1 what a merciless environment you are picturing for my inhabitants of the moon4 ,please do not forget that ,i insist that their comfort shall be considered40 8,oh1 as for that1 you know you were content a little while ago to relegate your inhabitants to a remote period in the past1 after the volcanic fury of the lunar world had ceased1 and before its present airless and waterless condition had supervened4 ,possibly at that time things were not so uncomfortable for them4 ,they may have had clouds to temper the sunshine1 rains to cool the days and dews the nights1 and shady parks like yours for philosophic and scientific contemplation40 8,do not forget the poets40 8,certainly not4 ,but is not the moon herself the very spirit of poetry8 ,what in nature is more poetical in its suggestions than the moon wading through fleecy clouds on a serene summer's night8 ,but pardon me1 we are forgetting my mountains1 upon which ,i insist as strongly as you do upon your inhabitants4 ,the mountains have this advantage that they are very real1 and no exercise of the imagination is required to bring them clearly before us4 ,in photograph ,no4 #h they are all visible4 ,the ,apennines1 the greatest of them1 start from the eastern end of the ,mare ,serenitatis1 and run in a slightly curved line southeastward1 a distance of about #dej miles4 ,they form the singular ornament which the ,moon ,maiden 7or shall we now call her ,helen of ,troy87 wears upon her forehead4 ,turn the photograph upside down so that the moon is presented as the naked eye sees it in the sky1 and you will find that1 although he aimed only to be scientifically exact and to exclude everything but the real facts1 ,mr4 ,wallace has produced an excellent picture of this wonderful face in the moon40 8,but what is that face80 8,it is humanity projected upon the moon4 ,it is a lesson on the powers of the imagination4 ,we perceive a certain collocation of mountains1 peaks1 and plains on the disk of the moon1 and our fancy sees in them a human likeness4 ,we should congratulate ourselves that we are able to do this4 ,it is a kind of proof of superiority4 ,many brute animals do not recognize even their own likenesses in a mirror1 much less in a picture4 ,but the ,moon ,maiden is perhaps as real as your inhabitants40 8,i am not prepared to confess that yet40 8,very well1 let us go on4 ,the lunar ,caucasus is the broader1 but shorter1 range of mountains at the northeastern corner of the ,mare ,serenitatis1 and the ,alps extend eastward from the ,caucasus to a conspicuous dark oval close to the terminator1 which is one of the most remarkable formations on the moon1 and which1 when we come to study it in one of the larger photographs1 will probably interest you deeply because it is one of the places where recent studies have discovered indications of what may possibly be some form of lunar life4 ,i wish now to direct your attention to the central and upper parts of the photograph4 ,running downward from the south1 a little west of the terminator1 you will perceive a double row of immense rings and ring plains4 ,they are not only remarkable individually1 but quite as remarkable for their juxtaposition in two long ranges4 ,among them1 in the westernmost row1 are three or four whose names you may remember--,maurolycus1 ,stfler1 ,aliacensis and ,werner4 ,still larger ones are included in the eastern row1 the largest of all being at the bottom4 ,it is rather a hexagon than a circle4 ,it is #aae miles in diameter1 and the flat plain inside the bordering mountains contains about #i1jjj square miles4 ,by close inspection you will perceive a small crater mountain near the northwestern side4 ,this immense walled plain is named ,ptolemus after a great astronomer of antiquity1 the author of the ,ptolemic system1 which treated the earth as the center of the universe4 8,still more interesting are the things visible farther south4 ,you cannot fail to remark a very beautiful ring1 a perfect circle1 brightly illuminated on the eastern side1 and having a bright point symmetrically placed in the exact center4 ,it is named ,tycho1 after another great astronomer1 and is generally regarded as the most perfect crater ring on the moon4 ,it is #ed miles in diameter1 and its walls are about #ag1jjj feet high on the inner side1 more than a thousand feet higher than ,mt4 ,blanc1 the giant of the terrestrial ,alps4 ,its central mountain is #e1jjj feet high4 ,the most remarkable thing about ,tycho is the vast system of #8rays' or bands which seem to shoot out from it in all directions1 traversing the surface of the moon1 north1 south1 east1 and west for hundreds of miles1 and never turning aside on account of any obstacle4 ,they lie straight across mountains1 valleys1 and plains4 ,we have already seen one of them1 the largest of all perhaps1 crossing the ,mare ,serenitatis and the ,lacus ,somniorum1 in the northern hemisphere of the moon4 ,nobody knows exactly what these rays mean or what they consist of4 ,we shall from this time on see them in all the photographs that we examine1 and later ,i shall have more to say about them1 and the speculations to which they have given rise4 8,about half way between ,tycho and the south pole of the moon1 you will see an enormous irregular plain1 with lofty broken walls1 interrupted by a number of crater rings4 ,several similar rings also appear in the interior of the plain4 ,if ,tycho is the most perfect in form of the lunar crater rings1 this great inclosure1 which is named ,clavius1 is the finest example of the walled valleys4 ,it is more than #adj miles across1 and covers an area of not less than #af1jjj square miles4 ,two of the rings within it1 which seem so small in comparison1 are #be miles across4 ,a smaller walled plain1 yet one of really immense size1 is seen half way between ,tycho and ,clavius1 and farther from the terminator than either of them4 ,this is ,maginus1 and it possesses the peculiarity that at full moon it practically disappears60 8,but how can that be possible8 ,i see nothing behind which it can be hidden40 8,it is the sunlight that hides it4 ,you must have noticed already that the rings and mountains are best seen when at no great distance from the terminator1 because there the sunlight strikes across them at a low angle1 and their shadows are thrown sharply upon the adjoining slopes and levels4 ,look at the western part of the moon in the photograph before us4 ,many of the huge rings and walled plains that were so striking in appearance when the sun was rising upon them are now barely visible4 ,langrenus and ,petavius1 for instance1 have become no more than whitish blotches1 and even ,theophilus is no longer conspicuous4 ,the reason is because when the sunlight falls vertically upon any part of the moon there are no shadows there1 and without shadows there can be no appearance of relief4 ,then the mightiest mountains are almost lost from sight in the universal glare4 ,the same thing would be apparent if you were suspended above the earth at a great height in a balloon and looking down upon the tops of the snowclad ,rockies4 ,without shadows serving to reveal their true character and to throw their outlines in silhouette upon the adjacent plains1 they would resemble only white spots and lines on the generally darker expanse of the continent4 ,but ,maginus is an extreme case4 ,owing to the relatively small elevation of its walls1 and their broken-up state1 and owing also1 probably1 to a similarity of color between the mountain ring and the inclosed plain1 when the light is vertical upon them1 as at the time of ,full ,moon1 they blend together and become barely distinguishable from one another1 and from the surrounding surface of the moon4 8,take now photograph ,no4 #i4 ,the age of the moon here is actually less than it was in the photograph that we last examined1 yet1 in consequence of libration1 which has caused the moon1 in effect1 to roll a little to one side1 the sunlight is farther advanced toward the east1 and we see many features of the lunar world that before had not yet emerged from night4 ,clavius you will notice is much more fully illuminated4 ,see how distinctly the shadow of its vast western wall is cast upon the floor of the valley within1 while the opposite eastern wall with its immense cliffs and precipices glows in full sunshine1 its shadow1 thrown toward the east1 blending with the darkness of night still covering that side of the moon4 ,southeast of ,tycho1 which is beautifully shown here1 two other great walled plains have come into view4 ,the uppermost of these is ,longomontanus and the other ,wilhelm ,i4 ,for a considerable distance below these 7toward the north7 the surface continues broken with rings and craters1 but at length these give place to a dark1 level expanse4 ,this is a part of the ,mare ,nubium1 or #8,sea of ,clouds4'0 8,not quite so romantic a name as some of the others10 remarked my friend1 8but still ,i think ,i can be sure that ,riccioli had nothing to do with the selection4 ,there is certainly something poetic in the idea of a sea of clouds40 8,it is a very beautiful region when examined with a telescope10 ,i continued1 8and its mountainous shores contain many interesting formations4 ,farther north1 you will observe1 near the terminator1 and apparently lying in the midst of the ,mare ,nubium1 a large ring1 as perfect in form as ,tycho itself4 ,this is a very famous object1 and it bears the name of the great astronomer ,copernicus1 who overthrew the ,ptolemic system and established in its place the true idea of the solar system1 namely1 that the sun is its center1 while the earth and the other planets revolve as satellites around him40 8,surely10 said my friend1 8,copernicus deserved to have his name placed in the moon1 and very conspicuously1 too40 ,illustration3 ,,no4 #i4 ,,august #b1 #aijc2 ,,moon',s ,,age #h4ig ,,days4 8,it could not have been made more conspicuous10 ,i replied1 8for the situation of the great ring mountain called ,copernicus1 in the midst of an immense level expanse1 makes it one of the most marked features of the lunar world4 ,copernicus is the subject of one of the larger photographs that we are going to examine later1 and ,i reserve a description of its peculiarities4 ,north of ,copernicus you will observe apparently a continuation of the ,mare ,nubium4 ,but it is really another #8sea' that we are looking upon there1 the ,mare ,imbrium1 #8,sea of ,rains4' ,the baylike projection that runs out into the bright highlands west of ,copernicus bears the name of the ,sinus ,medii1 #8,central ,gulf1' and the one just below it is the ,sinus stuum1 #8,gulf of ,heats1' which is certainly suggestive of dog days on the moon4 ,observe that the ,sinus stuum merges on the west with a dark1 oval area1 which is called the ,mare ,vaporum1 #8,sea of ,mists4' ,it is one of the darkest districts on the moon4 ,if you will now turn the photograph upside down you will find that the ,sinus ,medii constitutes the dark eye of the ,moon ,maiden1 while the ,sinus stuum and the ,mare ,vaporum form that portion of her hair which droops upon her forehead40 8,why not frankly call it frizzed80 8,because ,i feared that you would not consider that a sufficiently poetic term40 8,but ,i find poetry enough in the names #8,gulf of ,heats' and #8,sea of ,mists4' ,my admiration for the man who could think of such appellations continually increases40 8,then please reverse the photograph1 for we must not lose ourselves in dreams4 ,you will notice that the range of the lunar ,apennines runs between the ,mare ,vaporum and the ,sinus stuum on one side1 and the ,mare ,imbrium on the other4 ,the entire chain of the ,apennines is beautifully shown here4 ,they are exceedingly steep on the side facing the ,mare ,imbrium1 and gigantic peaks standing upon their long wall cast immense shadows over the #8sea4' ,their southwestern slopes are comparatively gentle1 rising gradually from the level of the ,mare ,vaporum4 ,at their upper or southern end1 in the direction of ,copernicus1 they suddenly terminate with a beautiful ring1 which is called ,eratosthenes4 ,this is a fine example of the disk or cup shape of the lunar volcano4 ,the bottom of ,eratosthenes lies #h1jjj feet below the level of the surrounding ,mare1 while peaks on its wall are as much as #ae1jjj or #af1jjj feet in height4 ,between the lower end of the ,apennines and the upper end of the ,caucasus ,mountains a strait opens a broad1 level way between the ,mare ,imbrium and the ,mare ,serenitatis4 ,on one of the large photographs these two #8seas' and the strait connecting them are represented in all their picturesque details1 as you will see when we come to study them4 ,i promise you at that time a free rein to your imagination and plenty of room for its flights4 ,on the northern border of the ,mare ,imbrium and close to the terminator we see once more the remarkable oval valley to which ,i referred when pointing out the lunar ,alps1 and which bears the name of ,plato4 ,i call your attention to it and also1 again1 to ,copernicus1 in order that you may compare their appearance here with that which they present in the next photograph1 taken when the moon's age was eleven and three-quarter days40 ,illustration3 ,,no4 #aj4 ,,november #cj1 #aijc2 ,,moon',s ,,age #aa4gh ,,days4 ,we hereupon turned to photograph ,no4 #aj4 8,now10 ,i continued1 8observe the difference that some two days' advance of the sunlight has produced4 ,plato is far within the illuminated part of the disk1 and it looks darker than before4 ,copernicus1 on the other hand1 which appeared as a sharp ring with one border dark when it was near the sunrise line1 has now become a round1 white spot1 somewhat darker in the center1 with a great grayish splatter surrounding it upon the surface of the ,mare4 ,in the meantime1 over nearly the whole extent of the ,mare ,imbrium the sun has risen and two other mares have made their appearance1 one of which1 extending across half the width of the eastern hemisphere1 might be called the ,pacific ,ocean of the moon1 if it had any water4 ,it is named the ,oceanus ,procellarum1 the #8,ocean of ,tempests1' while at its southern extremity a very dark nearly circular expanse1 inclosed with mountains1 bears the name of the ,mare ,humorum1 #8,sea of ,humors4'0 8,evidently the astronomer who bestowed that name was not in a joking mood else he would surely have called it the #8,sea of ,humor4'0 8,no1 apparently he was in deep earnest4 ,but what kind of humors he was thinking of ,i cannot tell4 ,perhaps the name occurred to him because the ,mare ,humorum is the darkest of all the great levels on the moon4 ,it is very conspicuous to the naked eye at ,full ,moon4 ,you will perceive that ,tycho has now become the most prominent of all the rings on the moon4 ,it will maintain this distinction and continue to gain in conspicuousness up to the time of ,full ,moon4 ,seen as we now see it1 ,tycho manifestly merits the appellation sometimes bestowed upon it of the #8metropolitan crater of the moon4' ,notice how bright the mysterious bands radiating from it have become4 ,the higher the sun rises upon them the more brilliantly they glow1 almost as if they were streaks of new-fallen snow4 ,they spread over the whole of the southwestern quarter of the moon1 hiding rings and mountains with their brightness4 ,one very notable ray runs down into the ,mare ,nubium1 and a fainter one parallel with it produces the semblance of a long1 walled way4 8,the ,south ,pole of the moon lies in the midst of a marvelously upheaved and tumbled region1 where one huge ring is seen breaking into another on every hand4 ,one of these rings1 named ,newton--it lies just on the upper edge of the disk1 south of ,clavius--surrounds the deepest known depression on the moon4 ,its bottom sinks to a depth of #bd1jjj feet below the highest point on the wall4 ,this gigantic hole is so profound that1 situated where it is1 close to the pole1 where the sun can never rise very high1 its depths remain forever buried in night4 ,it is the very ideal of a dungeon1 for if you were imprisoned at the bottom you would never see either the sun or the earth40 8,you make me shudder6 ,truly1 after all1 the moon appears to be a world filled with dreadful things4 ,who would ever imagine it1 seeing how serene and beautiful she is in a calm night80 8,yet is there not a kind of beauty even in those things1 like the abyss of ,newton1 which appall you only when you know the real facts about them8 ,there is a certain grace in their shapes and outlines1 and a great attraction for the eye in their contrasts of light and shadow4 ,it is the same sort of attraction which we find in such terrestrial scenes as the ,yosemite ,valley viewed from ,inspiration ,point1 or the awful depths and chasms of the ,grand ,caon of the ,colorado4 ,the presence of man and his works is not always essential in order to fix our attention upon the wonders of nature4 ,their very grandeur exalts us until we forget our little race and its ephemeral achievements40 8,still1 ,i hope that you will show me something on the moon less awe-inspiring and suited to awaken more quiet thoughts1 and especially to reassure me concerning my lunarians1 as ,i suppose you would call them40 8,you shall not be kept long in expectation4 ,turn your eyes once more to the ,mare ,imbrium4 ,you will observe that its northern shore consists of a series of curves1 each terminating with a promontory projecting into the sea4 ,when looking at it ,i am often reminded of an entrancing view which ,i once enjoyed from the summit of ,mt4 ,etna over the island of ,sicily4 ,from that great elevation nearly the whole eastern and southeastern coast of the island was visible as upon a map4 ,the indented shore stretched away in long1 graceful curves1 where the blue ,mediterranean contrasted sharply with the yellow sands1 and the eye1 wandering from ,catania to ,syracuse1 was enchanted with the beauty of those geometric lines4 ,but the winding coast of the ,mare ,imbrium is far longer than the shores of ,sicily1 and the mountains and cliffs bordering it are more wonderful than any corresponding scenes on the earth4 ,i wish1 particularly1 to have you look at the easternmost of the indentations on the northern side of the mare4 ,it bears a designation that must surely please your imagination4 ,it is the ,sinus ,iridum1 #8,gulf or ,bay of ,rainbows4'0 8,i recognize the work of my old friend the unknown astronomer4 ,verily he had a poetic soul6 ,and he has written his poem on the chart of the moon1 for those to read who can40 8,it is a charming landscape that the telescope reveals there10 ,i said1 8even though no rainbows are visible40 8,but you will not deny that they may once have spanned that bay and its shores with their exquisite arches80 8,no1 ,i shall not deny so pleasing a possibility4 ,i will only say that it lies beyond the ken1 and even outside the field1 of science40 8,then ,i regard it as fortunate that he was not too exclusive in his devotion to science1 for then he could never have seen the rainbows with the eye of fancy1 and your charts would not have been adorned with so delightful a name40 8,let me tell you about this bay or gulf10 ,i said1 tapping the photograph to recall her from her reverie4 8,you observe that it terminates at each end with a promontory4 ,that at the western end is named ,laplace1 and the other ,heraclides4 ,the latter is the more picturesque4 ,if ever you have an opportunity to see the moon with a good telescope do not fail to look at the promontory of ,heraclides1 for if you are fortunate in the choice of the time of observation when the setting sun is throwing its shadow over the adjoining #8bay1' you will find that the serrated outlines of the promontory represent1 in a very striking manner1 the profile of a woman1 more sharply defined than the face of our familiar ,moon ,maiden1 but a mere miniature in relative size4 ,the shores of the ,sinus ,iridum are bordered with high cliffs1 behind which rise the peaks of a mighty mountain mass4 ,just back of the center of the great bowed shore of the #8bay' appears1 in the photograph1 a small1 bright crater ring4 ,this bears the name of ,bianchini4 ,it is a lunar volcano1 #ah miles in diameter1 rising out of the midst of many ranges of nearly parallel hills and mountains1 the general direction of which corresponds with that of the shore of the #8bay4' ,if there is any place on the moon where one is tempted to think that the scenes of a living world might once have been witnessed it is the ,sinus ,iridum and its neighborhood4 ,its latitude is between #dj and #ej north1 corresponding with the most thickly populated zone of our own globe4 ,the surface of the #8bay'--once its bottom1 if we admit that it was ever filled with water--is gently undulating1 with winding ridges that suggest the action of tides and currents in sweeping to and fro deposits of sand and gravel1 and piling them in long rows of bars and shallows4 ,one can hardly help picturing in the mind's eye waves breaking on the curving beach and dashing against the projecting rocks of the promontories2 a white city seated just at the center of the shore of the #8bay1' near ,bianchini1 like ,naples at the feet of ,vesuvius2 a rich vegetation covering the slopes of the mountain valleys1 and romantic sails dotting the #8bay' and the neighboring #8sea4'0 8,i am very glad to observe10 interrupted my friend1 8that you are not hopelessly prejudiced against my opinion that the moon has not always been #8dead1' as you call it40 8,i am so far from it10 ,i replied1 8that ,i am half disposed to admit that she is not altogether dead even yet4 ,but it is my duty to keep you as close as possible to the known facts4 ,we shall see the ,mare ,imbrium and the neighborhood of the #8,bay of ,rainbows' again4 ,meanwhile1 suppose we turn to the next photograph of the series1 ,no4 #aa4 ,the age of the moon here is about thirteen days4 ,she is fast approaching the phase of ,full ,moon4 ,the first thing to which ,i would direct your attention now is the exceedingly brilliant point of light which has come into view near the terminator1 a little north of east where the ,mare ,imbrium merges into the ,oceanus ,procellarum4 ,in several ways this is the most noteworthy object on the moon4 ,it led the famous ,english astronomer1 ,sir ,william ,herschel1 to believe that he had seen an active volcano on our satellite4 ,he navely wrote in his notebook on a certain occasion3 #8,the volcano glows more brightly to-night6' ,yet it is no more active than the other craters and crater rings in the lunar world4 ,it is only extraordinarily1 almost incredibly brilliant--by far the most dazzling point on the moon4 ,it is a ring mountain1 and is named ,aristarchus4 ,it has a near neighbor1 barely visible in this photograph1 close by toward the east named ,herodotus4 ,herodotus is by no means remarkable for brilliancy4 ,the central peak and a part of the floor and the east wall of ,aristarchus consist of some material--nobody can tell what it is--which gleams in the sunlight1 ,i had almost said like diamonds1 although that would be an exaggeration4 ,there are three or four other crater rings on the moon1 including ,proclus1 which are also very brilliant1 but not one of them can be regarded as a rival of ,aristarchus4 ,its power of reflection is so great that it is even visible with a telescope in the lunar night1 when the only light of any consequence that reaches it is that sent from the earth4 ,it was1 indeed1 this fact which misled ,herschel4 ,he saw ,aristarchus shining on the night side of the moon1 and naturally thought that only the fires of an active volcano could have rendered it thus visible40 ,illustration3 ,,no4 #aa4 ,,december #a1 #aijc2 ,,moon',s ,,age #ab4ih ,,days4 8,and are you sure that he was mistaken80 8,positively4 ,there is no fire in ,aristarchus1 and has been none for ages40 8,but why do not astronomers undertake to find out what it is that makes ,aristarchus so brilliant1 then80 8,they have almost no data to go upon4 ,you should be informed that even the greatest telescopes1 with their highest powers1 are unable to bring the moon within less than an apparent distance of say forty miles4 ,at such a distance it is manifestly impossible to tell of what a lunar formation consists4 ,we cannot analyze the moon with the spectroscope as we can the sun and the stars1 because she does not shine with her own inherent light4 ,we can only infer that a large part of the substance of ,aristarchus consists of something which reflects a very great proportion of the light that falls upon it4 ,if a mountain on the earth were composed of a vast mass of crystals1 or of bare polished metal1 we might expect it to present1 when seen from the moon1 some such appearance as we notice when we look at ,aristarchus4 8,in this photograph the ,sinus ,iridum1 having the sun higher above it1 is more brilliantly illuminated than in ,no4 #aj4 ,particularly you will notice the brightness of the line of cliffs along its eastern curve1 terminating at the promontory of ,heraclides40 8,that is the promontory which presents the profile of a woman's face1 if ,i recall correctly what you told me40 8,yes4 ,please observe also that the oval of ,plato is as dark as ever1 while ,copernicus has1 if possible1 increased in brightness1 and the great splatter of broken rays around it seems to have extended farther over the surrounding maria4 ,almost directly east of ,copernicus1 in the ,oceanus ,procellarum1 appears a much smaller crater ring1 ,kepler1 which resembles a miniature of ,copernicus because it1 too1 is encircled with a kind of corona of short1 bright rays4 ,copernicus1 ,kepler1 and ,aristarchus mark the corners of a large triangle4 ,speaking of rays recalls us to ,tycho4 ,you will see that1 as ,i told you1 this wonderful formation grows in relative prominence when the period of ,full ,moon approaches4 ,its ringed wall and central mountain are obscured by their own brilliance1 while the gigantic system of bright bands1 or rays1 which have their center of origin at ,tycho1 is gradually becoming the master feature of the bright part of the moon4 8,i have told you that the ,mare ,humorum1 which is very sharply defined in the picture before us1 is the darkest of all the level areas that go under the name of #8seas4' ,it is not1 however1 the darkest spot on the moon4 ,there are several places where the surface appears1 at times1 much duskier than in any part of the ,mare ,humorum4 ,three or four of these are clearly discernible in this photograph4 ,they lie westward from ,copernicus in the ,sinus ,medii1 the ,sinus stuum1 and the ,mare ,vaporum4 ,their dusky hue strikes the eye at once4 ,they give the impression of sink holes4 ,no special name is attached to them1 but they must have been evident to the first observers1 with the smallest telescopes1 and it is rather surprising they should have escaped special designation on the lunar charts4 ,a fact which will especially interest you is that some observers look upon these and other dusky areas on the moon as being1 possibly1 indications of the existence of some kind of vegetation there40 8,but if there is vegetation there may be other kinds of life also1 may there not80 8,ah1 ,i have not said positively that there is vegetation1 but if there is then your conclusion as to other life may be correct4 ,glance next at the upper part of the disk along the terminator4 ,two or three broad oval rings have come into view there4 ,the largest of these with its long eastern wall lying exactly on the line between day and night is an extremely interesting formation1 bearing the name of ,schickard4 ,the plain within the ring is almost large enough to have been called a #8sea' or at least a #8lake4' ,it is about #acd miles in diameter1 and is in reality much more nearly circular than it appears to be4 ,like all similar formations situated near the #8limb' of the moon1 by which we mean the edge as viewed from the earth1 it is greatly foreshortened by perspective4 ,the scale of the photograph is1 unfortunately1 not large enough to reveal an unique thing in the immediate neighborhood of ,schickard1 toward the southeast4 ,i refer to what1 as far as its telescopic appearance goes1 might be described as an enormous bubble--a bubble #ed miles in diameter4 ,unlike the other formations the surface of this singular ring is elevated above the general level of the moon4 ,when we come to examine it in detail it hardly answers1 perhaps1 to my designation of a bubble1 since the edges are a little higher than the center1 giving it the form of a shallow dish4 ,if we could visit it we should find on approaching that we were climbing the slopes of what would seem to be a chain of low mountains1 and on reaching the summit we should see before us an elevated circular plain1 sinking gradually toward the middle4 ,filled with water it would form a shallow lake lying on the top of a broad1 flat mountain4 ,there is nothing else quite like it on the moon and certainly nothing on the earth40 8,it must have been a great curiosity in the days when the moon was inhabited1 and ,i suppose that scientific #8lunarians' organized expeditions to explore it40 8,perhaps1 if you choose to regard it in that way4 ,now look again at the ,mare ,humorum4 ,you perceive that its eastern side is lined with mountains and crater rings1 while near the center of the northern border there is a conspicuous ring with a bright line running from the southern edge to the center4 ,this is one of the most beautiful of lunar formations1 and is named ,gassendi4 ,it is a favorite object for those who study the moon with telescopes on account of the great variety and singularity of the details visible within the ring4 ,when you become a selenographer and possess your own telescope you will find few things more interesting to study than ,gassendi4 8,next let us take up photograph ,no4 #ab4 ,here the moon is once more a little #8older' than before1 and the sunrise line has again advanced a little eastward4 ,this advance does not appear so rapid when the terminator is near the moon's limb1 because1 on account of the rounding away of the lunar globe1 the illuminated surface is foreshortened from our point of view on the earth4 ,in this photograph you perceive that the wonderful shining mountain ,aristarchus has become even brighter than it was before1 or at least it is more conspicuous on account of the appearance of what seems to be a short ray shooting out from it in a southeasterly direction4 ,there is also a light spot just below it which is caused by a little mountain group called the ,harbinger ,mountains4 ,the bright ray connects ,aristarchus with its neighbor ,herodotus1 of which ,i spoke a little while ago4 ,there is a very remarkable feature of the moon here1 not shown in the photograph1 but to which ,i must briefly refer4 ,it is an enormous cleft1 or crack1 or1 if you please1 caon1 which starts from ,herodotus1 whose northern wall seems to have been broken through to give passage to it1 and goes winding across the surface of the ,oceanus ,procellarum with several sharp turns and angles for a total distance of nearly a hundred miles4 ,what produced this remarkable chasm on the moon it is difficult to say4 ,some have suggested that it may once have been the bed of a river1 but there are many serious objections to that view4 ,nevertheless1 there seems to be little doubt that if we were to visit the moon we should find1 in many ways1 a striking resemblance between this prodigious caon and that of the ,colorado ,river40 8,and are not all these things so ancient1 as far as you can tell1 that1 like the terrible volcanic rings1 they might have been formed before the appearance of inhabitants upon the moon80 ,illustration3 ,,no4 #ab4 ,,september #d1 #aijc2 ,,moon',s ,,age #ac4bg ,,days4 8,they certainly seem to be very ancient1 and ,i cannot deny the possibility of what you say40 8,very well1 then1 ,i1 for my part1 am convinced that curious eyes1 filled with the light of intelligence1 have peered down from the verge of that chasm into its fearful depths4 ,if you will not permit me this flight of imagination ,i shall refuse to take any further interest in the moon40 8,oh1 ,i should not think of refusing4 ,imagine what you will1 and draw your own inferences1 only remembering that they are not supported by ascertained facts1 and probably never will be4 ,yet for all that they may have an element of truth40 8,pardon me for saying that your astronomical science1 as far as it concerns the moon at least1 does not seem to me quite satisfying4 ,you are not bold enough in drawing conclusions40 8,on the contrary many astronomers think that some of their brethren are altogether too bold in that respect4 ,however1 it must be freely confessed that astronomical science1 except perhaps in its mathematics1 is not satisfying even to those who have created it4 ,nobody would rejoice more sincerely than the astronomer at the discovery of evidence of the former1 or even the present1 habitability of the moon4 ,it is surely a great disappointment that we have not been able to settle so apparently simple a question in regard to our nearest neighbor in the sky40 8,then if ,i were a multimillionaire ,i should certainly devote several of my millions to the construction of a telescope great and powerful enough to reveal so interesting a secret40 8,with your great telescope you could probably render possible many discoveries at present beyond our reach4 ,but the mightiest telescope that you could make would enable no one to see inhabitants on the moon1 even if they existed40 8,not if it magnified the moon a million times80 8,no1 for optical imperfections and the disturbances to clear vision produced by our atmosphere would absolutely prohibit the use of any such magnification4 ,and even supposing that one could use a magnifying power of #a1jjj1jjj diameters in viewing the moon1 how near do you think that would place us to the lunar surface8 ,it would still appear to be more than a quarter of a mile away40 8,that is not much4 ,i am sure ,i can see people at that distance40 8,oh1 yes1 but the distinctness of view would be nothing like so great as if you were looking at the same objects on the earth4 ,still1 if we could obviate the atmospheric and other difficulties1 a magnifying power of one million would certainly enable us to discover the works of the moon's inhabitants--their houses1 their fields1 their plantations1 their great establishments of art and industry4 ,but ,i assure you that a telescope of such power is a mere dream4 ,it could never be constructed without some fundamentally new and unheard-of discovery in optics4 ,we shall do better to turn once more to our photographs which1 at least1 have no deceptions4 ,dropping ,no4 #ab1 we shall take up ,no4 #ac1 which brings us practically to the ,full ,moon phase4 ,the moon's age at the time this photograph was made was nearly fourteen and one-half days4 ,you see that its whole eastward face is now lying in the sunlight4 ,the march of day across its surface has been completed1 and on the western edge of the moon the sun is about to set1 while on the eastern edge it is just rising4 ,among the new things that have come into view is a conspicuous dark oval1 shaped like ,plato1 but very much larger1 near the eastern edge4 ,this is a walled plain named ,grimaldi1 and it enjoys the distinction of being the darkest on the moon4 ,near it on the northeast and consequently closer to the limb is another walled plain1 which ,i promised some time ago to point out to you because it bears the name of the astronomer ,riccioli1 the great bestower of names on the moon1 and upon whose lack of imagination you have so severely commented4 ,but1 as you have already learned1 the time of ,full ,moon is not the best for studying the mountains and rings1 because then the light strikes too nearly vertical upon them and they cast no shadows4 ,but it is the best time for seeing the broad general features of the lunar surface4 ,turn the picture upside down again1 thus bringing the disk into its natural position as seen with the naked eye1 and this photograph shows the moon very much as it appears with a small pocket telescope1 or with a powerful binocular4 ,the new prism binoculars that have come into use within the past few years are excellent for general views of the moon4 ,their defining powers are superb1 and one who has never seen the moon with such a glass is always greatly surprised and delighted with the view which it affords4 ,you see now that ,tycho forms a blazing brooch1 resting on the ,maiden's neck1 while its rays extend across her profile1 and the long one lying over the ,mare ,serenitatis bears some resemblance to a pin displayed in her hair1 with the crater ring1 ,menelaus1 glittering at its lower end4 ,the other bright point1 to the left of ,menelaus 7we will henceforth keep the picture reversed71 is a ring mountain named ,manilius4 ,after the detailed study which we have given to the various #8seas' and formations you should be able to recognize them with the picture in this position1 and ,i wish that you should do so because1 as ,i have just remarked1 this is the position of the ,full ,moon as it is always seen with the naked eye or with a simple binocular1 for the latter does not reverse it1 as does a telescope4 ,the western edge is now at the right hand1 and the north at the top4 ,all the mares are clearly visible4 ,on the right the ,mare ,crisium1 the ,mare ,fcunditatis1 the ,mare ,nectaris and the ,mare ,tranquillitatis2 in the center1 above1 the ,mare ,serenitatis2 on the left the ,mare ,imbrium1 the ,mare ,vaporum1 the ,mare ,nubium1 the ,mare ,humorum1 and the ,oceanus ,procellarum4 ,the two bright spots on the right1 lower than the ,mare ,fcunditatis1 are ,petavius and a neighboring ring4 ,vendelinus forms a less brilliant spot at the western edge of an extension of the ,mare ,fcunditatis1 and ,langrenus is distinctly seen on the western shore of the main body of that mare4 ,proclus and the remarkable diamond of the #8,marsh of a ,dream' are very plain just under the large oval of the ,mare ,crisium4 ,the mountains and cliffs encircling the ,mare ,imbrium on the west1 north1 and east you will recognize at a glance4 ,the dark ,plato is conspicuous in the lighter mountainous area north of this #8sea1' and the semicircle of the #8,bay of ,rainbows' is sharply defined4 ,farther north is the long1 dark ,mare ,frigoris1 whose eastern end merges into the broad ,oceanus ,procellarum4 ,aristarchus appears as a very bright point in this #8ocean1' and far to the right of ,aristarchus1 toward the center of the disk1 ,copernicus1 with its splatter of irregular rays1 is conspicuous4 ,following the eastern limb round toward the south we see again the dark oval of ,grimaldi1 beyond which the bright mountainous region broadens as we approach the ,south ,pole4 ,illustration3 ,,no4 #ac4 ,,september #e1 #aijc2 ,,moon',s ,,age #ad4dj ,,days4 8,there is just one other thing on which ,i should like to dwell a little while we have the ,full ,moon before us4 ,i have already referred to it once or twice--,i mean the system of bright rays or bands radiating from ,tycho4 ,these rays1 as ,i have told you1 are among the greatest mysteries of the moon4 ,their appearance is so singular and1 if ,i may so describe it1 unnatural1 that when the first photographs of the ,full ,moon were published1 some persons actually thought that they were being imposed upon4 ,they imagined that the photographer had indulged in a practical joke1 by photographing a peeled orange and dubbing it #8the moon4' ,the mysterious rays do not start from the central mountain of ,tycho1 nor even from the ring itself1 but from a considerable distance outside the ring4 ,nevertheless1 ,tycho is manifestly the center from which they arise4 ,it looks as though some irresistible force had been focused at that point--a force that split the moon along a hundred radiating lines4 ,this is1 in substance1 the theory of the ,english selenographer ,nasmyth4 ,he supposed that1 the lunar globe being burst by internal stress1 molten lava welled up and filled the cracks4 ,after solidifying this lava possessed a lighter color and greater reflecting power than its surroundings and thus gave rise to the appearance of long bands40 8,really1 your moon history seems to me to be made up of extremely tragical chapters4 ,but ,i am content as long as you put all these terrific events sufficiently far in the past to leave time for the moon to have enjoyed a different kind of history since they occurred40 8,but10 ,i said1 8even if ,i grant what you wish1 you must admit that the greatest tragedy of all succeeded40 8,what do you mean80 8,i mean simply that your imagined lunar age of gold1 when the moon was full of animated existences and beautiful scenes1 has also become a thing of the past2 and what geological cataclysm can be compared in tragic intensity with the disappearance of a world of life80 8,but that disappearance was gradual1 was it not80 8,very likely it was1 if it depended upon the slow withdrawal of the atmosphere and water40 8,good6 ,then again ,i am fairly well content1 for all things must have an end4 ,the most beautiful life finally merges into old age and death4 ,i think ,i have read that some of your savants predict that the earth will not always be a living world4 ,all that ,i ask is that you leave room somewhere in your lunar history for an age of life on the moon40 8,very well then4 ,as ,i have told you several times1 ,science does not positively forbid you to picture such an age if you will4 ,she only says that she cannot find the evidences of its existence4 ,still1 as we are going to see later1 there are those who think that they can perceive indications of some simple forms of life on the moon even now4 ,i will grant you that in the past these may have been more numerous and more highly organized40 ,by this time the afternoon had waned and the trees were lengthening their shadows upon the lawns of the park4 8,perhaps10 ,i said1 8we had better postpone an examination of the remaining photographs of the series exhibiting the moon's various phases until after dinner4 ,they will show very well in the light of the electric chandelier4 ,i have but a few words to add concerning the rays of ,tycho4 ,the opinion of ,nasmyth concerning their mode of origin has not been universally accepted4 ,prof4 ,william ,h4 ,pickering1 for instance1 has suggested that the rays are formed by some whitish deposit from the emanations blown out of comparatively minute craters lying in rows4 ,he supposes large quantities of gas and steam given forth from craters surrounding the rim of ,tycho1 and1 in consequence of these gases and vapors being absorbed and condensed in more distant regions1 a wind constantly blowing away from ,tycho and distributing the white deposit in windrows4 ,a similar explanation has been applied to the shorter and more irregular systems of rays surrounding ,copernicus1 and a few other ring mountains40 8,i prefer the ,nasmyth hypothesis10 said my friend1 as we rose and took the path to the house4 8,it is1 to be sure1 more gigantically tragic1 but then it is simpler and more easily comprehended40 ---------------------------------------- -------------------------------- ,,iii ,,full ,,moon ,,to ,,old ,,moon ---------------------------------------- -------------------------------- ,,iii ,,full ,,moon ,,to ,,old ,,moon ,,after dinner1 in the brilliantly lighted drawing-room1 we once more spread out the photographs on a table4 8,this time10 ,i said1 taking up ,no4 #ad1 8we are going to watch the advance of night over the moon4 ,before1 it was the march of sunrise that we followed4 ,both begin at the same place1 the western edge or limb of the moon4 ,comparing this photograph1 which was taken when the moon was about fifteen and two-third days old1 with ,no4 #ac1 taken when the moon's age was more than a day less1 you perceive1 at a glance1 wherein the chief difference lies4 ,in ,no4 #ac sunrise is just reaching the eastern limb2 in ,no4 #ad sunset has begun at the western limb4 ,having watched day sweep across the lunar world1 we shall now see night following on its track4 ,west of the ,mare ,crisium and the ,mare ,fcunditatis1 which ,i expect you to recognize on sight by this time1 darkness has already fallen1 and the edge of the moon in that direction is invisible4 ,the long1 cold night of a fortnight's duration has begun its reign there4 ,the setting sun illuminates the western wall of the ring mountain ,langrenus1 which you will remember was one of the first notable formations of the kind that we saw emerging in the lunar morning4 ,but then it was its eastern wall that was most conspicuous in the increasing sunlight4 ,for the selenographer the difference of aspect presented by the various objects of the lunar world when seen first under morning and then under evening illumination is extremely interesting and important4 ,many details not readily seen1 or not visible at all1 in the one case become conspicuous in the other4 ,but it is only close along the line where night is advancing that notable changes are to be seen4 ,over the general surface of the moon there is not yet any perceptible change1 because the sunshine still falls nearly vertical upon it4 ,tycho's rays are as conspicuous as ever4 ,aristarchus1 away over on the eastern side1 is1 if possible1 brighter than before1 and the three small dark ovals1 ,endymion a little west of the north 7or lower7 point1 ,plato at the edge of the ,mare ,imbrium1 and ,grimaldi near the bright eastern limb1 are all conspicuous40 ,illustration3 ,,no4 #ad4 ,,august #bf1 #aijd2 ,,moon',s ,,age #ae4fe ,,days4 8,but look60 exclaimed my friend1 putting her finger upon the photograph4 8,here is something that you have not mentioned at all4 ,i believe that ,i have made a discovery1 although you probably will not accept it as a scientific one4 ,i see here a dark woman in the moon40 8,i confess10 ,i replied1 8that ,i am not acquainted with her1 and do not even see her4 ,please point her out to me40 8,she appears in profile1 like the brilliant ,moon ,maiden1 but is not so much of a beauty4 ,in fact ,i begin to suspect that she is the #8,old ,woman in the ,moon1' that ,i have often heard of40 8,positively ,i do not see her40 8,then ,i will try to recall some of the names that you have been telling me in order to indicate where you should4 ,she faces west and occupies most of the eastern half of the disk4 ,her head is under ,tycho1 toward the northeast1 ,i suppose you would say4 ,the bright double ray that you pointed out in one of the preceding pictures lies across the top of her head and over her ear4 ,her face seems to be formed by a part of the ,mare ,nubium--you observe how well ,i have learned your selenographical terms--and her hooked nose is composed of a kind of bay1 projecting into the bright part below ,tycho4 ,her front hair is banged1 and the ,mare ,humorum constitutes her chignon4 ,she has a short neck1 and a humped back1 consisting of the ,oceanus ,procellarum4 ,copernicus resembles a starry badge that she wears on her breast1 and ,aristarchus glitters on the inner side of the elbow of her long arm4 ,the ,mare ,imbrium seems to be a sort of round1 bulky object that she carries on her knee1 and she appears to be gazing with intentness in the direction of the ,mare ,tranquillitatis40 8,ah1 yes10 ,i said1 laughing1 8,i see her plainly enough now4 ,i really cannot say that your discovery is likely to be recorded in astronomical annals1 but nevertheless ,i congratulate you upon having made it1 if only for the reason that henceforth you can never forget the names and locations of the lunar #8seas' and other objects that you have been compelled to remember in pointing out your #8dark woman4' ,in truth1 her features are almost as well marked as those of the ,moon ,maiden1 but you will hardly be able to find her again1 except in a photograph1 or with the aid of a telescope1 because you must recollect that this picture shows the moon reversed top for bottom as compared with her appearance to the naked eye1 or with an opera glass4 ,but please look again at the objects along the western edge1 for we are about to turn our attention to photograph ,no4 #ae in which this will be no longer visible4 ,you must say #8good-by1' or rather #8good night1' to the ,mare ,crisium and the ,mare ,fcunditatis2 for you will see them no more1 until another lunar day has dawned40 ,we next picked up photograph ,no4 #ae4 ,illustration3 ,,no4 #ae4 ,,august #bh1 #aijd2 ,,moon',s ,,age #ag4da ,,days4 8,here the age of the moon has increased to nearly seventeen and a half days4 ,the sunset line has advanced to the borders of the ,mare ,nectaris and the ,mare ,tranquillitatis4 ,toward the south a vast region which was very brilliant in the morning and midday light with the reflections from mountain slopes and the rays of ,tycho1 has passed under the curtain of night4 ,the great crater rings on the eastern border of the ,mare ,nectaris1 and thence upward to the ,south ,pole1 are beginning to reappear1 but with the shadows of their walls thrown in a direction opposite to that which they assumed before4 ,by a little close inspection you will recognize ,theophilus and its neighbors which were so conspicuous for many days while the sunrise was advancing1 but which have been almost concealed in the universal glare of the perpendicular sunshine since the ,full ,moon phase was approached4 ,on the ,mare ,tranquillitatis and the ,mare ,serenitatis it is late afternoon1 and your favorite #8,marsh of a ,dream' has become a true dreamland40 8,this oncoming of night10 said my friend1 8seems to me more imposing1 and more suggestive of mystery than was the advance of day40 8,surely it is4 ,do we not experience similar sensations when night silently creeps over the earth8 ,but it imparts a feeling of loneliness and desolation when we watch it swallowing up the barren mountains and plains of the lunar world that we do not experience in terrestrial life4 ,there are no cheerful interiors on the moon to which one can retreat when darkness hides the landscapes4 ,there is another thing about the lunar night to which ,i have made but scant reference thus far4 ,i mean it's more than ,arctic chill4 ,imagine yourself standing there in the midst of the broad plain of the ,mare ,tranquillitatis4 ,toward the east you would see the sun close to the horizon1 yet blazing bright and hot1 without clouds or mists to temper its rays4 ,the rocks or soil beneath your feet would perhaps be cold to the touch1 because the surface of the moon radiates away the heat very quickly1 but your face and hands would be almost scorched by the intense solar beams4 ,looking toward the west you would see the shining tips of mountains suddenly extinguished1 one after another1 and when the sharply defined edge of the advancing night passed over you it would be as if you had plunged into a cold bath4 ,in a little while1 if you remained motionless1 you would be frozen4 ,no clothing would suffice to keep you warm4 ,nothing that polar explorers have ever experienced can be likened to the cold of the lunar night4 ,only the apparatus of the laboratories for producing temperatures1 capable1 when combined with pressure1 of liquifying and solidifying the air itself1 can bring about upon the earth a lowering of temperature comparable with that which occurs during the lunar night40 8,but ,i do not exactly see why night should be so much colder on the moon than on the earth4 ,she is not farther from the sun40 8,no1 her average distance from the sun is the same as that of the earth4 ,the reason why her nights are so cold is to be found in the absence of an atmosphere like ours4 ,the air is the earth's blanket1 which serves a double purpose1 tempering the heat by day with its vapors and winds1 and keeping the earth warm at night by preventing the rapid radiation into space of the heat accumulated during the daylight hours4 ,if there is any atmosphere at all upon the moon--and ,i shall tell you by and by what has been learned on that subject--it is so rare as compared with ours that it can exercise very little effect upon the temperature of the lunar surface4 8,now1 look at the great range of the lunar ,apennines4 ,you will see that the eastern faces of these mountains are in the sunlight1 and they cast no shadows1 as they did in the lunar morning1 over the ,mare ,imbrium4 ,the same is true of the lunar ,caucasus1 and the lunar ,alps4 ,all of these mountains are very steep on the side facing the plains1 and that is the side presented sunward in the lunar afternoon4 ,by turning to photograph ,no4 #af1 we shall see this phenomenon more clearly displayed4 ,this photograph1 measured by the age of the moon when it was taken1 is more than a day older than the other1 but once again the effect of libration has1 in part1 counteracted for us the advance of the line of sunset4 ,still it has distinctly advanced4 ,you will observe that it has now passed completely across the ,mare ,nectaris1 and more than half across the ,mare ,tranquillitatis1 while only the mountain tops along the western edge of the ,mare ,serenitatis remain to indicate its outlines in that direction4 ,theophilus1 ,cyrillus1 and ,catharina1 on the eastern border of the ,mare ,nectaris1 have again become very conspicuous1 but this time in evening instead of morning light4 ,see how sharply the western wall of ,theophilus stands out against the darkness of night behind it1 and how its central peak glows in the setting sun while all the vast hollow beneath it is black4 ,the floors of ,cyrillus and ,catharina1 being less profoundly sunken1 are still illuminated4 ,below the ,mare ,serenitatis1 the twin rings1 ,aristoteles and ,eudoxus1 are very conspicuous1 and they show the same change of illumination as ,theophilus1 their western sides being strongly illuminated on their inner faces1 while the eastern walls cast shadows into the interior4 ,the mountainous character of the surface in the neighborhood of the ,north ,pole of the moon seems to be more clearly brought out in evening than in morning light4 ,in this picture the ,north ,polar ,region seems to be almost as much broken up with gigantic rings as is that surrounding the ,south ,pole4 ,in both cases1 you observe1 many of the rings are poised just on the edge of the lunar disk1 and their libration alternately swings them in or out of view40 ,illustration3 ,,no4 #af4 ,,august #bi1 #aijd2 ,,moon',s ,,age #ah4fb ,,days4 8,then the other side of the moon may not be very different from the side that is turned toward us40 8,in its general features ,i doubt if it is at all different4 ,there was once a theory1 which had considerable vogue1 that the side of the moon turned away from the earth presented a great contrast with its earthward side4 ,a ,german mathematician1 ,hansen1 drew conclusions1 which are no longer accepted1 as to the form of the moon4 ,he thought that the moon was elongated in the direction of the earth1 somewhat like an egg1 her center of figure being about thirty miles nearer to us than her center of gravity4 ,this1 if true1 would make the part of the lunar surface that we see lie at a great elevation as compared with the other part1 and the center of gravity being toward the other side would cause the atmosphere and water to gravitate in that direction40 8,what a pity that so interesting a theory should have been abandoned60 8,if interest were the only test of the value of a scientific theory knowledge would not advance very fast4 ,notice how this very photograph before us vindicates the true scientific attitude toward nature4 ,it records all the facts within its range1 and leaves the theories to us4 ,the features of your #8dark woman' are1 in their way1 as clearly marked in the photograph as is the range of the lunar ,apennines4 ,it is for us to recognize the essential difference between the interpretations which we choose to put upon these two phenomena4 ,giving play to fancy1 we see the figure of an old woman in the one case1 and employing our reason we find a chain of unmistakable mountains in the other40 8,but surely you do not mean to aver that science has no other business than that of recording facts40 8,by no means4 ,it is also the business of science to find hypotheses and to build up theories that will explain its facts and connect them together systematically1 according to some underlying law4 ,but as ,i have just intimated it is the mark of true science that it never retains a theory merely because it is interesting4 ,the truth is the only touchstone4 ,still1 even the most conscientious scientific investigator may be misled by his imagination4 ,his greatest virtue is that he never lets his fancies deceive him after he has recognized their false character4 ,point out your #8dark woman' to the child1 or the savage1 and it will be in vain afterward to explain that her profile is made up of plains and mountains4 ,the child and the savage are not scientific but imaginative1 and only after a long education will they abandon the apparent for the real4 8,i will ask you now to take up photograph ,no4 #ag4 ,the age of the moon here is twenty days4 ,comparing it with the last photograph we see that ,theophilus has disappeared1 although ,cyrillus and ,catharina1 being a little farther east1 are yet visible4 ,half of the ,mare ,serenitatis is buried in night1 and only a little of the eastern edge of the ,mare ,tranquillitatis remains visible4 ,aristoteles and ,eudoxus are now very close to the terminator1 and the shadows of their eastern walls are spreading farther over their floors4 ,aristarchus is very brilliant1 as it is still early afternoon on that part of the moon1 and the sunshine is intense4 ,observe that ,kepler1 the crater ring directly east of ,copernicus1 has become more conspicuous than we have seen it in any preceding photograph4 ,this is especially true of the system of bright rays surrounding it1 and it is due to the change of illumination4 ,in the southern part of the moon1 west of ,tycho1 you will now recognize many gigantic formations which we first saw when the sun was rising over them4 ,some of them are even more prominent in the sunset light4 ,among these is our old acquaintance ,maurolycus1 whose western wall is so brilliant that it resembles a tiny crescent moon4 ,the double row of broad1 dish-shaped walled plains along the central meridian has also become visible once more4 ,in fact the amount of delicate detail and the sharpness of the definition in these photographs are very remarkable4 ,observe the curious mottling of the #8seas4' ,it is in some of the differences of tint1 which correspond in telescopic views of the moon more or less closely with the varying shades in the photographs1 that some selenographers have thought they could detect evidences of the presence of vegetation on the moon4 ,we shall talk about that more in detail another time4 ,it is sufficient just now to notice that the beds of the mares are by no means uniform either in tint or in level4 ,all of them are more or less #8rolling1' like many of our prairies1 and often winding chains of hills and huge cracklike ravines are visible in them4 ,in this photograph the amount of detail shown in the ,mare ,imbrium is particularly striking4 ,notice how some of the crinkled rays from ,copernicus extend almost to the center of the #8sea1' and how in front of the precipitous base of the ,apennine range the lighter-colored ground1 with three prominent ring plains in it1 presents the appearance of shallows4 ,lying off the shore south of ,plato and the ,alps a number of isolated mountain peaks are seen1 mere white specks on the gray background4 ,the undulating character of the #8bottom' of the #8,bay of ,rainbows' is also distinctly indicated4 ,by the way1 ,i should perhaps mention the names of the three rings lying off the front of the ,apennines1 for although they are among the most interesting on the moon they have hitherto escaped our special attention4 ,the largest of the three is ,archimedes1 the second in size is ,aristillus1 and the smallest is ,autolycus4 ,you will hear of them again when we come to the large photograph of the ,mare ,imbrium and the ,mare ,serenitatis4 ,illustration3 ,,no4 #ag4 ,,october #aj1 #aijc2 ,,moon',s ,,age #bj4jf ,,days4 8,let me now prepare you for an almost dramatic change in the appearance of some of the most conspicuous lunar features which will take place when we pass from this photograph to ,no4 #ah4 ,direct your attention particularly to the chain of the ,apennines4 ,in ,no4 #ag it lies very brilliant in the sunlight1 with its western slopes distinctly visible1 rising gradually from the shores of the ,mare ,serenitatis and the ,mare ,vaporum1 while the #8sea' along its eastern front is bright with day4 ,in ,no4 #ah the ,apennines have become simply a chain of illuminated mountain tips with comparative darkness all around them4 ,their western slopes are practically invisible1 the ,mare ,imbrium on the east has turned dark1 as if twilight had fallen over it--although as ,i have told you there is no twilight on the moon--and at its northern end the great range1 with only its summits illuminated1 projects like a row of electric lights far into the black night that has covered the plains beneath4 8,yet1 although the ,mare ,imbrium has turned so dark as to be barely visible over its western half1 the sun has by no means set upon it1 and the darkness is perhaps greater than it should1 theoretically1 be under the circumstances4 ,this phenomenon of the rapid darkening of the great lunar levels as the sun declines is one of the arguments that have been found to favor the hypothesis of the existence of vegetation4 ,if1 for the sake of discussion1 we admit the possibility of vegetation growing on the lunar plains1 it will be interesting once more to compare photographs ,nos4 #ag and #ah40 8,don't say that it is merely for the sake of a discussion10 interrupted my friend4 8,i shall be far more deeply interested if you will simply say that it may be true40 ,illustration3 ,,no4 #ah4 ,,september #bi1 #aijd2 ,,moon',s ,,age #bj4ej ,,days4 8,very well1 let us put it that way1 then4 ,as ,i was remarking1 if we again compare the two photographs1 keeping the vegetation hypothesis in view1 we may ascribe at least a part of the rapid darkening of the plain of the ,mare ,imbrium to a change in the color of the--what shall ,i say1 grass8--covering it40 8,good6 good60 exclaimed my friend1 clapping her hands4 8,just listen to him6 ,after gravely rebuking me so many times for my unscientific faith in the lunar inhabitants of a long past age1 now you are talking of #8grass' on the moon40 8,you are hardly fair10 ,i protested4 8,it is you who have just led me to make an admission which many astronomers would laugh at1 and you ought to support me with all the brilliance of your imagination when ,i try to picture a state of things so consistent with your predilections about the moon40 8,oh1 ,i do support you with all my heart60 she replied4 8,pray go on1 and tell me about the lunar grass40 8,not just at present10 ,i said4 8,we are going to take that subject up again1 and ,i may then succeed in convincing you that there is far more evidence for believing that vegetation exists on the moon in the present day than for believing that intellectual beings inhabited it at some unknown former period4 ,i should warn you1 too1 that ,i have been using the contrasts of light and darkness between these two successive photographs simply as an illustration of what occurs in visual telescopic views2 but that1 for some reason1 the lunar plains nearly always appear darker in photographs when contrasted with the mountainous regions than they do when viewed with the eye4 ,owing1 also1 to a variety of influences two successive photographs of the moon may differ in tone when the eye would detect no corresponding difference4 ,all this1 however1 does not invalidate what ,i have said about the lunar #8seas1' or plains1 darkening near sunset more rapidly than we should expect them to do1 as a simple result of the low angle at which the sunlight strikes them4 8,you will notice that the waning of day between photographs ,nos4 #ag and #ah has produced a remarkable change in the appearance of ,tycho4 ,since the ,full ,moon phase ,tycho has resembled a button rather than a volcanic crater1 but now it has once more assumed the form of a very beautiful ring with its central peak clearly shown1 its western wall1 bright and its eastern wall casting a broad1 black shadow4 ,most of the rays have now disappeared1 only two or three1 running over the eastern hemisphere1 remaining visible4 ,the immense walled plains near ,tycho have again become prominent1 ,maginus toward the southwest1 ,clavius toward the south1 and ,longomontanus toward the southeast being the most conspicuous4 ,clavius is always a wonderful object for the telescope1 but it is rather more interesting in the lunar morning than in the evening4 ,away over near the eastern limb1 where the sun is still high1 ,grimaldi shows its dark oval1 with a couple of mountain peaks on its western rampart shining brilliantly4 ,the small1 dark spot below it1 toward the east1 is in the walled plain1 ,riccioli4 ,the bright spot with starlike rays1 a long way south of ,grimaldi1 and east of the ,mare ,humorum1 is ,byrgius1 a walled plain near which exists a small system of bright streaks resembling those surrounding ,copernicus and ,kepler1 but much less extensive40 8,do you recall my expression of impatience this morning when you were giving me the names of a long string of crater rings80 said my friend1 smiling4 8,well1 ,i am now going to make a confession4 ,perhaps it is slightly of a penitential nature4 ,i find now that these names1 although they certainly are far from picturesque in most cases1 begin to interest me1 because1 ,i suppose1 ,i understand better the character and meaning of the things that they represent4 ,the ceaseless ,latin terminations no longer annoy me1 for ,i do not think of them1 but of the things themselves40 8,it is always so10 ,i replied1 8whenever one takes up a new study4 ,i know that you have dipped a little into botany1 and ,i am sure that the ,latin names which abound in that science must have repelled you at first4 ,but after a time1 when you had begun to recognize the beautiful flowers and the remarkable plants for which they stood1 you found that even these names assumed a new character and became interesting and memorable4 ,you will find it the same if you continue to study the moon4 ,the most stupid designations will derive interest from their applications40 8,yes1 that is no doubt true4 ,still1 ,i wish that ,riccioli had possessed a little more imagination40 8,be thankful1 then1 that he did not name the lunar #8seas' and #8bays4' ,you must now bid good night to your #8dark woman4' ,you observe that the ,mare ,nubium is beginning to fall under the shadow1 and that her features are growing indistinct4 ,if you will turn the photograph upside down you will find that the ,moon ,maiden has retired4 ,she belongs exclusively to the western hemisphere1 and it is only the eastern hemisphere of the moon that now remains visible to us1 for we are close to the phase of ,last ,quarter4 ,this is an aspect of the moon with which you may not be very familiar4 ,to see the moon at ,last ,quarter1 and particularly after she has passed that phase1 we must rise near midnight and devote the early morning hours to observation4 ,during these later phases1 however1 one may see the moon in the heavens during the daytime all through the forenoon and a part of the afternoon4 ,she is a very beautiful object then1 although few persons1 ,i fear1 ever take the trouble to look at her4 ,the lighter parts of her surface assume a silvery tint in the daylight1 and the dark plains seem suffused with a delicate blue from the surrounding sky4 ,exquisite views of the moon may then be obtained with a telescope4 ,the glare of reflected light from the mountains and crater rings1 which dazzles the eye at night1 is so reduced that the telescopic image becomes beautiful1 soft1 and pleasing4 ,the same principle has been very successfully applied in recent years to the study of the planet ,venus4 ,her atmosphere is so abundant1 in contrast to what we find on the moon1 that she is as blinding in a telescope as a ball of snow glittering in full sunshine2 but when seen in the daytime1 her features1 indistinct at the best1 may be more clearly discerned40 8,oh1 you interest me deeply6 ,if ,venus is supplied with such an abundance of air1 ,i suppose she is inhabited80 8,it is not exactly orthodox among those calling themselves astronomers to talk of inhabitants on the planets1 but ,i do not mind telling you privately that ,i think that ,venus is most likely a world filled with all kinds of animate existences4 ,our present business1 however1 is with the moon1 and ,i must recall your attention to the photographs4 ,we shall next take up ,no4 #ai4 ,here the crescent shape becomes again evident1 but reversed in position as compared with the crescent of the new and waxing moon4 ,only two of the #8seas' now remain completely in view--the ,mare ,humorum and the ,oceanus ,procellarum40 8,that term ,i think you have translated as the #8,ocean of ,tempests4' ,pray1 do you know any reason why it should have been thus named80 ,illustration3 ,,no4 #ai4 ,,august #af1 #aijc2 ,,moon',s ,,age #bc4ha ,,days4 8,there is not the slightest reason that ,i know of4 ,you must ascribe it to the vivid imagination of that old astronomer whom you so greatly admire4 ,i regret1 sometimes1 that he cannot be here to explain to you the thoughts that occupied his mind4 ,they must surely have been very captivating1 even though not very scientific4 ,remark that there are many of the features of the eastern part of the moon which we can now discern more clearly than in any of the preceding pictures4 ,beginning at the top we see the vast inclosure of ,longomontanus with the top of its encircling walls illuminated1 while the interior is all in deep shadow4 ,its western rampart projects into the night and seems detached from the main body of the moon4 ,along the terminator below ,longomontanus1 what appears to be another immense walled plain presents a similar aspect4 ,this1 however1 consists of several smaller formations grouped near together1 only their loftiest points being illuminated4 ,the steep borders of the ,mare ,humorum are finely shown4 ,notice how the floor of that little #8sea1' which is about the size of ,england1 as ,mr4 ,elger has remarked1 is mottled with whitish spots1 and how distinct the ring of ,gassendi appears at the northern end of the mare4 ,you can even see the comparatively small crater that crowns the northern wall of the ring4 ,southeast of the ,mare ,humorum are visible the great flat plains of ,schiller and ,schickard4 ,notice also how all the surface of the moon in that direction is freckled with crater pits1 which resemble the impressions made by raindrops in soft sand4 ,but the smallest of these pits is larger than the greatest volcanic crater on the earth4 8,the ,oceanus ,procellarum is beautifully illuminated in this picture4 ,in several places1 particularly north of the ,mare ,humorum1 parts of submerged rings are visible4 ,these are great curiosities1 and we shall see more of them elsewhere4 ,some selenographers believe that they are the remains of an earlier world in the moon1 which was buried by a tremendous upheaval and outrush of molten material from the interior4 ,you will remember1 perhaps1 that ,i spoke of a catastrophe of that kind when pointing out the half-buried ring of ,fracastorius at the southern end of the ,mare ,nectaris40 8,did that catastrophe occur after the formation of the huge lunar volcanoes80 8,it is difficult to say just when it occurred1 but the appearances generally favor the view that it was subsequent to the great volcanic age4 ,it is the opinion of ,mr4 ,elger1 whom ,i have once or twice mentioned as an ,english observer who has devoted special attention to the study of the moon's surface1 that the mares1 as we now see them1 do not represent the original beds of the lunar oceans4 ,these beds1 which1 according to this view1 were at first deeper1 have been covered up1 at least over a great part of their areas1 by the outrush of molten lava4 ,if they were ever filled with water it was very likely prior to that occurrence4 ,but you must remember that all this is speculation1 very interesting1 it is true1 but based upon insufficient data to enable us to be sure of our conclusions4 ,i shall show you later that some recent students of lunar phenomena have formed the opinion that there is a strong argument to be drawn from geological analogies in favor of the view that the lunar mares1 practically in the state in which we see them1 have been true sea beds4 8,let us continue our inspection of photograph ,no4 #ai1 which is one of the most interesting of the series4 ,look at the crater ring ,kepler1 in the midst of the ,oceanus ,procellarum4 ,we have not before seen it in the aspect which it now presents4 ,hitherto it has appeared only as a bright point surrounded by a light patch covered with radiating streaks4 ,but now1 with the late afternoon sunlight striking across it1 its walls are illuminated in such a manner that its very perfect ring shows very clearly1 about half of the interior lying in shadow1 which serves to give it a striking relief4 ,if we suppose a time when the ,oceanus ,procellarum was a real ocean1 and when ,kepler was an active volcano rising above its waters1 its situation1 far from all shores1 would have been not unlike that of the great volcano of ,kilauea in the ,hawaiian ,islands4 ,in that case we might assume that the streaks around it represent ancient lava flows1 which spread far about over the bed of the ocean4 ,the same explanation would apply to the streaks and rays around ,copernicus1 and half a dozen other similar ring mountains4 8,you will also observe that the afternoon slant of the solar rays has considerably changed the appearance of ,aristarchus4 ,now for the first time the crateriform shape of that most remarkable mountain has become evident on account of the shadow in the interior4 ,this shadow has almost reached the central peak which is the brightest part of the entire formation4 ,you may be interested in the fact that the brilliance of the central peak of ,aristarchus is so great that it stands in an order by itself1 in what may be called the photometry of the moon's surface4 ,ten orders of relative brightness have been adopted to represent the various reflective powers of different parts and spots of the moon4 ,i copy them from ,mr4 ,elger's list4 ,they are as follows3 8#j ,black 7example1 the shadows of mountains74 8#a ,gray black 7example1 darkest places in the walled plains of ,grimaldi and ,riccioli74 8#b ,dark gray 7example1 the floor of ,endymion74 8#c ,medium gray 7example1 interior of ,theophilus74 8#d ,yellowish gray 7example1 interior of ,manilius74 8#e ,pure light gray 7example1 surface around ,kepler74 8#f ,light whitish gray 7example1 walls of ,macrobius74 8#g ,grayish white 7example1 ,kepler74 8#h ,pure white 7example1 walls of ,copernicus74 8#i ,glittering white 7example1 ,proclus74 8#aj ,dazzling white 7sole example1 the central peak of ,aristarchus740 8,really1 ,i am greatly surprised by what you tell me10 said my friend4 8,i would never have imagined that there were so many different neutral tints on the moon40 8,you would be still more surprised10 ,i replied1 8if ,i could present to you a similar table of the different tints of color that have been discovered there4 ,but ,i am not aware that any scale of lunar colors has been prepared4 ,there are1 however1 various shades of brown1 yellow1 and green4 ,most of them are found in the mares and walled inclosures4 ,some of them appear to be variable1 and some are only to be detected under particular illuminations40 8,are not such colors an indication of something living there80 8,it may be so--an indication1 for instance1 of the existence of #8lunar grass1' the mention of which so amused you a little while ago40 8,oh1 it was not the #8grass' that amused me1 but your unexpected way of introducing it4 ,i want to be convinced that there is grass there1 and a great many other things besides grass4 ,but ,i am not yet satisfied concerning that unique peak in ,aristarchus4 #8,dazzling white' you say is its description in the scale of tints4 ,that excites my curiosity immensely4 ,i think you have told me already that it cannot be snow1 but you have spoken of the possibility of crystals and of metal4 ,do you know1 ,i like the idea of ascribing the phenomenon to metal4 ,it recalls something that ,i read in childhood about the first discoverer of a silver mine in ,mexico4 ,as ,i remember the story1 an ,aztec hunter1 chasing his game across a mountain1 seized upon a bush to aid him1 and the roots giving way disclosed a glittering mass of silver4 ,why not let me imagine that the peak of ,aristarchus is composed of pure silver80 8,there is no harm in imagining that if you wish to do so4 ,but then your imagination1 or rather your knowledge1 should go a little farther and recall the fact that silver does not remain dazzling bright when exposed40 8,ah1 but you say there is no air1 no water1 no rains1 no moisture on the moon4 ,under such circumstances might not a metal remain bright80 8,it is possible1 but ,i hardly think that it would4 ,it is likely that other corroding influences exist4 ,a better explanation1 ,i think1 is afforded by supposing that the reflecting surface is simply composed of a rocky mineral1 resembling in its power of reflection a mass of quartz crystals or imbedded planes of mica4 ,there is no absolute impossibility involved in thinking that it may be simply white rock40 8,why not say marble--a gigantic ,carrara mountain on the moon80 8,i fear that that would involve a geological history for the lunar world for which we have not sufficient warrant in observed facts4 ,i prefer to assume a volcanic origin for the phenomenon4 ,since you are so interested in the mystery of ,aristarchus ,i may add that a part of the floor and the inner side of the ring are also extremely bright1 but not quite so bright as the central peak4 ,that alone stands at the top of the scale4 ,putting the peak at #aj1 ,mr4 ,elger finds that the other brilliant parts of ,aristarchus possess only #i of brightness4 ,yet the whole interior is so glistening that when the sunlight falls vertically it almost resembles the inside of a crystal cup1 and details are hidden in the glare4 8,now please look at the #8,bay of ,rainbows' in the photograph before us4 ,cape ,laplace at its western end lies close to the terminator and appears as a minute speck of light4 ,the great bow-shaped shore is clearly defined1 the level surface within being very dark and the highlands around it comparatively bright4 ,the crater mountain ,bianchini you will recognize near the center of the bow4 ,several other similar crateriform mountains are visible toward the north and east4 ,in this light the surface of the moon eastward from the ,north ,pole appears as rough and broken with craters and crater plains as we saw in the earlier pictures that it is toward the west4 8,before directing our attention to photograph ,no4 #bj1 let us return for a moment to ,aristarchus4 ,when speaking of that formation a few minutes ago ,i interrupted myself in order to give you the scale of tints on the moon1 which demonstrated the unique brilliance of the peak inclosed by the ring4 ,i intended to point out to you then the fact that in photograph ,no4 #ai we see1 for the first time1 not only the ring of ,aristarchus but its curious neighbor ,herodotus4 ,a light streak1 which we observed in an earlier picture1 seems to connect the two4 ,it is better1 however1 to notice this now because in turning from ,no4 #ai to ,no4 #bj you will perceive once more a change in the appearance of ,aristarchus and its neighborhood4 ,in ,no4 #bj ,aristarchus is distinctly more conspicuous4 ,the night has advanced during almost exactly twenty-four hours1 having in the meantime swept across the entire length of the #8,bay of ,rainbows1' which we now no longer see4 ,if we had been using a telescope during that interval we should have beheld a very interesting spectacle1 for sunset on the #8,bay of ,rainbows' is quite as remarkable1 although in a very different way1 as sunset on the ,bay of ,naples4 ,the astronomer1 seated amid the lonely gloom of his observatory dome1 and watching the change of light and illumination on the surface of the moon1 has many an hour of solitary enjoyment of aspects of nature that are quite impossible on the earth1 and that frequently lure him into poetic meditations which find no place in his notebook40 8,i am very glad to hear you say that4 ,it enhances my opinion of the astronomers1 and convinces me that after all they are not so severely scientific as they describe themselves40 ,illustration3 ,,no4 #bj4 ,,august #ag1 #aijc2 ,,moon',s ,,age #bd4hd ,,days4 8,if they were10 ,i replied1 8or if all of them were1 it would be a bad augury for the future of their science4 ,do not think that in occasionally seeking to restrain your imagination ,i wish to express condemnation of what1 after all1 is the noblest of human faculties4 ,but again we are forgetting our principal business1 which is with the facts4 ,aristarchus1 as ,i have said1 has undergone another distinct change of appearance from that which it showed before4 ,the central peak is now covered by the shadow of the eastern wall1 but still the reflection from the western wall alone is sufficient to make it the brightest spot on the moon4 ,herodotus1 on the other hand1 has become indistinct and the ,harbinger ,mountains are practically invisible1 but we can detect the existence of the enormous chasm or caon1 which ,i told you once issues from the interior of ,herodotus and goes winding nearly a hundred miles over the floor of the ,oceanus ,procellarum4 8,notice1 also1 how clearly visible three or four relatively small craters east of the #8,bay of ,rainbows' have become1 and how conspicuous are several large walled plains on the northern #8horn4' ,the dark level south of these formations and between them and the small craters has also a name which ,i have not before mentioned4 ,it is the ,sinus ,roris1 #8,gulf of ,dew4' ,it connects the ,mare ,frigoris with the ,oceanus ,procellarum4 ,it is another legacy from your friend the imaginative astronomer40 8,then once more he receives my thanks for having done his best to make the moon an ideal world4 ,it is always painful to have one's ideals destroyed40 8,i hope that ,i have not been destroying any of yours40 8,no1 but at least you have caused a change in my impressions about the character of the moon4 ,henceforth there will be an element of terror as well as of unexpected grandeur mingled with my thoughts of the #8,queen of ,night4'0 8,that element will not be diminished by what ,i am about to point out4 ,look far over near the eastern border of the ,oceanus ,procellarum1 directly east of ,aristarchus4 ,there you will distinguish the outlines of two or three vast submerged ring plains1 which we may regard as relics of that earlier lunar world1 which preceded the outgush of lava that ,mr4 ,elger thinks covered the sea bottoms4 ,observe also the singular light streak that runs from ,kepler1 now barely visible at the edge of night1 to a dark little crater1 beyond which lies a bright point off the coast of the #8ocean4' ,south of this there are other submerged ring plains1 one of which1 named ,letronne1 has a high western wall1 which forms in the picture a sort of promontory projecting from the southern border of the ,oceanus ,procellarum1 almost directly north of ,gassendi4 ,the latter is very clearly shown at the lower end of the ,mare ,humorum1 the western side of which is in shadow1 while its whole surface has turned very dark4 ,on the southern horn of the crescent the ring plains1 ,schickard and ,schiller1 are still prominent1 and the northern and eastern edges of the ,mare ,humorum appear more ragged with mountains and crater rings than before40 8,and have all these mountains and craters names80 8,not all of them1 but many more1 perhaps1 than you suppose4 ,on the whole visible surface of the moon about #ejj objects1 not including the #8seas1' have received names4 ,it may surprise you to learn that the position of the most important of these objects has been ascertained with an accuracy which is still lacking in our determination of positions on the earth4 ,in other words our charts of the moon are more exact than those of our own planet40 8,that does indeed surprise me4 ,i should have thought that1 living on the earth1 we could make very correct maps of it1 while1 as for the moon1 two or three hundred thousand miles away1 it seems to me not so easy to do that40 8,it is mainly because we are on the earth that we find such great difficulty in making accurate maps of it4 ,we cannot look at the earth as a whole1 but we have to crawl over its surface1 making measurements as we go1 and afterwards translating those measurements into lines and angles on paper4 ,thus we are still uncertain about the precise distance between many important points on our globe1 while for points on the moon no corresponding uncertainty exists4 ,the moon hangs before us in the sky1 with no clouds except those in our own atmosphere to obscure it1 and it is only necessary carefully to observe the position of particular points1 and with the proper instruments to measure their distance and directions from one another4 ,but even this is not a thing that can be accomplished without much pains and much knowledge4 ,the astronomer1 no matter what field he chooses1 is necessarily a hard worker1 and his motto1 above everything else1 is accuracy4 ,no one is more tempted than he by the sublimity and the extraordinary character of the objects of his study1 to give rein to the imagination1 and yet imagination is the thing of all others from whose vagaries he must most carefully guard himself4 ,so you must not blame him too severely if he has not dotted the shores of the moon with cities1 and populated its plains with industrious farmers40 8,if you will permit me to wander a little aside from our photographic studies for a few minutes10 said my friend1 8,i should like to ask you about two or three things concerning the moon which have long puzzled me4 ,from my earliest days1 living the greater part of the time in the country1 ,i have heard that the moon exercises a decided influence over the weather1 and over the growth of vegetation4 ,i have neighbors who would never think of planting certain things except #8in the ,new of the moon'6 ,some will not cut timber except #8in the ,old of the ,moon1' as they say that the sap is drawn up by the moon's influence when she is growing4 ,is there really any truth in all this80 8,not the least4 ,at any rate there is no scientific evidence whatever for such statements1 and no probability that they are based on facts4 ,they are the result of faulty observation1 misled by coincidences4 ,it is imaginable that the light of the moon might have some influence upon vegetable growth if it were an original kind of light coming from the moon herself4 ,but moonlight is only reflected sunlight1 and when we examine it with the spectroscope we do not find that the rays of light in visiting the moon and returning thence to the earth have had either anything added to or anything taken away from them1 except intensity4 ,the total amount of light reflected from the moon upon the earth is estimated to be about #a_/fahjjj of the total amount that comes to us from the sun4 ,curiously enough the moon appears to reflect proportionally more heat than light1 the amount of lunar heat received by the earth being reckoned at #a_/ahejjj of the amount coming from the sun4 ,the popular idea that the moon affects the movement of sap in plants is equally illusory40 8,but about the weather8 ,i know people who believe that a change of the moon from one phase to another brings about a change of weather4 ,is that true80 8,certainly it is not true4 ,the moon is changing its apparent form all the time4 ,there is no sudden alteration at any phase4 ,the popular belief1 however1 has always been so firmly fixed that many investigations have been made to ascertain whether there is1 in reality1 any foundation for it4 ,these investigations have shown that no measurable effect of the kind exists40 8,and the ,full ,moon does not drive away clouds1 as some assert80 8,surely she does not4 ,i will now tell you something that the persons who plant and sow and cut timber according to the phases of the moon1 and who believe that she exercises a kind of magic control over the clouds1 probably have never heard of1 although if they knew it they might use it as an argument in favor of lunar influences4 ,it is this3 ,the alternate approach and retreat of the moon with respect to the earth1 as she travels round her elliptical orbit1 produce measurable1 although slight1 disturbances of the magnetism of our planet4 ,the distance of the moon varies to the extent of about #cj1jjj miles4 ,now1 if it could be shown that these magnetic disturbances were reflected in the character of the weather1 then the supposed influence of the moon would be established4 ,but that has not been shown1 and if it were shown it would still be found that the phases of the moon had no relation to the fact1 for the moon may be at its greatest or its least distance from the earth1 or at any intermediate distance during any possible phase40 8,you will1 perhaps1 think me very persistent in asking foolish questions1 but there is one other on my mind that ,i should like to put1 now that we have gone so far4 ,it is this3 ,i have read1 since the great earthquakes at ,san ,francisco and ,valparaiso1 and the great eruption of ,vesuvius in the same year1 #aijf1 that the moon has an influence over such things4 ,is this another unfounded popular superstition80 8,it is not a notion of popular origin at all10 ,i replied4 8,it originated rather from scientific considerations1 and there may possibly be a germ of truth in it1 although it yet remains to be demonstrated1 and the evidence concerning it is confusingly contradictory4 ,you will recall1 ,i trust1 what has been said about the sun and the moon producing tides in the oceans4 ,we have also seen that before our globe had assumed its present condition1 while it was yet more or less plastic throughout its whole mass1 and before the birth of the moon1 great tides were produced in the body of the earth4 ,the tendency to the production of such bodily tides still exists1 and now that the moon has become a near-by attendant of the earth1 she acts more effectively in this regard than does the sun4 ,if the earth were still plastic the moon would produce bodily tides in it4 ,in other words the earth would be deformed by the attraction of the moon4 ,the question has arisen whether or not the tendency to the production of such tides1 now that the earth has become rigid1 may not disturb its crust sufficiently to induce earthquakes and volcanic eruptions4 ,some students of the subject have thought that they could detect evidence that this is the case4 ,it has frequently happened that such phenomena have occurred on a large scale1 at or very close to1 the periods of ,new and of ,full ,moon4 ,those are the times1 as we saw when we were talking of the oceanic tides1 when the sun and the moon pull together4 ,if all great eruptions and earthquakes occurred at these conjunctions there would be little doubt of the correctness of the theory4 ,but1 unfortunately for the clearness of our conceptions1 this is by no means the case4 ,there have been many earthquakes and volcanic outbursts when the sun and the moon were not thus combining their tidal attractions4 ,thus the evidence is found to be contradictory or inconsistent1 and the question remains unsettled4 ,it is1 however1 a very interesting one1 and the time will come1 it is to be hoped1 when it will be answered decisively one way or the other40 ,after this digression we returned to the study of the photographs4 8,photograph ,no4 #bj1 which we have just been examining10 ,i said1 8represents the moon at the age of about twenty-four days and twenty hours4 ,the next1 and the last of the series showing the moon in progressive phases1 is ,no4 #ba4 ,here the age of the moon is about twenty-six days and twenty hours4 ,it is the fast waning sickle of the ,old ,moon which we behold4 ,you perceive that it is relatively uninteresting when compared with ,no4 #bj1 because very little except the eastern limb is illuminated4 ,nearly all the great circular and oval formations and craters1 and all the #8seas1' have passed into the lunar night4 ,only the eastern verge of the ,oceanus ,procellarum remains in sight1 dulling the brilliance of the inner curve of the sickle4 ,the dark walled plain above the center is ,riccioli1 and just below it appears ,hevel1 a smaller1 but yet large formation1 with a low central mountain4 ,it is hardly worth our while to attempt to identify the other features shown in the photograph4 ,they include none that we have previously studied4 ,yet this picture has an interest all its own because it is an excellent representation of the moon at a time when she is so near to the sun4 ,do not forget that1 as ,i warned you when we began with the crescent of the ,new ,moon1 in these photographs the moon appears reversed top for bottom4 ,seen in the sky in the early morning this sickle would have its rounded edge toward the left hand and directed more or less downward1 according to the position of the sun4 ,a great deal of confusion exists in the minds of well-educated people concerning the position of the sickle of the ,new and the ,old ,moon4 ,you have1 of course1 heard of the classic instances in which artists have drawn the ,new ,moon with the concave side toward the sun6 ,it is only necessary to remember that a line drawn straight from the center of the convex side of the sickle1 whether it be the ,new ,moon or the ,old ,moon1 always extends directly toward the place occupied by the sun40 ,illustration3 ,,no4 #ba4 ,,august #ai1 #aijc2 ,,moon',s ,,age #bf4hi ,,days4 8,there is10 said my friend1 8an interesting old superstition which ,i have often heard--,i suppose it must of course be a superstition--concerning #8wet moons' and #8dry moons4' ,as ,i recall it they say that when the sickle of the ,new ,moon appears nearly upright in the sky that is a sign of dry weather1 because the moon is then like an overturned cup1 but when the sickle has its ends turned upward that is a sign of wet weather1 because then the cup can hold water4 ,i suppose that these various positions of the moon actually occur1 but ,i do not know how they are brought about40 8,the supposed influence of the position of the ,new ,moon on the weather10 ,i replied1 8is too gross a superstition to be worthy of any notice1 but the different attitudes of the sickle are interesting4 ,they arise from the changes in the position of the moon as seen from the earth with respect to the direction of the sun1 and these changes depend in turn on the inclination of the moon's path in the sky to the plane of the earth's equator as well as to the plane of the ecliptic or the earth's orbit4 ,the ecliptic has an inclination of about #bc to the plane of the equator1 and the moon's orbit is inclined a little over #e to the ecliptic4 ,the moon may1 in consequence1 appear more than #bh above or below the equator4 ,but since1 as ,i told you in the beginning1 the orbit of the moon itself turns slowly about in space1 the distance of the moon above or below the equator is not constant4 ,it may be only a little more than #ah4 ,in consequence of these changes of relative position the situation of the horns of the crescent moon varies4 ,but you need never be in doubt as to what position they will occupy at any time if you will simply remember that a straight line drawn from the point of one horn to that of the other must always form a right angle with the direction of the sun4 ,illustration3 ,diagram ,showing ,why the ,winter ,moon ,runs ,high4 8,there is another very interesting fact about the position of the moon in the sky which we should not neglect to notice4 ,did you ever observe the superior brilliancy of the light of the ,full ,moon in winter8 ,it is one of the compensations that nature offers us4 ,since the ,full ,moon is necessarily situated opposite to the point occupied by the sun1 and since the sun is far south of the equator in midwinter1 it follows that at the same season the ,full ,moon appears high above the equator in the northern hemisphere4 ,you will1 perhaps1 permit me to show you a diagram intended to explain this phenomenon4 ,you observe that the sun being south of the equator1 in the direction indicated by the dotted line1 the ,full ,moon is correspondingly situated north of the equator1 and must necessarily appear high in the sky at midnight1 when the sun is at its lowest declination4 ,this is the reason why the winter ,full ,moons are so brilliant1 making the snow-clad hills gleam with a splendor that sometimes dazzles the eyes of the beholders4 ,in the ,arctic regions the long winter night1 when the sun does not rise for months1 is periodically brightened by the presence of the ,full ,moon4 ,just the opposite condition of affairs exists in summer4 ,then the sun being north of the equator the ,full ,moon is south of it1 and #8runs low1' appearing in high latitudes to skim along the southern horizon40 8,thank you1 and now ,i will ask you one more question10 said my friend4 8,i have often heard of the #8,harvest ,moon' and the #8,hunter's ,moon4' ,will you not kindly explain what is meant by these terms and when the #8,harvest ,moon' can be seen8 ,there is a poetic suggestiveness in the name that appeals to me40 8,i will try with pleasure10 ,i said1 8but ,i fear that ,i shall have to trouble you with another diagram1 or perhaps with two40 8,oh1 ,i shall not mind that at all4 ,i have grown used to diagrams as well as to the nomenclature of the moon40 8,well1 if my diagrams conduct your thoughts to things as interesting as many that lie concealed behind the prosaic names on the moon ,i shall be content4 ,to begin1 then1 ,i must remind you that in her monthly journey around the earth the moon moves from west toward east in her orbit1 and thus she gets a little over #ab farther east every twenty-four hours1 as reckoned from the position of the sun4 ,the earth turning on its axis in the same direction causes the moon to appear to rise in the east and set in the west once every twenty-four hours4 ,but in consequence of the constant eastward motion of the moon she rises at a later hour every night4 ,here is a graphic representation of what ,i mean3 8,the earth is turning on its axis in the direction represented by the arrows1 and simultaneously the moon is moving in its orbit in the same direction1 as is shown by the large arrow4 ,suppose that some night the moon is seen rising at a particular hour from the point ,a on the earth4 ,then1 the following night1 when the observer has again arrived at ,a1 with the rotation of the earth1 the moon will have advanced from ,m#a to ,m#b1 and will not be seen rising until the point occupied by the observer has arrived at ,b4 ,this retardation of the hour of moonrise is variable on account of changes in the position of the moon1 arising from the inclination of her orbit to the plane of the equator1 and from the inequalities of her motion1 to which ,i have before referred4 ,on the average it amounts to fifty-one minutes daily4 ,it varies also with the distance of the observer from the equator1 the variation being greater in high latitudes4 ,in the latitude of ,new ,york the retardation of moonrise may be as great as an hour and a quarter1 or as little as twenty-three minutes4 ,illustration3 ,diagram ,showing ,why ,moon ,rises ,later ,every ,night4 8,now it is upon this variation that the phenomenon of the #8,harvest' and the #8,hunter's ,moon' depends4 ,if ,i had a celestial globe here ,i could show you that at the time of the ,autumn ,equinox1 ,september #bb;d1 when the sun crosses the equator moving southward1 the apparent path of the moon in the sky intersects the eastern horizon at a comparatively small inclination4 ,in other words the moon at that time instead of rising steeply from the horizon rises on a long slope almost parallel with the horizon4 ,the consequence is that for several evenings in succession the ,full ,moon near the time of the ,autumn ,equinox may be seen rising just after sunset at almost the same hour4 ,look at this second diagram and you will see why this is so4 ,illustration3 ,diagram ,illustrating the ,harvest ,moon4 8,the little circles ,m show the moon at several successive positions in her orbit1 just twenty-four hours apart4 ,you perceive that in consequence of the slight inclination to the eastern horizon the sinking of the latter caused by the earth's rotation will bring the moon into view night after night at almost the same hour4 ,in fact1 in high northern latitudes like those of ,norway and ,sweden the moon's path at this time of the year may actually coincide with the horizon1 so that for several evenings she will rise at exactly the same hour4 ,the name #8,harvest ,moon' explains itself1 since it always occurs at the time of the autumn harvests and the vintage1 and seems to supplement the fading daylight for the benefit of late laborers in the fields4 ,the #8,harvest ,moon' does not occur every year at precisely the same date4 ,it is very rare that ,full ,moon happens to fall just on ,september #bb;d4 ,it usually either precedes or follows that date4 ,the #8,harvest ,moon' is the ,full ,moon which occurs nearest to the ,autumn ,equinox1 either before or after4 ,the #8,hunter's ,moon' is the first ,full ,moon which follows the #8,harvest ,moon4' ,like the former it rises for several successive evenings near the same hour1 but this phenomenon is less marked in the case of the #8,hunter's ,moon1' because it is farther from the ,equinox40 8,thank you1 again10 said my friend4 8,i shall never henceforth look at the moon without thinking of circles1 straight lines1 and arrows as well as of #8ring mountains' and #8seas4'0 8,then you are making good progress toward science10 ,i replied4 8,one last look1 now1 at the photograph of the ,old ,moon's sickle1 and then we had better postpone our examination of the large photographs1 showing certain particularly interesting districts on the moon1 until to-morrow morning4 ,there is here another interesting point for artists to note4 ,the convex side of the sickle of the ,old ,moon1 or the ,new ,moon1 is always an arc of a circle1 but the concave side is never circular although it is often thus represented4 ,the concave side1 neglecting its irregularities arising from the differences of level and of brilliancy of the lunar surface1 is elliptical in outline1 that is to say1 it is a semicircle viewed obliquely40 8,whatever its geometry may be10 replied my friend1 8it is certainly very beautiful4 ,good night1 and ,i shall demand to see those large photographs before the sun is very high to-morrow40 ---------------------------------------- -------------------------------- ,,iv ,,great ,,scenes ,,on ,,the ,,moon ---------------------------------------- -------------------------------- ,,iv ,,great ,,scenes ,,on ,,the ,,moon ,,my friend did not leave me in doubt on the following morning as to the genuineness of her interest in her new studies4 ,the shadows of the trees in the park were yet as long drawn out as the silhouettes of lunar peaks at sunrise1 when we resumed our place under the elm1 and1 at her request1 ,i opened once more my portfolio4 8,the series of photographs that we are now about to examine10 ,i began1 8are on so large a scale that only a selected part of the moon is seen in each of them4 ,but within the restricted limits of these pictures the amount of detail shown is truly astonishing1 far more indeed than can be found on the most elaborate lunar charts4 ,these photographs were made by ,mr4 ,ritchey with the great #dj-;inch telescope of the ,yerkes ,observatory4 ,many more besides those that we are going to look at were taken by him1 but ,i have selected1 where choice was difficult1 six which seemed to me to be of special interest4 ,we shall begin with one which covers the larger part of the ,mare ,nubium1 in the southeastern quarter of the moon4 ,you certainly must remember the ,mare ,nubium1 for it forms the head of the #8dark woman' whom you discovered in the moon last evening1 and if you will hold this photograph at arm's length you will see that her face is unmistakably stamped upon it40 8,i am greatly flattered10 she replied1 8that you should remember my discovery so well4 ,i begin to feel hopeful that it may yet find a place in the books40 8,it certainly is as deserving of such a place as many things that get into books4 ,you ought to find a suitable name for this woman in the moon40 8,if ,i believed myself capable of rivaling the man who christened the #8,marsh of a ,dream1' ,i should surely try my hand at lunar nomenclature1 but ,i fear that ,i should fall too far short of the ideal he has set up1 and so ,i shall leave her nameless40 8,permit me then to continue to call her the #8dark woman' whenever a reference to her may seem useful in fixing the localities that we shall talk about in this photograph4 ,the most striking object shown in the picture is the great ring mountain ,bullialdus which forms an extraordinary ornament on the top of the #8dark woman's' ear4 ,this photograph was taken when the line of sunrise ran just along the border between the ,mare ,nubium and the ,oceanus ,procellarum4 ,the ,mare ,humorum is yet buried in night beyond the upper right-hand edge of the picture1 but some of its bordering mountains and craters have been touched by the morning sunbeams4 ,you will observe that a little more than half of the interior of ,bullialdus--which1 by the way1 ,i did not mention by name when we were studying the series of phase photographs--is yet filled with shadow1 but its double-headed central peak rises clear and bright in the sunlight4 ,the shadow of this central mountain can be seen projecting toward the east over the floor4 ,the east wall1 which is distinctly terraced1 lies in full sunshine1 and the light streaming over the lofty crest of the western wall touches the floor on its eastern half4 ,the steep outer slopes that lead up to the western rampart1 and the deep parallel ravines cut near the crest are clearly shown4 ,the distance across the ring from the summit of the wall on one side to that on the other is #ch miles4 ,the depth of the depression is #h1jjj feet below the crest of the walls1 but the latter rise only #d1jjj feet above the level of the ,mare ,nubium outside1 so that ,bullialdus is an excellent example of the characteristic form of the lunar volcano1 which ,i tried to illustrate for you last evening4 ,the central mountain is #c1jjj feet high4 ,east of the south point of the ring a shadow shows the existence of a profound cleft in the wall1 while a little west of south appears a smaller crater ring very black with shadow1 except on its eastern side4 ,if we stood on the ,mare ,nubium and looked toward ,bullialdus and its neighbor from a distance of #be or #cj miles they would resemble a double1 flat-topped mountain1 with its serrated crests connected by a high neck4 ,the summit of one of the little peaks shown in the photograph in the plain just west of ,bullialdus would form an excellent point of observation4 ,still farther south stands another crater ring most of whose interior is also1 at present1 filled with shadow4 ,east of this1 and a little farther south1 is still a third ring of similar aspect1 from which a curious range of hills runs southward4 ,returning to ,bullialdus you will notice the radiating lines of hills that surround it1 and particularly a more lofty and broken range which runs eastward40 ,illustration3 ,,bullialdus ,,and ,,the ,mare ,nubium4 8,bullialdus verily frightens me60 exclaimed my friend4 8,what an unearthly look it has6 ,the longer ,i regard it the stronger becomes the indescribable impression that it produces4 ,i begin to understand now what you meant when you promised to find a history in the moon4 ,truly there never can have been such another history4 ,i almost feel that ,i do not care whether the moon ever had inhabitants or not4 ,its own story is more fascinating than that of any puny race of beings1 passing their ephemeral lives upon its wonderful surface1 could possibly be40 8,i am glad10 ,i replied1 8that you have begun to enter into the spirit of those who long and carefully study the earth's satellite4 ,you see now1 that it is not necessary to the astronomer to find evidences either of former or of present life upon the moon in order to stimulate his zeal4 ,for him1 as you have yourself intimated1 the relics of its past history1 which this little world in the sky exhibits so abundantly1 are of higher interest than any story of human empire1 for they have an incomparably vaster theme4 ,but to lighten our labor a little1 let me once more refer to the #8dark woman1' whose features1 like the outlines of a constellation1 serve for points of reference4 ,i began by remarking that ,bullialdus seems to be placed just over her ear4 ,observe now that1 taken together with its immediate surroundings1 the great crater ring forms a kind of barbaric ear-ornament of most extraordinary form and richness of detail4 ,the line of hills east of ,bullialdus1 of which ,i spoke a few minutes ago1 connects the ring with a tumbled mass of mountains on the border of the ,mare ,humorum4 ,these mountains run northward1 or downward in the picture1 for a distance of perhaps #aej miles1 and then turn abruptly westward for a like distance2 after which1 in the form of a broken chain1 constituting the eastern walls of a row of half-submerged ring plains1 they change direction once more and run southward in the ,mare ,nubium4 ,the whole system bears some resemblance to a gigantic buckle40 8,what is that curious object below ,bullialdus which resembles an old-fashioned gold earring80 8,i was about to speak of that4 ,it is a ring plain named ,lubiniesky1 about #bc miles in diameter with a wall a thousand feet in height1 except in the direction of ,bullialdus where it is broken down4 ,the interior is very flat1 and it forms a fine example of the half-submerged lunar volcanoes which abound in this hemisphere4 ,it may have had a central mountain like ,bullialdus1 but if so it has been completely buried under the influx of molten lava or whatever it was that covered this part of the moon4 ,the perfect form of ,bullialdus in all its details when compared with the mere outline that remains of ,lubiniesky indicates that the former probably burst forth after the inundation of liquid rock that drowned the latter4 ,thus we have in these two neighboring formations two chapters of lunar history which1 like the monuments of ,egypt1 tell the story of widely separated epochs4 ,the row of still more completely submerged crater rings westward from ,lubiniesky and ,bullialdus show by their condition that the depth of the lava flood was probably greater in their vicinity than it was farther eastward4 8,now look southward from ,bullialdus1 at a distance about twice as great as that of ,lubiniesky and you will see another partially submerged ring1 with a more serrated crest4 ,the name of this is ,kies4 ,it is remarkable for the lofty mountain spur which sets off from its southern wall1 and also for the fact that one of the bright streaks from ,tycho--one of a parallel pair that ,i pointed out to you last evening--traverses its flat floor and continues on1 broadening as it goes1 to a deep crater ring which we have already noticed1 southeast of ,bullialdus4 8,south of ,kies1 at the edge of the ,mare ,nubium1 is a lofty mountain range whose summits and slopes are very bright in the sunrise4 ,at one point a great pass breaks through these mountains1 leading to a sort of bay shut in on all sides by precipices and the walls of gigantic crater rings4 ,the large crater ring at the eastern corner of this bay is ,capuanus4 ,the smaller ring on its western side with a conspicuous crater on its eastern wall is ,cichus4 ,notice the fine shadow that ,cichus casts1 whose pointed edge is evidently due to the little crater on the wall4 ,that #8little' crater is six miles across6 ,the twin rings apparently terminating the mountain mass northeast of the bay are ,mercator and ,capuanus4 ,between these and ,kies you perceive two short ranges of small mountains and then a kind of round swelling of the surface of the plain resembling a great mound4 ,these formations are rare on the moon4 ,they look like bubbles raised by imprisoned gases4 ,the ,united ,states ,geological ,survey has discovered something similar in form1 but infinitely inferior in magnitude1 in the great mud bubbles that rise to the surface of the ,gulf of ,mexico off the mouth of the ,mississippi ,river4 ,but ,i do not mean to aver that the two phenomena are similar in origin4 8,near the southern shore of the ,mare ,nubium appears a long1 dark line which starts at the edge of a crater ring1 crosses the southern arm of the #8sea1' evidently penetrates the bordering mountains1 and reappears traversing the dark bay near its northern edge1 cleaving both walls of a small crater ring in its way4 8,i should weary you1 perhaps1 with too much detail if ,i undertook to identify all of the prominent objects in this photograph4 ,returning to the southern shore of the ,mare ,nubium1 ,i shall simply call your attention to the very large ring plain with terraced walls and a peak a little east of its center4 ,this is ,pitatus4 ,an enormous ravine breaks through its eastern side and connects it with a smaller ring from which the dark line already mentioned starts4 ,this dark line represents one of the most remarkable clefts on the moon4 ,it looks as though the crust had been split asunder there over a distance of at least #aej miles4 ,it bears some resemblance to the great caon near ,aristarchus and ,herodotus1 except that the latter is very tortuous and this is nearly straight40 8,have ,i not heard of something similar in connection with the ,california earthquake in #aijf80 asked my friend4 8,no doubt you are thinking of the great #8fault' which geologists have discovered off the ,pacific coast of ,north ,america4 ,there is perhaps some resemblance between these phenomena4 ,pitatus1 ,i may add1 is #eh miles in diameter4 ,you will observe how its southern wall has apparently been broken down by the deluge of lava which buried so many smaller rings in the ,mare ,nubium4 ,if you will now turn your attention to the left-hand side of the photograph1 somewhat above the center1 you will perceive a very strange object1 the so-called #8,straight ,wall4' ,it lies just west of a large conical crater pit which has a much smaller pit near its western edge4 ,you might easily mistake the #8,straight ,wall' for an accidental mark in the photograph4 ,it is not absolutely straight1 and near its southern end it makes a slight turn eastward and terminates in a curious1 branched mountain1 whose most conspicuous part is crescent-shaped4 ,the wall is about #fe miles in length and #ejj feet in height4 ,it is as perpendicular on its east face as the ,palisades on the ,hudson4 ,it is not a ridge of hills at all1 but a place where the level of the ground suddenly falls away4 ,approaching it from the west you would probably be unaware of its existence until you stood upon its verge4 ,the dark line that we see in the photograph is the shadow cast by the wall upon the lower plain4 ,in the lunar afternoon the appearance is changed1 and the face of the cliff is seen bright with sunlight4 ,this curious object has attracted the attention of students of the moon for generations1 and many speculations were formerly indulged in concerning its possible artificial origin4 ,it has sometimes been called the #8,lunar ,railroad4' ,manifestly1 whatever else it may be1 it is not artificial4 ,the closest analogy perhaps is with what we were speaking of a little while ago1 a geological fault1 that is to say1 a line in the crust of the planet where the rocky strata have been broken across and one side has dropped to a lower level4 8,the crater pit in the ,mare ,nubium1 east of the #8,straight ,wall1' is named ,birt1 and its twin1 #ge miles farther east1 is ,nicollet4 ,look now at the hooked nose of your #8dark woman4' ,the huge wart upon it is a crater plain named ,lassell4 ,between the lower end of the #8,straight ,wall' and ,lassell1 and over the bridge of the #8nose1' a wedge-shaped mountain runs out into the mare4 ,this is called the ,promontorium narium1 and must have formed a magnificent outlook if ever a real ocean flowed at the foot of its cliffs4 ,the ring with a crater on its wall below ,lassell is ,davy4 ,you will note some very somber regions scattered over this part of the ,mare ,nubium4 ,one of them forms the #8dark woman's' eye1 and just over it1 like an eyebrow1 is a curving range of hillocks1 including some little craters4 ,on the #8cheek'--,i am still utilizing the #8dark woman' as a kind of signboard--at the base of the #8chin1' appears a partly double range of large ring plains4 ,the greatest of these1 at the bottom1 is named ,fra ,mauro1 and you will notice within it a curious speckling of small craters4 ,adjoining ,fra ,mauro on the south are two intersecting rings1 ,barry being the name of the western and ,bonpland that of the eastern one4 ,the partially submerged ring is nameless1 as far as ,i know1 while the upper or southern member of the group1 with a broad valley shut in between broken mountain walls opening out of its northern side1 is ,guerike4 ,there is only one other object1 on the extreme lower right-hand corner of the picture1 to which ,i will ask your attention4 ,it is a singular range of mountains thrown into a great loop at its northern end1 and known as the ,riphan ,mountains40 8,it seems to me10 said my friend1 putting her elbow on the table1 and leaning her head a little wearily on her hand1 8that there is a great sameness in these lunar scenes--always crater rings with or without central mountains1 always peaks and ridges and chasms and black shadows4 ,truly variety is lacking40 8,but what could you expect80 ,i replied4 8,is it not enough to stimulate your curiosity that you are looking intimately into the details of a foreign world8 ,when you go to ,europe you see there mountains1 plains1 rivers1 lakes1 cities1 people1 absolutely identical in their main features with what you see in ,america4 ,but you find them endlessly interesting because of their comparatively slight differences from similar things with which you are familiar1 because of the great age of many of the objects to which your attention is directed1 because of the long course of history which they represent1 and principally1 perhaps1 because you are aware of the sensation of being far from home4 ,it ought to be the same for you here on the moon4 ,these things that we are looking upon belong to a globe suspended in space #bci1jjj miles from the earth4 ,if the features of our globe are practically the same everywhere1 differing only in the arrangement of their details1 you should not be surprised at finding that nature does not vary from her rule of uniformity on the moon4 8,in the next photograph of the series10 ,i continued1 8we have a marvelous specimen of the lunar landscapes4 ,it is perhaps the most rugged region on the moon4 ,it includes two objects of supreme interest1 ,tycho1 the #8,metropolitan ,crater1' and ,clavius1 the most remarkable of the ring plains4 ,you will no doubt recognize ,tycho at a glance4 ,it is near the center of the picture4 ,like the last photograph this one represents an early morning scene4 ,the western wall of ,tycho throws a broad1 irregular crescent of shadow into the cavernous interior1 but all of the eastern1 northern1 and southern sides of the wall are illuminated on their inner faces4 ,the central mountain group is emphasized by its black shadow4 ,a little close inspection reveals the existence of the complicated system of terraces by which the walls drop from greater to lesser heights until the deep sunken floor is reached4 ,the diameter of ,tycho is #ed miles1 and it is at least #ag1jjj feet deep1 measured from the summits of the peaks that tower on both the eastern and the western sides of its wall4 ,the vast system of bright streaks radiating from ,tycho is not seen here1 the time when the photograph was made being too near the sunrise on this part of the moon4 ,the dish-shaped plains crowded around ,tycho form a remarkable feature of this part of the lunar surface4 ,it would be useless to mention them all by name1 and ,i shall ask your attention only to some of the principal ones40 8,thank you for being so considerate10 said my friend1 smiling4 8,i am sure that ,i should forget the names as fast as you mentioned them40 ,illustration3 ,,tycho1 ,,clavius1 ,,and ,,their ,,surroundings4 8,oh1 ,i have no fault to find with your memory10 ,i replied4 8,i doubt if many selenographers could recall them without referring to a chart4 ,let us begin with the greatest of all1 ,clavius1 which1 you see1 is near the top of the picture4 ,i think ,i told you before that ,clavius is more than #adj miles across4 ,the great plain within the walls sinks #ab1jjj feet below the crest of the irregular ring1 but the plateau outside1 on the west1 is almost level with the top of the ring4 ,it is difficult to imagine a more wonderful or imposing spectacle than that which ,clavius would present to a person approaching it from the western side1 and arriving at about the time when this photograph was made1 on the top of the wall4 ,notice how in one place the summit of a ridge1 standing off on the inner side of the western wall1 has come into the sunlight1 and think of the frightful chasm that must yawn between4 ,clavius is so enormous that the two crater rings1 each with a central mountain standing on its wall1 seem very small in comparison with the giant that carries them1 and yet they are #be miles in diameter6 ,stretched out into a straight line1 the tremendous wall of ,clavius would form a range of towering mountains1 extending as far as from ,buffalo to ,new ,york4 ,look at the curved row of craters1 the smallest larger than any on the earth1 which runs across the interior4 ,in addition to these there are many smaller craters and mountains standing on the vast sunken plain1 some of them looking like mere pinholes1 and yet all of really great size40 8,truly10 interrupted my listener1 8the giantism--,i think that is the word you employ--the giantism of the moon appalls me6 ,how can ,i ever think1 again1 that the so-called great spectacles of nature on the earth are really great8 ,you have destroyed my sense of proportion4 ,such immense things standing on a world so small as the moon--why it seems contrary to nature's laws40 8,i have already told you that the very smallness of the moon may be the underlying cause of the greatness of her surface features4 ,and ,i may now add that if your imagined inhabitants ever existed they1 too1 may have been affected with #8giantism4' ,a man could be #cf feet tall on the moon and well proportioned at that1 without losing anything in the way of activity40 8,indeed6 ,you almost make me hope that there never were such inhabitants1 for what beauty could there be in a human being as tall as a tree80 8,very little to our eyes1 perhaps4 ,you recall the impressions of ,gulliver in the land of the ,brobdingnags4 ,however1 they are not my inhabitants but yours1 and if the law of gravitation says that they must have been twelve yards tall1 then twelve yards tall they were4 ,take comfort1 nevertheless1 in the reflection that1 after all1 we cannot positively assert that gravitation alone governs the size of living beings on any particular world4 ,we have microscopic creatures as well as whales and elephants on the earth1 and human stature itself is very variable40 8,thank you1 again4 ,you have saved my lunarians4 ,and now please tell me what is that frightful black chasm above ,clavius80 8,it is a ring plain named ,blancanus1 #ej miles in diameter1 and exceedingly deep4 ,it is so black and terrible because complete night yet reigns within it1 except on the face of its eastern wall4 ,it is really a magnificent formation when well lighted1 but like so many other great things it suffers through its nearness to the overmastering ,clavius4 ,when ,goliath was in the field his fellow ,philistines cut but a sorry figure4 ,look at the marvelous region just below ,blancanus and imagine yourself entangled in that labyrinth6 ,you would have but a small chance for escape1 ,i fancy40 8,i am sure ,i should never have the heart to even try to get out of it4 ,one might as well give up at once40 8,yes1 you are probably right4 ,but ,i will direct you to something not quite so frightful1 although still very formidable in appearance4 ,still farther below you observe a huge ring plain whose eastern wall is brightly illuminated1 while nearly all the interior plain1 although comparatively dark in tone1 lies in the sunshine4 ,it is ,longomontanus4 ,i pointed it out to you in one of the smaller photographs4 ,longomontanus is #ij miles across and #ac1jjj or #ad1jjj feet deep1 measured from its loftiest bordering peaks4 ,the very irregular formation below it is ,wilhelm ,i4 ,it is remarkable for the mountainous character of its interior40 8,for what ,william was it named80 8,i do not know4 ,we are now near the southern border of the region that we inspected in the preceding photograph4 ,in the lower part of this picture you perceive some of the projecting bays of the ,mare ,nubium1 and you can see again the remarkable cleft of which ,i spoke4 ,the large ring near the bottom of the picture is ,pitatus with its smaller neighbor ,hesiodus4 ,it is from the eastern side of the latter that the cleft apparently starts4 ,pitatus1 you see1 has a central peak1 while ,hesiodus1 as if for the sake of contrast1 possesses only a central crater pit4 ,the ravine connecting the two is plainly visible4 ,toward the east you will recognize again ,cichus1 with its crater on the wall and its broad shadow with a sharp point1 while still farther east1 on the very edge of night1 yawns ,capuanus4 ,the two walled plains above ,pitatus are ,gauricus on the left and ,wurzelbauer on the right4 ,the hexagonal shape of the former is very striking4 ,this is a not uncommon phenomenon where the lunar volcanoes and rings are closely crowded1 and it suggests the effect of mutual compression1 like the cells of a honeycomb4 ,away over in the northwestern corner is a vast plain marked by a conspicuous crater ring which bears the startling name of ,hell4 ,it borrows its cognomen1 however1 from an astronomer1 and not1 as you might suppose1 from ,dante's #8,inferno4' 8,before quitting this photograph permit me to recall you to the neighborhood of ,tycho and ,clavius4 ,to the left of a line joining them you will perceive a flat1 oval plain with a much broken mountain ring4 ,this is ,maginus4 ,last evening while we were looking at one of the smaller photographs ,i pointed it out under a more favorable illumination1 telling you at the same time that it possessed the peculiarity of almost completely disappearing at ,full ,moon4 ,already1 although day has not advanced very far upon it1 you observe that it has become relatively inconspicuous4 ,this is a lesson in the curious effects of light and shadow in alternately revealing and concealing vast objects on the moon4 ,you will notice that in many particulars ,maginus resembles a reduced copy of ,clavius4 ,but the walls of ,clavius are in a comparatively perfect condition while those of ,maginus have apparently crumbled and fallen1 destroyed by forces of whose nature we can only form guesses4 ,evidently the destruction has not been wrought1 like that of some of the rings in the ,mare ,nubium1 by an inundation of liquid rock from beneath the crust4 ,it resembles the effects of the #8weathering' which gradually brings down the mountains of the earth1 but if such agencies ever acted upon the moon1 then it must have had an atmosphere and an abundance of water4 ,in any event1 here before us is another page of lunar chronology4 ,maginus is evidently far older than ,clavius2 ,clavius is older than the craters standing on its own walls40 ,we now took up the third of the large photographs representing a part of the southwestern quarter of the moon1 more extraordinary for its mountains1 plateaus1 and extinct volcanoes than the famous southwestern region of the ,united ,states4 8,here is something that you will surely recognize without any assistance10 ,i said4 8,in the lower left-hand corner of the picture is the great three-link chain of crater rings1 of which ,theophilus is the principal and most perfect member40 8,oh1 ,i recall them well10 replied my friend4 8,and yet they do not appear to me exactly the same as when ,i saw them before40 ,illustration3 ,,the ,,great ,,southwest ,,on ,,the ,,moon4 8,one reason for that is because this photograph represents them on a much larger scale1 and with infinitely more detail4 ,another reason is that now we are looking at them in the lunar afternoon instead of the lunar morning4 ,we are going to see them represented on a still larger scale1 presently1 but there are many things in this picture well worthy of study4 ,advancing from the west1 the line of night has fallen over the extreme eastern border of the ,mare ,nectaris1 and the shadows thrown by the setting sun point westward4 ,observe how beautifully the brightly illuminated terraces and mighty cliffs of the western wall of ,theophilus contrast with the black shadow that projects over half of the interior from the sharp verge of the eastern wall4 ,the complicated central mountain is particularly well shown4 ,the loftiest peak of this mountain mass1 which covers #cjj square miles1 is #f1jjj feet in height4 ,you will see its shadow reaching the foot of the western wall4 ,theophilus is #fd miles in diameter1 ten miles more than ,tycho1 and it is deeper than ,tycho1 the floor sinking #ah1jjj feet below the top of the highest point on the western wall4 ,if it were the focus of a similar ray system it would deserve to be called the #8,metropolitan ,crater' rather than ,tycho4 ,plainly1 ,theophilus was formed later than its neighbor ,cyrillus1 because the southwestern wall of the latter has been destroyed to make room for the perfect ring of ,theophilus4 8,the interior of ,cyrillus1 you will observe1 is very different from that of ,theophilus4 ,the floor is more irregular and mountainous4 ,the wall1 also1 is much more complex than that of ,theophilus4 ,the broken state of the wall in itself is an indication of the greater age of ,cyrillus4 ,on the south an enormous pass in the wall of ,cyrillus leads out upon a mountain-edged plateau which continues to the wall of the third of the great rings1 ,catharina4 ,this formation seems to be of about the same age as ,cyrillus1 possibly somewhat older4 ,its wall is more broken and worn down1 and the northern third of the inclosure is occupied by the wreck of a large ring4 ,observe the curious row of relatively small craters1 with low mountain ranges paralleling them1 which begins at the southwestern corner of ,cyrillus and runs1 with interruptions1 for #aej miles or more4 ,south of this is a broad valley with small craters on its bottom1 and then comes an elongated mountainous region with a conspicuous crater in its center1 beyond which appears another valley1 which passes round the east side of ,catharina1 where it is divided in the center by a short range of hills4 ,the southeastern side of this valley is bounded by the grand cliffs of the ,altai ,mountains1 which continue on until they encounter the eastern wall of the great ring of ,piccolomini1 whose interior appears entirely dark in the picture1 only a few peaks on the wall indicating the outlines of the ring4 ,the serrated shadow of these mountains1 thrown westward by the setting sun1 forms one of the most striking features of the photograph4 ,the northeastern end of the chain also terminates at a smaller ring named ,tacitus4 ,you see that ,riccioli was rather cosmopolitan in his tastes1 since he has placed the name of a ,roman historian also on the moon4 ,beginning at a point on the crest of the ,altai range1 south of ,tacitus1 is a very remarkable chain of small craters1 which extends eastward to the southern side of a beautiful ring plain with a white spot in the center4 ,this ring is named ,abulfeda4 ,the chain of small craters or pits to which ,i have referred continues1 though much less conspicuous1 across the valley that lies northwest of the ,altais4 ,it is a very curious phenomenon1 and recalls the theory advocated by ,w4 ,k4 ,gilbert1 the ,american geologist1 that the moon's craters were formed not by volcanic eruptions but by the impact of gigantic meteorites falling upon the moon1 and originating1 perhaps1 in the destruction of a ring which formerly surrounded the earth1 somewhat as the planet ,saturn is surrounded by rings of meteoric bodies1 which may eventually be precipitated upon its surface4 ,the moon is more or less pitted with craterlets in all quarters1 but there are places where they particularly abound4 ,on inspecting this photograph carefully you will perceive several rows of much larger pits1 two or three of them in the upper half of the picture1 and one below the center1 crossing the little chain of pits that ,i have just mentioned4 ,the linear arrangement of some of the ring plains is also very striking4 ,in regard to the theory that the lunar craters were formed by the impact of falling masses ,i may mention that two distinguished ,french students of the moon1 ,messrs4 ,loewy and ,puiseux1 have lately expressed the opinion that all of the features of the lunar surface are most readily explicable as the result of causes similar to those which have produced the topography of the earth4 ,if that is so there is no need for us to invoke the agency of meteorites in pitting the surface of the moon4 ,south of the ,altai ,mountains you will see a singular collocation of ring plains and craters which somewhat resemble in their arrangement ,theophilus and its neighbors4 ,first comes a large sunken plain just above the mountains4 ,in fact the ,altai range constitutes the northwestern wall of this formation1 which you may recognize by a conspicuous oval crater near its upper side4 ,above this broken ring appear three other smaller ones1 grouped at the corners of a triangle4 ,the one on the right1 with a central pit and a small ring plain on the inside of its western wall1 is called ,zagut4 ,its close neighbor on the west with most of its interior in shadow1 is ,lindenau1 remarkable for its depth4 ,the most southerly and largest of the group1 with four or five large crater pits forming a curved row across its interior1 is named ,rabbi ,levi4 ,starting from the east side of ,rabbi ,levi there is a long row of similar craters rather larger than those in its interior1 which runs eastward almost to the edge of the photograph4 ,north of these1 parallel with and1 in some instances1 touching the crater pits1 is an equally remarkable row of flat1 smooth1 walled valleys1 which seem to overlap one another on their western sides1 and which increase in size the farther east they go4 ,the largest of these1 with a very irregular wall1 and having a smaller ring with a central peak apparently attached to its northern side1 is ,gemma ,frisius40 ,my friend had listened to me in silence for a long time1 following my finger as it pointed out the various objects on the photograph1 but now she interrupted again3 8,you were pleased to compliment my memory a little while ago10 she said1 8but do you really think that ,i can ever recall all this that you have been saying1 with theories about huge flying stones hitting the moon1 and a string of the strangest names that ,i have ever heard applied to objects that are no less bizarre80 8,pardon me10 ,i replied1 8but you will remember more than you think you will4 ,the very oddity of these ,hebraic and ,arabic names will serve to fix them in your memory1 so that you will at least recognize them when you see them again4 ,those curious objects will also come before your mind's eye whenever you think of1 or look at1 the moon4 ,trust me when ,i tell you that you are forming a better acquaintance with selenography than you are aware of4 ,as to the theory that ,i have mentioned1 what can appeal more powerfully to the imagination than the idea of the moon being bombarded by the fragments of an immense ring falling from the sky8 ,the fact that men of science have believed such a thing possible ought to form a strong appeal to your lively fancy4 ,in any case1 ,i am disposed to be merciless just now1 like a man who has found a patient listener to his hobby1 and ,i am going to trouble you with a few more odd names and singular facts40 8,well10 she replied1 with a sigh1 ending with a smile1 8go on4 ,after all ,i believe ,i am really interested40 8,i am sure you are1 for who could fail to be interested by things so remarkable in themselves1 and so vastly beyond all human experience1 as those that this photograph shows8 ,we stopped at ,gemma ,frisius4 ,let us use that for a new starting point4 ,a considerable distance south1 say about a hundred miles1 is an old friend of ours1 ,maurolycus4 ,it is the large ring plain1 with another half obliterated1 on its southern side1 in the upper part of the picture4 ,notice the row of wrecked rings1 beginning at a great crater on its northeast wall and running westward4 ,the broad1 flat plain directly east of ,maurolycus is ,stfler1 whose name you will also recall4 ,i shall not trouble you with the names of all the rings south of ,stfler and ,maurolycus1 but simply ask you to observe that they form a winding row which leads to a very grand ring almost entirely buried in night1 the inside of its western wall alone being bright with sunshine4 ,this wall1 and some mountain peaks near it1 resemble brilliant islands lying in the edge of the ,cimmerian ocean whose ethereal waves wash the broken coast of the moon4 ,follow the ragged sunset line downward1 and all along you will see these islands of light in the darkness2 tips of mountains still shining while the sun has set upon all the valleys around1 somewhat as you have seen the snowy top of ,mont ,blanc and the pinnacles of its attendant giants glowing after the shades of night have fallen deep upon ,chamounix4 8,look next1 if you please1 at the right-hand side of the photograph4 ,somewhat above the center1 three conspicuous dish-shaped ring plains are seen1 two near together1 the third farther away toward the left and downward4 ,the largest of these is ,aliacensis1 its near neighbor is ,werner1 and the third is ,apianus4 ,they are from #dj to #ej miles in diameter4 ,still lower1 and nearer the middle line of the picture1 is a row of four or five ring plains1 varying from #cj to #dj miles in diameter4 ,the uppermost1 or most southerly of these is double1 or1 in fact1 partly triple1 for the lower member of the pair has a broken plain attached to its southeastern side4 ,this one1 with a small central peak1 is named ,abenezra4 ,its close neighbor on the southwest is ,azophi4 ,you notice the singularity of the names4 ,the next one below1 with a small crater on its east side1 is ,geber4 ,then comes ,almamon1 and finally1 largest of all1 ,abulfeda1 which ,i pointed out to you as marking the end of the curious row of little crater pits1 running eastward from the ,altai ,mountains4 ,there is just one other formation to which ,i wish to call your attention in this remarkable photograph1 and then we shall turn to the next in the series4 ,west of ,abenezra and ,azophi1 about half way to the ,altai ,mountains1 you will notice a very irregular depression with three strongly marked craters within it4 ,this bears the name of ,sacrobosco1 an old-time astronomer4 ,its eastern wall with its shadow looks like an elongated letter ,w standing on end4 ,sacrobosco and its surroundings constitute one of the most intricate regions on the moon1 high plateaus alternating with great sunken valleys1 rings1 craters1 and crater pits4 ,the wall of ,sacrobosco is extremely irregular in height1 shooting up in some places with peaks of #ab1jjj feet elevation1 and sinking in others almost to the level of the surrounding plateaus40 ,we now took up the next photograph representing ,theophilus and its companions on a greatly enlarged scale4 ,my friend uttered a cry of astonishment upon seeing it4 8,dear me10 she exclaimed1 8the moon becomes more terrible every moment6 ,positively1 ,i almost shrink from the sight40 ,illustration3 ,,the ,,giant ,,ring ,,mountains1 ,,theophilus ,,and ,,its ,,neighbors4 8,yes10 ,i assented1 8it surely is terrible here4 ,in a little while1 however1 ,i shall show you a lunar scene of surpassing beauty4 ,but study this spectacle with an inquiring mind and you will find that it1 too1 has its attractions4 ,you are now looking upon ,theophilus1 ,cyrillus1 ,catharina1 and the surrounding region as the astronomer sees them with the most powerful telescopes4 ,indeed1 with the telescope he sees the details more sharply than they are visible here1 for the best photographs still lack something in distinctness4 ,the illumination when this picture was taken was practically the same as in the last that we examined1 but the magnification is much greater4 ,look1 now1 at the central mountain in ,theophilus4 ,its great buttresses cast their shadows into profound ravines and chasms1 imparting to it a most singular outline4 ,observe the tooth-shaped shadows of its two principal peaks1 thrown westward across the floor1 while the broad shadow of the western wall emphasizes the immense depth of the depression4 ,the glare of the afternoon sun on the cliffs of the inner side of the eastern wall is so brilliant that the details are obscured4 ,but the surface of the moon outside1 particularly toward the north and the west1 is beautifully brought out with all its wonderful modulations and irregularities4 ,judging by appearances1 those who hold that ,theophilus and similar formations1 notwithstanding their enormous magnitude1 are really of volcanic origin1 have the strongest reasons for their opinions4 ,immense flows of lava seem to have taken place on all sides of the great ring1 entering the ,mare ,nectaris on the west4 ,notice the huge mountain fold which runs from the parallel ridges on the southwestern side of ,theophilus to the crater ring ,beaumont1 lying west of ,catharina4 ,observe1 also1 the complicated form of the wall dividing ,theophilus and ,cyrillus4 ,two deep ravines1 shown by the shadows that fill them1 cross one another like the arms of a flat letter ,x4 ,one of these ravines turns northward along the wall and re-enters ,theophilus1 while the other continues for a long distance within the western side of ,cyrillus4 ,i cannot imagine a more interesting or a more stupendous excursion for a geologist1 a mountaineer1 or a seeker after wonderful and sublime aspects of nature1 than a climb around the crest of the wall of ,theophilus--if indeed such a climb can be regarded as humanly possible4 8,now1 again1 ,i am reminded of what ,i once told you about the amazing contrasts of light and darkness1 and of heat and cold1 upon the moon4 ,suppose yourself standing on the verge of the eastern wall of ,theophilus where the edge seems sharpest1 and looking down into the abyss at your feet4 ,the sun's rays would be unbearably hot where they touched your face and hands1 but if you let yourself down a little way into the blackness beneath you would not only pass instantly into night1 but you would shiver and shrink with cold so frightful that no winter experience that you have ever had could give an idea of its intensity4 ,from that point of observation you would look across a chasm of inky darkness1 #be miles broad1 and see1 towering up from the illuminated plain afar off1 with their summits more than two miles below your level1 the brilliant group of the central peaks1 while behind them the crest of the western wall would appear like a bright line on the horizon #fj miles away4 ,changing your place to one of the peaks on the dividing wall you would look down into ,theophilus on one side and ,cyrillus on the other4 ,then upon lifting your eyes to the black1 airless sky you would see the stars sparkling on all hands1 and1 hanging in the heavens like a portentous1 strangely colored moon many times larger than the disk of the sun1 would appear the mottled orb of the earth4 ,the terrific nature of the scenery around you1 the meeting of day and night at your feet1 and the incredible blending together of their characteristic aspects in the sky above you1 the startling magnitude of the suspended earth--all these things combined would make you feel as if you were not only in another world but in another universe40 8,i no longer wish to visit the moon10 interrupted my friend1 shaking her head4 8,not if you were assured of a safe return80 8,no1 it would upset my mind4 ,i am certain that ,i should go crazy in such a world where everything seems to be topsy-turvy40 8,wait until we arrive at the #8,sea of ,serenity' once more1 and perhaps you will think better of it4 ,notwithstanding the increased magnification1 the details in ,cyrillus and ,catharina are hardly better seen in this photograph than in its predecessor1 but the increase of size is very effective in emphasizing some of the features of the surrounding district4 ,cyrillus is seen to have a decided hexagonal outline1 and west of its southern corner is an exceedingly curious formation1 approaching closely to a square shape4 ,the wall is illuminated within on all four sides1 and out of the midst of the lozenge-shaped shadow resting over the bottom of the included valley1 rises a mountain which1 like the walls1 is bright with sunshine4 ,on the southwest a semicircular ridge runs out into the darkness1 its top brightly illuminated4 ,the general effect of the entire formation is fantastic4 ,and could you imagine a wilder scene than that presented by the elongated mountain mass1 which starts from the southwestern side of ,cyrillus1 skirts the border of ,catharina1 and continues on along the northwestern side of the broad valley in the upper part of the picture8 ,see how it has1 apparently1 been rent apart by tremendous forces and torn by volcanic outbursts1 which have left yawning craters everywhere4 ,even the valley itself seems to be simply a chain of wrecked crater rings of vast size1 the cross walls having nearly disappeared4 ,observe1 too1 the immense number of crater pits of all sizes scattered everywhere1 both inside the ring plains 7,theophilus alone having few of them7 and over the surrounding country4 ,we shall see a still more remarkable example of this pitting of the lunar surface in the neighborhood of ,copernicus1 which is the chief object in the next photograph that we take up40 ,we came now to the large picture of ,copernicus1 and my friend took it in her hands to examine it4 8,it is a marvelous thing to look upon10 she said1 8but it doesn't frighten me as ,theophilus did40 8,no1 ,copernicus is rather sublime than terrifying in aspect4 ,its comparatively lone situation1 with the ,mare ,nubium1 the ,oceanus ,procellarum and the ,mare ,imbrium surrounding it on all sides with their broad1 level expanses1 gives it an appearance of solitary grandeur belonging to no other single formation on the moon4 #8,the monarch of the lunar ring mountains1' ,mr4 ,elger has termed it4 ,first let me tell you the principal facts known about ,copernicus4 ,it is #ef miles in diameter1 two miles more than ,tycho1 and eight less than ,theophilus4 ,it is not as deep as either of those formations1 the highest points on its walls being #ab1jjj feet4 ,but the walls are more uniform in height than is usual with so extensive a ring4 ,they are very steep on the inside1 especially near the top1 where their slope has been estimated by ,neison at from #ej to #fj4 ,to a person standing on their verge they would seem almost perpendicular4 ,the central mountain consists of five principal peaks4 ,the outer slopes of the ring are also steep1 but its maximum height above the surrounding surface does not exceed #c1jjj or #d1jjj feet1 so that ,copernicus1 like the other great ring mountains1 is1 in reality1 a vast sink1 encircled with a mountain ridge4 ,you will note that ,copernicus clearly exhibits the tendency to a hexagonal form which we have observed elsewhere1 although it stands alone with no other great rings pressing against its walls4 ,curiously enough the form of ,copernicus is very closely repeated in the small crater ring ,gay ,lussac1 situated in the mountains on the lower 7north7 side4 ,this picture1 ,i should remark1 unlike the last two preceding it1 was taken near lunar sunrise1 and accordingly the light comes from the west4 ,this is the best illumination for studying ,copernicus and its vicinity4 ,of all the great ring plains ,copernicus perhaps gives the most striking testimony in favor of the view of those who hold that the lunar volcanoes were once the actual centers of volcanic action1 resembling the volcanoes of the earth in the ejection of vapors1 ashes1 stones1 and streams of lava4 ,the slopes around ,copernicus for many miles look as though they had been covered with lava and pitted with minor craters such as appear on the shoulders and in the vicinity of many of our volcanoes1 while the appearance of the great ring does not contradict the theory of ,nasmyth and ,carpenter1 which ,i have previously mentioned1 that it was built up by ejections from a central crater now more or less completely filled4 ,as ,i have already told you the lunar volcanoes differ essentially from those of the earth in that their central depressions lie deep beneath the level of the surrounding surface of the moon4 ,this is strikingly true of ,copernicus1 and it is a result that might have been foreseen from the enormous size of the craters4 ,a mountain of sufficient magnitude to carry the vast cup of ,copernicus on its head1 as ,vesuvius1 ,etna1 ,cotopaxi1 and ,popocatepetl carry their craters1 could not stand even on the moon4 ,observe the generally radial arrangement of the lines about ,copernicus1 recalling the similar arrangement of lava flows about terrestrial volcanoes4 ,some of these lines1 as you will see1 consist of long rows of pits4 ,similar phenomena may be seen along the lava streams that we are familiar with on our planet1 where small craters break forth one after another4 ,a striking example of this arrangement is visible in the photograph on the northeastern slope leading up toward the ,copernicus ring4 ,but you will also see many very remarkable rows of pits in the vicinity of ,copernicus which are not radial in arrangement with respect to the ring4 ,the most conspicuous of these is on the northwestern side1 about half way between ,copernicus and the ring of ,eratosthenes1 which standing at the upper end of the chain of the ,apennines appears at the left-hand edge of the picture4 ,there are hundreds1 probably thousands1 of these pits on all sides of ,copernicus4 8,one of the explanations that has been suggested for them is that they were produced by the fall of enormous volcanic bombs thrown from ,copernicus when it was in eruption4 ,i wish merely to mention this idea without comment4 ,it however calls up another interesting theory1 which has not met with much acceptance1 to the effect that such lunar volcanoes as ,copernicus may have been powerful enough to eject masses of lava and rocks with a velocity sufficient to enable them to escape from the attraction of the moon1 whereupon they became meteorites traveling in independent orbits around the sun4 ,some of these1 the theory suggests1 may be among those that have fallen upon the earth4 ,a velocity of a mile and a half per second would be sufficient to overcome the gravitation of the moon4 ,that is only three or four times the initial velocity which some modern guns are capable of imparting to their projectiles40 8,i am sorry10 explained my friend1 8that you seem to attach little importance to so interesting a theory4 ,it stirs my imagination to think of the moon sending bits of herself back to her mother planet4 ,for my part1 the theory does not seem to be any harder to believe than that of your ,professor ,darwin that the whole moon was thrown off from the earth4 ,besides1 it intensifies my appreciation of the grandeur of ,copernicus when ,i am told that that great volcano could once bombard the earth across--what is it1 #bdj1jjj miles8--of space40 8,as you always choose the most picturesque theories to rest your belief upon1 ,i shall not complain if you accept the lunar volcano theory of meteorites10 ,i replied4 8,but1 for the present1 we have done with it1 and ,i am now going to ask you to inspect the photograph for other interesting objects4 ,east and north of the great ring you will see an extensive mass of mountains4 ,those on the north1 with immense buttresses projecting into the ,mare ,imbrium1 are the lunar ,carpathians4 ,i have already directed your attention to a comparatively small crater ring which resembles a reduced copy of ,copernicus1 situated in these mountains at the head of a bay which penetrates southward between high ridges1 for about #cj miles4 ,this crater is named ,gay ,lussac4 ,it has a small deep neighbor on the southwest4 ,west of ,gay ,lussac the ,carpathians gradually dwindle away until they sink to the level of the plain4 ,toward the east they project in several bold headlands1 terminating with towering peaks into the #8sea4' ,lying off the point of the headland on the western side of the bay that leads to ,gay ,lussac you will perceive two charming little craters1 almost perfect twins4 ,much farther toward the north and west is a larger crater1 more than half of whose interior is black with shadow4 ,this is ,pytheas4 ,its lonely situation is very striking1 but upon close inspection you will notice that a low range of hills appears to connect it with the twin craters that ,i have just pointed out4 ,this range of hills1 lying on the #8sea' bottom1 is curiously forked1 the other branch leading to a pair of small peaks in the #8sea1' which possess no craters4 ,the little crater east of ,pytheas is also a beautiful object in the picture4 8,near the eastern end of the ,carpathians the mountains make their greatest advance into the ,mare ,imbrium1 leaving a large square-cornered bay on the west4 ,from this point they turn southward1 forming a complicated mass of peaks and ridges interspersed with craters and pits4 ,these mountains east of ,copernicus are among the most singular upon the moon1 for they inclose a group of irregular-shaped plains1 the walls of which consist of immense1 more or less separate1 masses4 ,look at the one nearest to ,copernicus1 which has somewhat the form of a starfish1 and observe how curiously its southern border reflects1 on a smaller scale1 the forms characteristic of the headlands and bays along the shore of the ,mare ,imbrium below4 8,above ,copernicus you see a large crater ring more than half in shadow1 with a plain of an irregular hexagonal shape1 northwest of it4 ,the large ring is named ,reinhold4 ,a broken mass of mountains extends from its southern side far into the ,mare ,nubium4 ,in the upper right-hand corner of the picture is another large ring called ,landsberg4 ,in the upper left-hand corner you see a roughly hexagonal ring plain1 level on the interior1 named ,gambart4 ,mountains break the level of the mare both south and north of ,gambart4 ,those on the north are remarkable for the darkness of the surface1 especially in the northwestern part4 8,almost directly west of ,copernicus lies an exceedingly singular object4 ,it is a part of the underworld of the moon1 the buried moon1 which was covered up ages ago by that immense outgush of lava of which ,i have so often spoken4 ,once evidently it was a ring larger than ,eratosthenes4 ,now1 only its outlines can be traced1 the whole immense depression of the interior and the surrounding walls to their very top having been covered up4 ,it is pitted and surrounded with little craters of a later date4 ,i have already told you that ,eratosthenes1 the ring at the left-hand edge of the photograph1 marks the termination of the great range of the lunar ,apennines4 ,but these mountains seem to be continued beyond ,eratosthenes in two short branches1 one turning eastward toward the ,carpathians1 and the other reaching to the highest part of the buried wall of the submerged ring that we have been talking about and which bears the name of ,stadius4 ,you will be interested in knowing that southwest of ,stadius1 but off the edge of the picture1 there is a place in which low hills and ridges abound1 where the ,german astronomer ,schrter imagined that he had discovered a lunar city6 ,his mistake was1 perhaps1 natural1 considering the slight power of his telescope and the strangely regular arrangement of the lines of hills which he mistook for streets40 8,i regret that he was deceived40 ,illustration3 ,,two ,,great ,,lunar 8,,seas0 ,the ,mare ,serenitatis and a ,part of the ,mare ,imbrium4 8,so do ,i4 ,we shall now leave ,copernicus and its marvelous surroundings1 and turn to the last photograph in our series1 representing the ,mare ,serenitatis in its full extent1 and a large part of the ,mare ,imbrium4 ,is it not a beautiful picture80 8,it is1 indeed1 but so strange60 8,there is1 ,i believe1 nothing in the lunar world that would not seem strange to our eyes4 ,to understand just what this picture means you should imagine yourself floating in an airship at an immense height above the surface of the moon4 ,the ,mare ,serenitatis you will recognize as the great oval plain occupying the upper left-hand part of the photograph4 ,it is entirely encircled by mountains except in three places--at its eastern end1 where a broad strait opens between the ,apennines on the south and the ,caucasus on the north1 leading into the ,mare ,imbrium2 on the northwest1 where another strait opens into the ,lacus ,somniorum1 the #8,lake of the ,sleepers1' or #8,the ,dreamers1' and on the southwest1 where a third strait with a conspicuous crater in its center leads into the ,mare ,tranquillitatis4 ,the ,mare ,serenitatis is #dcj miles long and nearly as broad1 and covers an area of about #abe1jjj square miles4 ,a great many details are visible on its floor4 ,even if it were covered with water we might see these1 for1 as you have probably heard1 the bottom of deep lakes is visible when one looks down upon them from a great height4 ,the surface of water1 however1 at certain angles of view and of illumination1 would produce flashes and glares of light which are never seen on this vast lunar plain40 8,oh1 but it must once have been a sea10 said my friend1 poring over the photograph4 8,i cannot give up that idea4 ,it gives the interest of life to the moon1 if not now at least in the past40 8,you are by no means compelled to give up your idea10 ,i replied4 8,on the contrary you are supported by the opinion of many astronomers1 including ,messrs4 ,loewy and ,puiseux1 whom ,i quoted a little while ago4 ,they aver that the resemblances between the lunar mares and the beds of our terrestrial oceans are too numerous and too decided to permit any other conclusion than that in the one case as in the other a deep covering of water has produced the characteristic features4 ,one striking resemblance that they note is in the surface contours4 ,the lunar sea beds are generally deepest along the shores2 the same is true of the terrestrial seas4 ,continents on the other hand are characterized by concave surfaces4 ,but before we study the two lunar #8seas' in detail let us first look at their shores and surroundings4 ,the upper and right-hand sides of the ,mare ,serenitatis are bordered by hundreds of miles of magnificent cliffs1 which in many places are very steep and of great height4 ,these form what we may call the sea front of the ,hmus ,mountains1 which join the lunar ,apennines on the southern shore of the strait leading into the ,mare ,imbrium4 ,these mountains possess one conspicuous crater1 set like a gem in the chain1 at about a third of its length from the western end4 ,this crater is ,menelaus1 which we saw in one of the smaller photographs4 ,it is characterized by its exceptional brilliance as well as by the fact that the longest of the bright bands that start from ,tycho passes through it1 and then continues on across the ,mare ,serenitatis and the ,lacus ,somniorum1 to the ,mare ,frigoris4 ,this band1 more than #b1jjj miles long1 has come all the way from ,tycho1 high in the southern hemisphere1 never turning aside to avoid anything in its path4 ,mountains1 craters1 and ring plains are equally indifferent to it4 ,it is like a ,roman road1 and like that1 too1 it suggests for its creation a power that knew no master1 and admitted of neither rivalry nor opposition4 ,the existence of this mysterious band increases the difficulty of finding a satisfactory explanation of the ,tychonic rays4 ,in the midst of the mare the band or ray crosses another lone crater1 #ad miles in diameter1 named ,bessel4 ,the full length of the ray is not shown in this photograph1 but on its way from ,bessel it touches two other small craters in the #8sea4' 8,that portion of the ,hmus range in which ,menelaus is set is a very attractive scene on account of the bow shape of the mountains1 and the situation of the bright crater just in the center of the bow4 ,menelaus and the streak from ,tycho can be seen at ,full ,moon with no greater optical aid than that of a good binocular4 ,on the edge of the #8sea1' off a lofty headland of the ,hmus chain1 another lone little crater is visible1 ,sulpicius ,gallus by name4 ,it1 too1 is remarkable for its brilliant reflective power4 ,behind the mountains1 directly back of ,sulpicius ,gallus1 and lying in an upraised part of the ,mare ,vaporum1 is a larger1 and even brighter1 crater ring than ,menelaus4 ,it is named ,manilius1 and is likewise a conspicuous object for a binocular at ,full ,moon4 ,below ,sulpicius ,gallus the ,hmus ,mountains broaden out and assume a curious somber tone1 until1 in the form of a rough plateau1 they blend with the wide-expanded southwestern slopes of the ,apennines4 ,the latter rise gradually to the chain of huge peaks fronting the ,mare ,imbrium4 ,they contain one notable crater ring named ,marco ,polo1 which lies just above a great square massif1 which breaks the narrow chain of the illuminated summits of the ,apennines4 ,the precipitous front of this range appears very brilliant in the afternoon sun1 for here again we have a photograph made after the time of ,full ,moon4 ,the end of the ,apennines touching the strait1 of which ,i have previously spoken1 terminates with a high cape called ,mount ,hadley4 ,in the strait1 off this cape1 is an array of small mountain peaks1 which must have been islands1 if the lunar #8seas' were once true seas4 8,across the strait1 on the northern side1 stand the lunar ,caucasus ,mountains4 ,they run out to a point in a long1 irregular1 broken ridge4 ,the distance from ,mount ,hadley across the strait to the projecting point of the ,caucasus range is about #ej miles4 ,the islands narrow the main opening to a width of #cj miles4 ,in strict fact the ,caucasus range is not continuous4 ,the point fronting the strait is1 in reality1 the end of a large irregular #8island1' with intricate channels separating it from the mainland4 ,still farther north the photograph shows a broad valley severing the mountain range from side to side4 ,the main mass of the ,caucasus continues northward to the great ring mountains ,eudoxus and ,aristoteles4 ,in the center of the range1 opposite the lower corner of the ,mare ,serenitatis1 is an irregular ring plain1 ,calippus4 ,west of this the mountains break down in great precipices to the level of a plain that might be compared with one of the #8parks' of ,colorado4 ,beyond this1 in the shape of a broad mass of hills1 it skirts the border of the ,mare ,serenitatis for nearly #bjj miles to a sharp promontory which shuts off the ,lacus ,somniorum on one side from the mare4 ,west of ,aristoteles and ,eudoxus the mountain mass extends to a curious sharp-angled plain1 which it skirts on the north and south4 8,the western shore of the ,mare ,serenitatis beyond the strait opening into the ,lacus ,somniorum is bordered by a series of alternating ring plains and connecting mountains4 ,the first and largest of the rings is ,posidonius1 an immense formation #fb miles in diameter1 with a central crater and curious ridges within the inclosure4 ,above ,posidonius is ,le ,monnier1 a ring plain whose #8seaward' wall has been broken down4 ,above that1 again1 is a mountain range terminating with broken crater rings4 ,then we arrive at the strait opening into the ,mare ,tranquillitatis1 which is twice as broad as that between the ,apennines and the ,caucasus1 and just in the middle of it stands a very perfect crater ring named ,dawes4 ,on the eastern side of this strait the ,hmus ,mountains begin with a long cape called the ,promontory ,acherusia4 ,above this promontory1 at the edge of the picture1 appears the ring plain ,plinius1 with a distinct central peak4 ,this completes the circuit of the ,mare ,serenitatis4 8,we return to the ,caucasus region4 ,these mountains front the ,mare ,imbrium along the upper part of their course with sharp slopes and cliffs4 ,in the #8sea1' nearly opposite the deep1 broad valley which ,i pointed out as dividing the range completely across1 stands a triangular-shaped ring plain dark with shadow on one of its sides4 ,this is ,thetetus1 interesting as the scene of an alleged display of #8smoke1' reported to have been witnessed by a ,french observer with his telescope a few years ago4 ,several occurrences of this kind have been reported on the moon1 but more or less doubt attaches in every instance the accuracy of the observations1 or at least to that of the conclusions drawn from them4 ,below ,thetetus is an oval ring almost entirely filled up1 with two craters within it4 ,this is named ,cassini4 ,below ,cassini begins another mass of mountains1 the lunar ,alps4 ,these are by no means as extensive as the ,caucasus1 but they contain some lofty peaks1 and are traversed by one of the most remarkable valleys on the moon4 ,it is not very distinctly shown in this picture1 but you may recognize it by a dark band commencing opposite a small bay which sets back into the mountains4 ,the valley continues through the mountains and the adjoining hilly regions nearly to the shore of the narrow ,mare ,frigoris1 which runs in a sloping direction from beyond ,aristoteles to the bottom edge of the picture4 ,the ,alps spread eastward1 broadening out with many separate peaks1 and skirting the ,mare ,imbrium1 until they reach one of the most singular and interesting of lunar formations1 the oval ring plain ,plato4 ,this looks like a dark lake surrounded by high cliffs4 ,in the photograph all of the encircling wall is illuminated on the inner side except at the east end1 where the shadows extend a short distance upon the floor4 ,plato looks as though it might once have been a ring mountain of the usual type1 which has been partly filled in the interior by a local uprush of molten lava4 ,the diameter of the ring is #fj miles1 but the inclosure sinks only about half as deep beneath the crest of the wall1 as is the rule with formations of similar outline4 ,a central peak1 a group of mountains1 may be buried there4 8,it is within this ring of ,plato that some of the strongest evidences of continued change1 and possibly of continued life upon the moon1 have been found4 ,prof4 ,william ,h4 ,pickering1 after long and careful studies of this remarkable plain1 says of it3 8#8,plato is1 ,i believe1 more active in a volcanic sense than any area of similar size upon the earth4 ,there seems to be no evidence of lava1 but the white streaks indicate apparently something analogous to snow or clouds4 ,there must be a certain escape of gases1 presumably steam and carbonic acid1 the former of which probably aids in the production of the white markings4' 8,the white marks to which ,professor ,pickering refers are but faintly indicated in the photograph before us1 but with the telescope1 when the illumination is favorable1 they are plainly seen4 ,there are a number of very small crater pits scattered over the floor of ,plato1 and around these changes of color occur which have been ascribed to the emission of some substance from the pits and to the presence of vegetation1 nourished by the gases and vapors1 and springing into renewed life every time the sun rises upon the plain4 ,broad areas of the inclosure gradually change color as the sun rises1 and again as the sun sets1 and these phenomena have also been ascribed to the presence of vegetation4 ,you may1 if you wish1 regard ,plato as a kind of mountain-ringed prairie1 covered with something analogous to prairie grass and shrubs1 which depends for its existence1 partly1 upon the supply of gases spreading over the surface from the crater pits40 8,so this1 then1 is your #8lunar grass'80 8,yes1 but not all of it4 ,mark1 ,i do not aver that it actually exists2 ,i only say that it has been suspected to exist4 ,on some of the mares similar appearances are seen1 as ,i have already told you1 on a much more extensive scale1 and ,i may again quote ,professor ,pickering1 who says that some of his observations #8point very strongly to the existence of vegetation upon the surface of the moon in large quantities at the present time4'0 8,does this vegetation resemble that of the earth80 8,i cannot tell you40 8,but where vegetation exists animal life is possible1 is it not80 8,yes1 it is possible40 8,what forms would it have80 8,i cannot tell you4 ,but ,i certainly should not expect to find manlike creatures there40 8,oh1 men are not necessary everywhere10 said my friend1 laughing4 8,i am content if you admit that there may be living creatures of some kind4 ,henceforth ,i shall never forget ,plato and the other places on the moon where such significant changes are seen40 8,i shall presently point out to you one of the most notable of those other places10 ,i replied4 8,let me now fulfill my promise to tell you more about the lunar atmosphere4 ,i have told you already that there are strong reasons for supposing that the moon once had a far more dense atmosphere than she possesses at present1 and ,i have mentioned some of the ways in which this atmosphere is supposed to have disappeared4 ,i think that it is worth our while to refer to them again4 ,in the first place the moon's atmosphere may have been withdrawn into vast internal cavities formed by the gigantic volcanic eruptions4 ,secondly1 it may have been absorbed both mechanically and chemically by the core of the moon as it cooled off4 ,we know that cooling rocks absorb immense quantities of the gases constituting the air we breathe4 ,in fact we may look forward to a time1 fortunately for us extremely remote1 when the interior rocks of the earth will1 in this manner1 absorb perhaps all of its atmosphere40 8,but if the air of the moon has gone into great cavities in the interior1 why might not the living beings of the moon have followed it there80 8,according to some of the theorists10 ,i answered1 8that may really be what has occurred1 and thus the moon has become a #8cavern world' on a gigantic scale4 ,but science does not regard seriously these speculations about #8cave life' in the moon4 ,a third hypothesis is that which ,i have mentioned concerning the escape of the atmospheric gases from the moon on account of its attraction being insufficient permanently to retain them4 ,this process would be gradual1 because the molecules of a gas fly in all directions1 only a small proportion having their trajectories directly away from the center of the globe on which they are held4 ,but a singular consequence of this theory is that interplanetary space must contain an enormous number of such wandering molecules1 and every attracting body must draw more or less of them to its surface1 thus forming an atmosphere for itself4 ,as ,professor ,young has remarked1 if as many of these molecules enter a planet's atmosphere in a day as escape from it there can be no decrease of the total amount of air4 ,if more escape than enter1 the atmosphere will diminish4 ,if more enter than escape1 the atmosphere will grow4 ,finally if none escape the atmosphere may increase indefinitely4 ,this1 as far as the effect of gravitation is concerned1 should be the case on the sun1 for the solar attraction is more than sufficient to retain any gas known to us4 ,in consequence1 the sun's atmosphere may be increasing in extent and density4 ,even the earth's atmosphere may be slowly increasing from this cause1 and herein may lie the explanation of the enormous atmosphere surrounding the great planet ,jupiter4 8,in view of what ,i have said it is evident that the moon cannot be entirely airless4 ,recent observations have confirmed this conclusion1 and some observers have thought that they could detect the presence of something resembling clouds occasionally creeping like low fogs over certain places on the moon4 ,all this1 you will observe1 has an important bearing upon the question of life on the moon at the present day4 ,certain forms of plant life and low animal organizations might exist in such an atmosphere as the moon still possesses40 8,but10 interjected my friend1 8is not this that you have been telling me in contradiction to what you said about the cause of the sharp division between day and night on the moon1 and about the visibility of the stars there in the daytime80 8,not at all10 ,i replied1 8for the effects of which ,i spoke are relative4 ,in any case the atmosphere of the moon must be too rare to diffuse any perceptible amount of light into the shadows1 or to illuminate the sky sufficiently to render the stars invisible4 ,the same reasoning applies to what ,i have told you about the contrasts of cold and heat on the moon4 8,but we have not yet finished with our photograph4 ,we were looking at the plain of ,plato1 you will recollect4 ,notice1 now1 the ,mare ,imbrium off the coast that adjoins ,plato on the south4 ,you see there several bright spots resembling islands4 ,islands they must have been if the mare once had water covering it4 ,one of these1 standing by itself1 an irregular1 bright clump with a distinct shadow on the western side1 bears the name of ,pico1 taken from the sharp peak in the ,azores ,islands4 ,the broken mass southeast of ,pico1 and nearer the coast1 constitutes the ,teneriffe ,mountains4 ,you will notice that terrestrial geography has been drawn upon in this case also to supply a name4 ,still farther east is a long #8island' named the ,straight ,range4 ,beyond that1 at the edge of the picture1 appears ,cape ,laplace1 at the western end of the #8,bay of ,rainbows4' 8,we now turn to the southwestern border of the ,mare ,imbrium1 in the upper part of the photograph4 ,this1 as ,i have already pointed out1 is skirted by the steep cliffs of the ,apennines for a distance of more than #djj miles4 ,opposite the crater ring ,marco ,polo1 in the ,apennines1 you will notice how the floor of the #8sea' is upheaved1 containing a great number of irregularities1 and some small peaks4 ,this would have been a dangerous part of the #8,sea of ,rains' for the lunar navigators4 ,at the northwestern corner of this region lies a large ring plain1 with indefinite light stripes crossing its floor1 which is named ,archimedes4 ,it is about #ej miles in diameter4 ,northwest of it are two smaller ring mountains1 ,aristillus 7the larger7 and ,autolycus4 ,if we could suppose these immense volcanoes to have been in eruption when these seas were navigable1 imagine the magnificent spectacle that they would have presented to anyone approaching in a ship from the direction of the strait between the ,apennines and the ,caucasus4 8,let us now pass this strait and enter the ,mare ,serenitatis4 ,you will admire the beautiful modulation of the bottom1 as shown in the photograph4 ,lighter and darker regions are curiously interspersed1 and in some places there are faint indications of that wonderful lunar world of remote antiquity which lies buried in the grave of a planet4 ,directly opposite the opening of the strait1 a small1 round1 light spot is seen in the midst of the sea4 ,this is ,linn1 very famous for its strange and suggestive history4 ,here1 if anywhere on the moon1 changes visible to human eyes have taken place1 and1 in the opinion of ,professor ,pickering1 are still taking place every fortnight4 ,in the center of the light spot is a minute crater1 and from this crater there seems to issue some kind of vapor which spreads over the surrounding surface1 alternately expanding and shrinking in extent4 ,a remarkable change in the form and appearance of ,linn was recorded by the astronomer ,schmidt1 at ,athens1 in #ahff4 ,what had occurred has been explained by some as the falling in of a crater floor some six miles in diameter4 ,but the observations of ,professor ,pickering are more interesting and suggestive4 ,according to him the bright patch about the crater pit extends during the lunar night and diminishes by day1 indicating that something issues from the pit and is deposited over the surrounding plain in the form of hoar frost1 which melts away in the sunshine4 ,he has even recorded an apparent expansion of the white area during a lunar eclipse when the cold shadow of the earth tends to condense the vapors4 ,if this is true it seems rather surprising that many more similar phenomena are not visible elsewhere4 8,among the most remarkable and beautiful features of this photograph are the winding ridges like half-submerged mountain ranges that appear on the sea bottom in various places4 ,notice particularly the long twisted chain that lies across the western part4 ,between this and a shorter range1 close to the west shore1 runs a broad1 dark valley1 with the crater ,dawes lying in the middle of it at the upper end4 ,some of these winding ridges suggest by their shape and modulation the action of water4 ,finally1 let us return to the strait through which we recently passed4 ,notice that the ,apennines and the ,caucasus look as though they had once formed a continuous line of mountains1 which has been broken through in its center1 leaving huge buttresses on each side1 like the ,pillars of ,hercules at the ,strait of ,gibraltar80 8,that place has an irresistible attraction for me10 said my companion4 8,i cannot withhold my imagination from picturing the scene there when the waters rolled deep over those great bottoms1 and when white-sailed ships were passing and repassing between the towering capes1 carrying the commerce of opulent cities situated along those marvelously picturesque shores40 8,perhaps10 ,i suggested1 8the lunarians1 whom you have reconstructed in your fancy1 reached1 before the catastrophe came that ended their existence1 a higher state of civilization than ours1 and learned to substitute electrically driven vessels for white-winged ships40 8,that would be like the introduction of vulgar steamboats on the canals of ,venice10 she replied4 8,well10 ,i said1 8this ends our survey and one month of photographic journeying on the moon1 and ,i am glad that you have finished it with so pleasing a vision40 99 99 99 99 99 ,upon parting from my friend ,i left the photographs in her possession4 ,a few weeks later ,i received a letter from her in which she said3 8,i have been studying and restudying those wonderful pictures of the moon4 ,i have ordered a telescope to be set up in my park near the elm1 and when it is ready ,i wish you to come and instruct me how to view the moon for myself4 ,i believe that ,i am becoming a learned and enthusiastic selenographer1 and those strange names--,gemma ,frisius1 ,bullialdus1 ,abulfeda1 ,abenezra1 ,rabbi ,levi1 ,maurolycus1 ,fra ,mauro1 ,sacrobosco1 ,zagut1 ,cichus1 ,sulpicius ,gallus--have established their fascination over my mind4 ,theophilus no longer terrifies me with its formidable aspect1 and ,i spend hours poring over the ,mare ,serenitatis4 ,but my fancy remains faithful to the #8,marsh of a ,dream1' which still represents for me the culmination of lunar ideality4 8,as to life on the moon1 ,i find that ,i cannot be satisfied with a mere grass theory4 ,i am so well convinced that there must be something more1 that ,i no longer relegate my lunarians to an age antedating the volcanoes4 ,on the contrary1 as soon as ,i get my telescope ,i am going to look for signs of them and their doings in the present day1 and willy nilly1 sir1 you have got to aid me in the search40 ---------------------------------------- -------------------------------- ,,appendix ---------------------------------------- -------------------------------- ,,appendix ,,dates1 and age of the moon1 when the twenty-one serial photographs were made at the ,yerkes ,observatory1 by ,mr4 ,wallace1 with the #ab-;inch telescope and a special color filter constructed by him3 ,no4 #a1 ,february #ai1 #aijd2 ,moon's ,age #c4he ,days ,no4 #b1 ,september #bd1 #aijc2 ,moon's ,age #c4hg ,days ,no4 #c1 ,july #bi1 #aijc2 ,moon's ,age #e4ed ,days ,no4 #d1 ,november #bd1 #aijc2 ,moon's ,age #e4gd ,days ,no4 #e1 ,july #a1 #aijc2 ,moon's ,age #f4bd ,days ,no4 #f1 ,november #bf1 #aijc2 ,moon's ,age #g4ge ,days ,no4 #g1 ,july #b1 #aijc2 ,moon's ,age #g4bd ,days ,no4 #h1 ,august #ca1 #aijc2 ,moon's ,age #i4bb ,days ,no4 #i1 ,august #b1 #aijc2 ,moon's ,age #h4ig ,days ,no4 #aj1 ,november #cj1 #aijc2 ,moon's ,age #aa4gh ,days ,no4 #aa1 ,december #a1 #aijc2 ,moon's ,age #ab4ih ,days ,no4 #ab1 ,september #d1 #aijc2 ,moon's ,age #ac4bg ,days ,no4 #ac1 ,september #e1 #aijc2 ,moon's ,age #ad4dj ,days ,no4 #ad1 ,august #bf1 #aijd2 ,moon's ,age #ae4fe ,days ,no4 #ae1 ,august #bh1 #aijd2 ,moon's ,age #ag4da ,days ,no4 #af1 ,august #bi1 #aijd2 ,moon's ,age #ah4fb ,days ,no4 #ag1 ,october #aj1 #aijc2 ,moon's ,age #bj4jf ,days ,no4 #ah1 ,september #bi1 #aijd2 ,moon's ,age #bj4ej ,days ,no4 #ai1 ,august #af1 #aijc2 ,moon's ,age #bc4ha ,days ,no4 #bj1 ,august #ag1 #aijc2 ,moon's ,age #bd4hd ,days ,no4 #ba1 ,august #ai1 #aijc2 ,moon's ,age #bf4hi ,days ---------------------------------------- -------------------------------- ,,index ---------------------------------------- -------------------------------- ,,index ,abenezra1 #bje4 ,abulfeda1 #bjj4 ,air on the moon1 #bcj4 ,albategnius1 #gh4 ,aliacensis1 #gh1 #bje4 ,almamon1 #bje4 ,alps1 #ig4 remarkable valley in1 #bbe4 ,altai ,mountains1 #gb1 #bjj4 chain of small craters near1 #bjj4 ,animal life on the moon1 #bbh4 ,apennines1 #aj1 #if1 #ajd1 #acg1 #adc1 #bbb1 #bcb4 ,apennines and ,caucasus1 strait between1 #bcd4 ,apianus1 #bje4 ,archimedes1 #adc1 #bcb4 ,aristarchus1 #aag1 #aec4 astonishing brilliance of1 #aab4 cause of brilliance of1 #aee4 possible composition of1 #aac4 ,aristoteles1 #gf1 #ach4 ,atlas1 #gj4 ,atmosphere1 lunar1 #ca4 disappearance of1 #bbh4 what has become of it1 #cb4 ,atmospheres1 how they may grow or decrease1 #bcj4 ,azophi1 #bje4 ,barry1 #ahi4 8,bay of ,rainbows10 #aji1 #aaa1 #adb1 #aeg1 #aeh4 ,bessel1 #bba4 ,bianchini1 #aaj4 ,birt1 #ahh4 ,blancanus1 #gh1 #aid4 ,bonpland1 #ahi4 ,bubbles on the moon1 #ahf4 ,bullialdus1 #ahj-ahb1 #ahc4 mountains near1 #ahc4 ,byrgius1 #adg4 ,calippus1 #bbc4 ,campanus1 #ahe4 ,capuanus1 #ahe1 #aif4 ,carpathian ,mountains1 #bae4 ,cassini1 #bbe4 ,catharina1 #gb1 #ach1 #aii1 #bjf4 remarkable valleys near1 #aii-bjj4 ,caucasus ,mountains1 #ig1 #bbc4 ,caucasus and ,apennines1 strait between1 #bcd4 8,cavern life0 on moon1 #bbi4 ,cichus1 #ahe1 #aif4 ,clavius1 #ii1 #aja1 #adf1 #aib4 length of great wall of1 #aic4 ,cleft near shore of ,mare ,nubium1 #ahf4 ,clefts on moon1 resemblance of1 to geological 8faults10 #ahg4 ,cleomedes1 #ef4 ,color on moon1 #aee4 ,colorado ,caon1 possible likeness of1 to cleft on moon1 #aah4 ,copernicus1 #ajb1 #baa4 an argument for the volcanic theory1 #bab4 buried ring near1 #bag-bah4 crater pits near1 #bac4 hexagonal form of1 #bab4 ,craters1 lunar1 formation of1 ascribed to falling masses1 #bja4 theory of1 advanced by ,w4 ,k4 ,gilbert1 #bjj4 ,cyrillus1 #gb1 #ach1 #aii1 #bjf1 #baj4 8,dark woman0 in moon1 #acc4 ,darwin1 ,prof4 ,george1 #f4 ,dawes1 #bbd4 ,day and night on moon1 #fc4 ,day on moon1 length of1 #ie4 ,earth1 light of1 on moon1 #ej4 shadow of1 effects of1 as shown by ,prof4 ,william ,h4 ,pickering1 #bh4 shadow of1 its size and length1 #ah4 ,eclipse1 lunar1 #ag-ah4 earth's atmosphere and1 #bg4 moon visible during1 #bf4 ,eclipses1 lunar1 colors visible during1 #bi4 fix historic dates1 #bi4 number of1 in year1 #db4 when annular1 #da4 ,eclipses1 why they do not occur every month1 #ch4 solar1 different from lunar1 #bg4 number of1 in year1 #db4 why of greater scientific value than lunar1 #bh4 ,endymion1 #gj1 #acb4 ,eratosthenes1 #ajd4 ,eudoxus1 #gf1 #ach4 ,fracastorius1 #gc4 ,fra ,mauro1 #ahi4 ,full ,moon in winter1 why it runs high1 #agj4 ,furnerius1 #fc4 ,gases1 escape of1 from moon1 #bbi4 from planets1 #cc4 molecular velocity of1 #cc1 #bbi4 ,gassendi1 #aag4 ,gauricus1 #aif4 ,gay ,lussac1 #baf4 ,gemma ,frisius1 #bjb4 8,geology0 of moon1 #fg4 8,giantism0 on the moon1 #aic4 ,gilbert1 ,w4 ,k41 theory of lunar craters advanced by1 #bjj4 ,gravitation on moon1 #cd-cf4 ,grimaldi1 #aba1 #acb4 ,hmus ,mountains1 #ib1 #bbj4 ,hansen1 theory of1 in regard to the other side of moon1 #aci4 ,harbinger ,mountains1 #aah4 8,harvest ,moon10 #aga4 ,heat of moon compared with that of sun1 #afd4 ,helen of ,troy1 #ib4 ,hell1 #aif4 ,hercules1 #gj4 ,herodotus1 #aab1 #aeh4 cleft near1 #aah4 ,herschel1 ,sir ,william1 his supposed discovery of active lunar volcano1 #aab4 ,hipparchus1 #gh4 ,hoar frost on moon1 #cd4 8,hunter's ,moon10 #aga4 ,inhabitants of moon1 #ca-cb1 #hh1 #ie4 would not be visible with most powerful telescope1 #abj4 why they might be giants1 #aic4 ,kepler1 #aad1 #ada1 #aeb4 ,kies1 #ahe4 ,lacus ,somniorum1 #ic1 #bai4 ,landsberg1 #bag4 ,langrenus1 #ef1 #abc1 #acb4 ,lava floods on moon1 #gc1 #aeb4 ,libration1 effects of1 on visibility of parts of moon1 #eg-eh1 ,note4 ,life on the moon1 #bcj4 ,light of moon compared with that of sun1 #afc4 ,lindenau1 #bjb4 ,linn1 changes in1 #bcc4 observations of1 by ,professor ,pickering1 #bcc4 observations of1 by ,schmidt1 #bcc4 ,loewy and ,puiseux1 opinion of1 on lunar 8seas10 #bbj4 ,longomontanus1 #aja1 #adf1 #aej1 #aie4 ,lubiniesky1 #ahd4 ,lunar charts1 their relative accuracy1 #afa4 ,lunar history1 #fb4 ,lunar month1 #ab4 ,lunar nomenclature1 #ei1 #adg4 number of objects bearing names1 #afa4 singularity of1 #bjc4 ,lunar plains1 darkening of1 near sunset1 #add4 ,lunar sickle1 rule to determine position of1 #afh4 ,lunar vegetation1 #cb4 ,maginus1 #ajj1 #adf1 #aif4 ,manilius1 #abb1 #bbb4 ,marco ,polo1 #bbb4 ,mare ,crisium1 #eb1 #ee4 ,mare ,fcunditatis1 #fe4 ,mare ,frigoris1 #gf4 ,mare ,humorum1 #ajf1 #aag1 #aej4 ,mare ,imbrium1 #ajc1 #adb1 #add1 #bbd4 irregularities in the floor of1 #bcb4 islands in1 #bca4 ,mare ,nectaris1 #fh1 #ace4 ,mare ,nubium1 #ajb1 #adh1 #ahj4 ,mare ,serenitatis1 #gd1 #ace1 #bai1 #bcb4 bordering cliffs of1 #bbj4 ridges in the floor of1 #bcd4 ,mare ,tranquillitatis1 #gd1 #ace4 ,mare ,vaporum1 #ajc4 8,marsh of a ,dream10 #fh1 #ia4 ,mass of moon1 #ce4 ,maurolycus1 #ge1 #adb1 #bjd4 ,menelaus1 #ib1 #bba4 ,mercator1 #ahe4 ,month1 lunar1 #ab4 ,moon1 birth of1 and ,pacific ,ocean1 #f4 distance of1 from earth1 #h4 greatest distance of1 from earth1 #h4 influence of1 on growth of vegetation1 #afc4 least distance of1 from earth1 #h4 life on1 #bcj4 other side of1 #aci4 seen by daylight1 #adi4 separation of1 from the earth1 #f4 turning of same face of1 toward earth1 #ai4 ,moon and earthquakes1 #afe4 ,moon and the weather1 #afd4 ,moon and volcanoes1 #afe4 8,moon ,maiden10 #aj1 #if1 #ajc1 #abb4 ,mount ,hadley1 #bbb4 ,new ,moon1 photograph of1 #di4 ,new ,moon and the weather1 #afi4 ,newton1 deepest crater on moon1 #ajg4 ,nicollet1 #ahh4 ,night1 advance of1 over moon1 #aca4 length of1 on moon1 #ie4 lunar1 coldness of1 #acf4 ,nodes of moon and their revolution1 #ch-ci4 ,oceanus ,procellarum1 #aje1 #aej4 submerged rays in1 #aea4 ,orbit of moon1 #h4 ,origin of moon1 #f4 ,pacific ,ocean and birth of moon1 #f4 ,palus ,somnii1 #fh4 ,path of moon about sun1 #af-ag1 ,note4 ,petavius1 #fb1 #abc4 ,phases of moon explained1 #ac-af4 ,phlgrean ,fields1 #fj4 ,photographs1 lunar1 #dg-di4 in series1 #eg4 peculiar tone of1 #ade4 why they are reversed1 #eb4 ,photometry1 lunar1 #aec-aed4 ,piccolomini1 #gb1 #bjj4 ,pickering1 ,prof4 ,william ,h41 observations of ,linn by1 #bcc4 on effects of earth's shadow on moon1 #bh4 opinion of1 regarding changes in ,plato1 #bbf4 theory of ,tycho's rays by1 #abf4 ,pico1 #bca4 ,pitatus1 #ahf1 #aie4 ,plato1 #aje1 #aad1 #acb1 #bbe4 changes observed in1 opinion of ,prof4 ,william ,h4 ,pickering regarding1 #bbf4 vegetation in1 #bbg4 ,plinius1 #bbd4 ,poetry of the moon1 #if4 ,posidonius1 #bbd4 ,prism binoculars for viewing moon1 #abb4 ,proclus1 #fh4 remarkable brilliance of1 #ij4 ,projectile force on moon1 #cg4 ,promontorium narium1 #ahi4 ,promontory ,acherusia1 #bbd4 ,promontory ,heraclides1 #aji4 ,promontory ,laplace1 #aji4 ,ptolemus1 #ih4 ,pytheas1 #baf4 ,rabbi ,levi1 #bjb4 ,reinhold1 #bag4 ,riccioli1 nomenclature of1 for lunar objects1 #fi4 ,rings1 ranges of1 on moon1 #ig-ih4 ,riphan ,mountains1 #aij4 ,rotation of moon 8braked0 by tides1 #bj4 ,rotation of moon1 illustrated1 #ai-bj4 ,sacrobosco1 #bjf4 ,schickard1 #aae4 ,schmidt1 observation of ,linn by1 #bcc4 ,schrter1 8lunar city0 discovered by1 #bah4 8,seas10 lunar1 character of beds of1 #adb4 ,shadow of moon during eclipse1 #dj4 length of1 #dj4 ,shadows on moon1 topography revealed by1 #ajj-aja4 used to measure heights on moon1 #fc4 ,sidereal revolution of moon1 #aa4 ,sinus stuum1 #ajc4 ,sinus ,iridum1 #aji4 ,sinus ,medii1 #ajc4 ,sinus ,roris1 #aei4 ,size of moon1 #h4 ,sky as seen from moon1 #bi4 ,snow1 can it exist on the moon8 #fi4 ,snow1 non-existence of1 on moon1 #fi4 ,south polar region of moon1 #gg4 ,south pole of moon1 #ajf4 ,stadius1 #bah4 ,stfler1 #ge4 row of rings near1 #bjd4 8,straight wall10 #ahg4 ,strait between ,apennines and ,caucasus1 #bcd4 ,sulpicius ,gallus1 #bbb4 ,sunrise1 slow progress of1 on moon1 #id4 ,sunshine1 effects of1 when vertical on moon1 #ajj4 ,surface of moon1 nature of1 #i4 size of1 #i4 ,synodic revolution of1 #aa-ab4 ,tacitus1 #bjj4 ,telescopic power1 limits of1 #abj4 ,teneriffe ,mountains1 #bca4 8,terminator10 meaning of1 #fc4 ,thetetus1 #bbe4 ,theophilus1 #ga1 #ach1 #aih1 #bjf4 crater pits near1 #baa4 grandeur of appearance of1 when highly magnified1 #bjg4 great mountain fold near1 #bjg-bjh4 what would be seen from wall of1 near sunset1 #bjh4 ,tidal attraction1 forcing moon away in reaction of1 #f4 8,tidal friction10 #bj4 ,tides1 causing of1 by moon and sun1 #ba4 effect of earth's rotation on1 #be4 service rendered by1 #bb4 simultaneous occurrence of1 on opposite sides of earth1 #bc4 when highest1 #ba4 when lowest1 #bb4 ,twilight1 why none on moon1 #fd4 ,tycho1 #aj1 #ih1 #ajf1 #adf1 #aia4 longest ray of1 #ic1 #bba4 ray system of1 #abd4 rays of1 #ii4 theory of ,nasmyth1 #abd-abe4 theory of ,pickering1 #abf4 ,vegetation on moon1 #cb1 #aae1 #adb1 #add1 #bbg4 ,vendelinus1 #ei1 #abc4 ,venus seen by daylight1 #adi4 ,verne1 ,jules1 8,trip to the ,moon10 #d4 ,volcanic craters on moon1 #fj4 ,volcanoes1 lunar1 #ed4 contrasted with those of earth1 #hd4 effects of gravitation on size of1 #hf4 ,water on the moon1 #ec4 8,weathering0 on the moon1 #aig4 ,weight on the moon1 #cf4 ,werner1 #gh1 #bje4 ,wilhelm ,i41 #ajb1 #aie4 ,zagut1 #bjb4 ---------------------------------------- -------------------------------- ,,books ,,by ,,garrett ,p4 ,,serviss4 ,other ,worlds4 ,their ,nature1 ,possibilities1 and ,habitability in the ,light of the ,latest ,discoveries4 ,illustrated4 #abmo4 ,cloth1 #a4bj net2 postage1 #aa cents additional4 ,this book presents the very latest conclusions in regard to the nature and the habitability of the other planets4 ,it is written in popular style1 and1 at the same time1 is scientifically accurate in its statements4 ,it is a convenient handbook of information concerning the solar system1 but by no means a dry1 scientific treatise on the subject4 ,it might be said to resemble ,proctor's celebrated 8,other ,worlds than ,ours0 brought up to date4 ,the last chapter1 on 8,how to ,find the ,planets10 is unique and should prove very useful4 ,pleasures of the ,telescope4 ,a ,descriptive ,guide for ,amateur ,astronomers and all ,lovers of the ,stars4 ,illustrated with charts of the heavens and with drawings of the planets and charts of the moon4 #hvo4 ,cloth1 #a4ej4 8,this is a book which will give intense pleasure to everyone who uses it and follows its clear instructions40--,louisville ,courier-,journal4 8,every person of culture should possess at least a passing acquaintance with the planets1 stars1 and constellations4 ,with a little patience and comparatively small effort ,mr4 ,serviss's new book will enable anyone to obtain this knowledge40--,los ,angeles ,herald4 ,astronomy with an ,opera-,glass4 ,a ,popular ,introduction to the ,study of the ,starry ,heavens with the ,simplest of ,optical ,instruments4 #hvo4 ,cloth1 #a4ej4 8,we are glad to welcome this popular introduction to the study of the heavens4444 ,there could hardly be a more pleasant road to astronomical knowledge than it affords4444 ,a child may understand the text1 which reads more like a collection of anecdotes than anything else1 but this does not mar its scientific value40--,nature4 ,d4 ,,appleton ,,and ,,company1 ,,new ,,york4 ---------------------------------------- -------------------------------- ,,books ,,on ,,astronomy4 ,popular ,astronomy4 ,a ,general ,description of the ,heavens4 ,by ,,camille ,,flammarion4 ,translated from the ,french by ,j4 ,ellard ,gore1 ,f4,r4,a4,s4 ,new ,revised ,edition4 ,with #c ,plates and #bhh ,illustrations4 #hvo4 ,cloth1 #d4ej4 ,the author is the most popular scientific writer in ,france1 and the present work was considered of such merit that the ,montyon ,prize of the ,french ,academy was awarded to it4 ,the subject is treated in a very popular style1 and the work is at the same time interesting and reliable4 ,the work has been newly revised throughout and an appendix added1 showing all the important advances made in astronomy up to the year #aijg4 ,the ,earth's ,beginning4 ,by ,sir ,,robert ,,stawell ,,ball1 ,,ll4,d41 ,f4,r4,s41 author of 8,the ,story of the ,sun10 8,an ,atlas of ,astronomy10 8,star-,land10 etc42 ,lowndean ,professor of ,astronomy and ,geometry in the ,university of ,cambridge2 ,director of the ,university ,observatory1 etc4 ,with four colored ,plates and numerous ,illustrations4 #abmo4 ,cloth1 #a4hj net2 postage1 #ah cents additional4 ,this book will make admirable reading for persons of any age4 ,it provides a clear and popular explanation of the great problem of the earth's beginning4 ,it is believed that no exposition of the nebular theory and its infinitely wide ramifications has been made that is at once so simple1 so original1 and so comprehensive4 ,dr4 ,ball's success as a lecturer in this country indicates his gift of popular exposition1 and this book will rank as one of the most attractive presentations of scientific fact and theory for general readers4 ,the ,sun4 ,by ,c4 ,a4 ,,young1 ,ph4,d41 ,,ll4,d41 ,professor of ,astronomy in ,princeton ,university4 ,new and revised edition1 with numerous ,illustrations4 #abmo4 ,cloth1 #b4jj4 ,the ,expanse of ,heaven4 ,by ,,richard ,a4 ,,proctor4 ,a ,series of ,essays on the ,wonders of the ,firmament4 #abmo4 ,cloth1 #b4jj4 ,other ,worlds ,than ,ours4 ,by ,,richard ,a4 ,,proctor4 ,the ,plurality of ,worlds1 ,studied under the ,light of ,recent ,scientific ,researches4 ,with ,illustrations1 some colored4 #abmo4 ,cloth1 #a4be4 ,light ,science for ,leisure ,hours4 ,by ,,richard ,a4 ,,proctor4 ,a ,series of ,familiar ,essays on ,scientific ,subjects1 ,natural ,phenomena1 etc4 #abmo4 ,cloth1 #a4ge4 ,the ,story of the ,stars4 ,by ,g4 ,f4 ,,chambers1 ,f4,r4,a4,s41 author of 8,handbook of ,descriptive and ,practical ,astronomy10 etc4 ,with #bd ,illustrations4 7,library of ,useful ,stories47 #afmo4 ,cloth1 #ce cents net2 postage1 #d cents additional4 ,d4 ,,appleton ,,and ,,company1 ,,new ,,york4 ---------------------------------------- -------------------------------- ,transcriber's ,notes3 ,missing or obscured punctuation was silently corrected4 ,typographical errors were silently corrected4 ,inconsistent spelling and hyphenation were made consistent only when a predominant form was found in this book4 ,text that3 was in italics is enclosed by underscores 7italics72 was in bold by is enclosed by 8equal0 signs 7bold7 had extra character spacing by 8plus0 signs 7stretched74 ,the use of a caret 77 before a letter1 or letters1 shows that the following letter or letters was intended to be a superscript1 as in ,st ,bartholomew or #ajth ,century4