"Some of the streaks from Kepler radiate in the direction of Aristarchus, others towards Copernicus, cutting right through the rays from those formations. From this it is gathered that Copernicus was formed first, then Aristarchus, and Kepler still later on in the moon's history.

"The surrounding wall of Kepler is comparatively low with respect to the lunar surface level, but the depth of the crater is nearly ten thousand feet below the mountain peaks. The whole formation is covered with the same light-reflecting material as the streaks which surround it."



CHAPTER VI

THE SCENERY OF THE MOON'S SOUTHERN HEMISPHERE

I now directed M'Allister to steer across the lunar equator into the southern hemisphere, and our attention was soon attracted by a very large walled plain on the eastward side of our course.

John asked me what it was called, and I explained that it was named Grimaldi, being also well known to observers as the darkest tinted of all the large lunar formations. As seen from the earth it appears a narrow ellipse, but we could see its full width, which is 129 miles, the length being 148 miles. It is also noteworthy as one of the few plains which are convex in section, and it is so large that its area is equal to the combined area of the whole of the counties of England south of the line of the Thames, including Cornwall.

I showed M'Allister this formation on our map, where it appears only a narrow ellipse in consequence of the moon's curvature, and pointed out how very different was its appearance now we could see over its whole extent. Other formations nearer to the moon's limb appear still more foreshortened when viewed from the earth.

John here remarked that "these large ring-plains covered immense areas, and, now that we could actually see them, their magnitude was more impressive than anything we could have imagined from merely hearing or reading about them."

"Yes, John," I said, "from our altitude of more than ten miles above the lunar surface we command a much more extensive view and gain a better knowledge of details than we could obtain even if we landed on the moon. For instance, if we could stand down in the centre of one of those very large rings, we should imagine we were in the midst of a boundless open plain. The mountains all around us would be so distant that, owing to the sharp curvature of the lunar sphere, they would all be below the horizon, notwithstanding the fact that many of them are several thousands of feet in height. So, for all we could see of them, those mountains might be non-existent.

"In the case of somewhat smaller rings we might perhaps see, here and there above the horizon, just the topmost peaks of some of the more lofty mountains."

M'Allister was now struck with an idea, and exclaimed, "Professor, I notice that many of these great walled plains are very flat, and I should think they would make fine golf-links, for there would be plenty of room to send the ball flying!"

"Undoubtedly," I answered, "you would have plenty of space for that; and I can tell you that you would be able to send the ball flying six times as far as you could on the earth with the same expenditure of force, because the moon's gravitation is only one-sixth of that of the earth."

"That would be grand," said M'Allister. "I should like to have a few turns at golf on the moon."

"Ah, but you would also have extra long tramps after your ball," I told him, "so you would get plenty of exercise; but, for the reason already mentioned, you would be able to get over the ground six times as easily."

"Well, Professor, I should not mind the distance in those circumstances," he answered jauntily.

"Perhaps you like jumping exercise too," I said. "Only fancy, M'Allister, if you wanted to jump across one of those narrower cracks! Why, if you could jump a distance of ten feet on the earth, you could jump sixty feet on the moon just as easily! Some of our athletes have jumped a length of twenty-six feet, so the same persons could with equal ease jump 156 feet on the moon! What do you think of that for a long jump?"

"Heh, Professor," he replied, looking rather bewildered, "what a jump! Why, I should think the mon was never coming down again!"

"I say, though, M'Allister, after all I am inclined to think you would not find golf on the moon altogether a pleasant game," said John.

"Why not, mon?" inquired M'Allister.

"Well," answered John, "I was thinking that if you sent your ball flying into one of those cracks which are several miles deep you would find yourself eternally 'bunkered,' for no niblick ever made would get you out of that."

M'Allister laughed so heartily at this idea of John's that we both joined in his mirth; then I recommended him to wait until we reached Mars if he wished to enjoy a game of golf, for there he would be sure to find enormous stretches of level ground.



[Illustration: Plate IV

INDEX MAP TO CHART OF THE MOON

1. Bay of Rainbows

2. Plato

3. Sea of Cold

4. Alps Mountains

5. Great Alpine Valley

6. Cassini

7. Autolycus

8. Aristillus

9. Archimedes

10. Timocharis

11. Lambert

12. Euler

13. Sea of Showers

14. Aristarchus

15. Herodotus

16. Ocean of Storms

17. Copernicus

18. Apennine Mountains

19. Sea of Serenity

20. Haemus Mountains

21. Sea of Conflicts

22. Proclus

23. Sea of Tranquillity

24. Sea of Fertility

25. Hevel

26. Kepler

27. Grimaldi

28. Flamsteed

29. Bonpland

30. Gassendi

31. Sea of Vapours

32. Hipparchus

33. Albategnius

34. Ptolemaeus

35. Alphonsus

36. Arzachel

37. Theophilus

38. Cyrillus

39. Catherina

40. Sea of Nectar

41. Langrenus

42. Vendelinus

43. Petavius

44. Schickard

45. Wargentin

46. Tycho

47. Maurolycus

48. Clavius

49. Newton

50. Straight Wall

51. Sea of Moisture

52. Sea of Clouds]

Proceeding on our tour of inspection, we crossed the Ocean of Storms to a point near the central part of the lunar surface, and I showed them the fine walled plain called Ptolemaeus. This is 115 miles in diameter, and contains an area as large as the combined areas of Yorkshire, Lancashire, and Westmorland, its highest peak being 9000 feet in altitude. It forms the most northerly of a line of walled plains, the most southerly being Arzachel, which is sixty-six miles in diameter, and has a very depressed floor; while one peak on the walls rises to a height of 13,000 feet.

Passing farther west, we next examined another splendid group of three ring-mountains, arranged in a line running nearly north and south, viz. Theophilus, Cyrillus, and Catherina. The first is the most northerly, and is about sixty-four miles in diameter, with several very high peaks—one rising as much as 18,000 feet, and two on the opposite side being 16,000 and 14,000 feet high respectively. Even the central mountain is very large in area, and 6000 feet high. "That," I remarked to M'Allister, "is nearly half as high again as Ben Nevis, the highest mountain in Scotland, which is, after all, only 4400 feet high."

"Ben Nevis, Professor, is 4406 feet high!" corrected M'Allister.

"That's right, M'Allister," said John, clapping him on the back, "stick up for bonnie Scotland, and don't let her be robbed of that six feet of mountain!"

Proceeding, I then said that Cyrillus, the middle ring, was, as they could see, very irregular in shape; and the walls were in some parts very much broken and damaged.

Catherina is the largest of the three, being over seventy miles in diameter, and its highest peak is 16,500 feet in altitude.

I should have liked to have shown them the splendid double-walled plain called Petavius, which has a convex floor some 800 feet higher in the centre than at the edges. We were, however, too late both for that and Langrenus, another fine formation on the same meridian, for the sun had set upon them and they were in darkness, so it was no use going any farther in that direction.

We now directed our course over the Sea of Clouds till we arrived at what is known as the "Straight Wall."

"M'Allister," I said, "that ought to interest you, for there is a somewhat similar formation in Scotland. You see this is an escarpment, or cliff, over sixty miles long, and varying from about 600 feet to 900 feet in height.

"This cliff is one of the best known examples on the moon of what in geology is termed a 'fault,' indicating either that one part of the general surface has been greatly elevated, or that the adjoining part has been depressed. We have many examples of such 'faults' on the earth—for instance, one runs a long way across Scotland, from Stonehaven round to Helensburgh, between the Highlands and the Lowlands, and is about 120 miles in length. That is about twice the length of the Straight Wall; so you see that Scotland can beat the moon in that respect!"

This brought M'Allister up to the scratch. "Scotland," he exclaimed excitedly, "can hold her own in most things! Why, mon, the empire is indebted to her for the finest statesmen, the cleverest lawyers, the best engineers and scientists, and, allow me to say, the bravest soldiers in the whole world! Scotsmen go everywhere, and can do anything!"

"Oh yes, M'Allister," said John, with a laugh, "and a Scotsman has got to the moon! but, please, do not forget that two Englishmen planned the trip, and devised the means of accomplishing the journey!"

M'Allister smiled a rather wintry smile, and then subsided. John was a bit too smart for him that time.

Passing on, we inspected the large cleft running parallel to the Straight Wall, and the small mountain close by named after Birt, the well-known selenographer. We then crossed the Sea of Clouds again, and had a long look at the great system of straight clefts near Campanus and Hippalus, together with the fine walled plain Gassendi, the floor of which is at some parts 2000 feet above the lunar surface. I had often studied this through the telescope, as it is a most interesting formation.

"Well, Professor," remarked M'Allister, "I have travelled nearly all over our own world, but in all my journeyings I have never seen such wild and rugged scenery as I have during the few hours we have been passing over the moon. The mountains seem to be split and rent in all directions, especially where there are volcanic craters in the neighbourhood—and, really, they seem to be everywhere; while landslips are very numerous, and the mountain passes are extremely rugged and gloomy."

"Yes," I replied, "my telescopic observations had prepared me for a great deal, but the weird ruggedness of the lunar scenery exceeds all my anticipations."

"What is the explanation of it all?" M'Allister inquired.

"I should think, M'Allister, that much of it was originally caused by the extreme violence of volcanic outbursts," I answered; "but the excessive expansion and contraction, resulting from the alternate spells of intense heat and intense cold to which the moon is continually exposed, will account for the formation of many of those tremendous chasms and precipices which we see everywhere around us, as well as for the huge mounds of dislodged rocks and debris, which are piled up in such chaotic confusion on the ledges of the mountains and round their bases.

"On the earth such debris would very soon have become smoothed by atmospheric erosion, the interstices would have been filled up with dust and soil, while the growth of vegetation would have added a new charm to the effect.

"You have seen the great landslip in the Isle of Wight! When it fell all was wild desolation, but it has become covered with such a luxuriant growth of vegetation that it now presents a scene of beauty.

"On the moon, however, there is neither atmosphere, rain, nor moisture to produce weathering of the rocks or to encourage the growth of vegetation; so the rocks remain just as sharp, rugged, and bare as they were ages ago when they were first split off from the mountains.

"No doubt very large masses of rocks are still frequently being dislodged, and if we could see them falling from the upper part of a mountain, rebounding along the spurs, with fragments flying in all directions and ultimately dashing to pieces at the base, it would seem to us most uncanny not to hear the slightest sound arising from all this apparent commotion. Without an atmosphere, however, no sound could be produced, no matter how many thousands of tons of rock might fall to the ground.

"Tremendous changes of this nature may be happening on the moon, but our telescopes are not powerful enough to enable us to see the results. They would have to cover an area of miles to be noticeable, unless they presented some particularly striking configuration."

"Professor," exclaimed M'Allister, "how is it that all the shadows on the moon are such a dense black and so sharply defined at the edges?"

"That," I exclaimed, "is entirely owing to the absence of the atmosphere. On the earth, even at night time, some light is diffused by our atmosphere, and shadows are never dense black even when thrown by a bright sun. On the moon it is black darkness everywhere outside the direct rays of the sun, and there is no gradual diminution of the darkness about the edges of shadows such as we see on the earth. The only mitigation of the blackness is seen where some light is reflected across from the rocky walls on which the sun is shining.

"In those deep recesses down at the bases of the mountains the cold must be most intense and the darkness truly awful. It all looks very nice when the sun is shining, but appearances are often deceptive, and do not improve on a closer acquaintance."

We could not have landed upon the moon if we had desired to do so, for no provision had been made for a supply of air by means of helmets and other apparatus. I kept my own counsel in this matter, as I had very good reasons for discountenancing any proposal to investigate the lunar scenery too closely.

By a curious coincidence, not long after this conversation we had ocular demonstration of the fact that the moon is liable to changes from other agencies than those of expansion and contraction.

We were looking at some distant mountains which were in the full sunshine. Suddenly a dark shadowy looking mass shot across the sky and struck one of the mountain peaks some distance down from the top. The peak seemed to be immediately demolished, and vanished from our sight!

M'Allister gazed spellbound; but John excitedly exclaimed: "Did you see that, Professor? One moment the peak was there, and the next moment it was gone!"

"Yes," I said. "Undoubtedly that dark shadow was a large meteoric stone. Many have fallen on our earth at various times, some being tons in weight. Usually, however, they are so small that on entering our atmosphere they become fused by the friction and changed to dust. Larger ones are partially fused, and often split into fragments in the upper air. The moon, having no atmosphere, is quite unprotected in this respect; and meteorites moving at enormous speeds, probably over forty miles in a second, travel unchecked and unaltered in character until they strike the lunar surface. It is estimated that immense numbers constantly enter our atmosphere and are destroyed; but the moon must be continually exposed to bombardment by meteorites of considerable size.

"Many of our ships have been lost at sea in calm weather, and their fate has remained a profound mystery; but it is not at all improbable that some of them have been destroyed by large meteorites, for several instances are recorded of ships having very narrow escapes from these dangerous missiles from outer space."

Passing on towards the south-west, we had a long look at the magnificent formation named Tycho. It is a ring-plain nearly fifty-six miles in diameter, the mountain walls having some peaks over 17,000 feet in height. I drew their attention to the long bright ray-streaks which radiate in all directions for many hundreds of miles from the neighbourhood of this formation, to which I alluded when we had been looking at the rays from Proclus. Tycho and these bright streaks can be seen from the earth when the moon is full without the aid of a telescope, if one possesses good eyesight.

An enormous number of ring-plains and ring-mountains exists all over the southern half of the moon's disc; in many cases there are rings within rings, and others where they have overlapped or cut into previously formed rings.

Moving almost due south, we passed the large but partially ruined walled plain known as Maginus. This ring has a floor which is no less than 14,000 feet below the lunar surface. We then arrived at that favourite object for telescopic observers which is named Clavius. This is an enormous ring-plain, being over 142 miles in diameter, and encloses an area of 16,000 square miles, thus being half the area of Scotland. It has a very depressed floor, and some of the mountains are 16,000 to 17,000 feet in altitude.

Farther on, and close to the south pole, we saw the very deepest of the lunar walled plains, which is named after Newton, who possessed probably the deepest intellect of any of our astronomers. A smaller formation south of Plato was originally named after him, but was not considered worthy of a man of his scientific eminence, so the name was transferred to the formation we were looking upon. It is about 143 miles long and very irregular in shape, and its depth is about 24,000 feet—so deep, in fact, that the sun's light never reaches to the bottom; thus, when we look at it from the earth, the floor is always in shadow.

The Leibnitz Mountains, unfortunately, were not visible, as the sun had set upon them. I, however, mentioned that this range comprises several peaks which are believed to be the highest on the lunar surface, reaching as they do an altitude of 30,000 feet, and, according to some measurements, 40,000 feet. They are very difficult to measure, owing to the fact that they are really situated on the farther side of the moon, extending east and west of the south pole, and are only occasionally brought into view by the moon's libration; even then they are seen in profile, and so situated that they cannot be measured with certainty. They are, however, so high that they blunt the southern cusp of the moon when it is in crescent form.

I now directed M'Allister to turn the vessel in a north-easterly direction, and we moved across to the last objects which I proposed to examine. One was the large walled plain "Schickard"—about 135 miles in diameter—which encloses several other rings; the other, which lies to the south-east of it and close to the moon's south-eastern limb, is probably the most unique object on the lunar surface. As we gazed upon it I explained that the formation, which is known as "Wargentin," would probably in the usual course of events have been a ring-plain about fifty-four miles in diameter, but it really is a high plateau of that size, with very low ramparts. It is evidently a ring-plain which became filled to the brim with lava, or mud, that welled up from the interior of the moon; and the mountain walls, being exceptionally strong and without any breaks or gaps, withstood the enormous pressure of the lava, which therefore solidified and formed the great plateau as we now see it. The low ramparts, which we noticed here and there, are really the isolated peaks and ridges of the mountains forming the walls. This is the only known instance of such a formation; but probably others would exist had not the walls of the rings given way under the pressure of the lava. The walls of several ring-plains have been quite carried away, and, in some cases so obliterated, that it is now difficult to make out the original shape of the rings.

Having taken a last look at this unique object, I directed M'Allister to set the machinery in motion and rise for the purpose of quitting the moon.

"But," interposed John, "are you not going to have a look at the back of the moon, Professor?"

"No, John," I answered, "only a small portion of it is now in the sunlight, the rest is in the blackest darkness, so we should not be likely to learn much more about it than we know at present."

"Do you think the moon is inhabited?" he then asked.

"No, I do not think it is; no sign of life has ever been discovered, and we have seen nothing to indicate its existence here. The prevailing conditions seem to preclude the possibility. Think, John, if there is any life, what must it be! Without any atmosphere—therefore, not a sound to be heard, for all would ever be in the most deathly silence—no breath of wind; never a cloud nor a drop of refreshing rain, nor even dew; intense heat in the sunlight and the most intense cold everywhere in the shade! If any life does exist, it is most probably down in those gloomy, dark and cold recesses at the bottom of the ring-mountains, where there may possibly be some remains of an atmosphere. It would, however, be life in such a dreadful and debased form that I would rather not think about it at all.

"For a somewhat similar reason, I have directed M'Allister to keep the Areonal at least ten miles above the lunar surface all the time we have been passing over it. When we saw it from a distance it was, as you know, an object of surpassing beauty; and as we have seen it from here it has still been pleasant to look upon. This is truly a case where distance lends enchantment to the view; for, if we went down close to the surface, we should find it a scene of the weirdest and wildest desolation—more horrible than anything seen during a nightmare, and more terrible than anything imagined by the insane!

"No, John," I concluded, "let us retain our memory of the moon as a thing of beauty, and leave it at that."

"I quite agree with your view of the matter, Professor," John replied; so I gave the signal to M'Allister, who was awaiting the result of our discussion, and we soon left the moon far below us.



CHAPTER VII

WE RESUME OUR VOYAGE—THE SUN AND THE SKY AS SEEN FROM SPACE

All the time the Areonal had been near the moon some of our machines were storing up fresh power, and we had accumulated a supply amply sufficient to meet any extra requirements in the event of our arrival upon Mars being unduly delayed.

We now turned and looked back at the earth; and, as the moon was so near to it at that time, the earth's disc appeared very nearly two degrees in diameter, or nearly four times the usual apparent diameter of the full moon as seen from the earth. The crescent of light on its right-hand side was rather wider than when we last looked at it; but so many clouds hung over it, that we could not see what countries were comprised in the lighted portion of its surface. Owing to the light of the stars behind the earth being diffused by the dense atmosphere—in the same way as it would be diffused by a large lens—there was a ring of brilliant light like a halo all round the earth's disc.

Having passed away from the moon, I now gave M'Allister the necessary directions in order to keep the Areonal on a course which would enable us to head off the planet Mars at, as near as I could reckon, the point it would reach in fifty days' time. The course having been set, M'Allister was free to join us again, as the machinery required very little attention.

When he did so, M'Allister at once asked me a question. "Professor, can you tell me when it's going to be daylight? The sun has been shining for hours and hours, yet it's still night; the sky is blacker than the blackest night I ever saw, and the stars are all out!"

John laughed heartily, and said, "M'Allister, this is daylight! and all the daylight you will get until we reach Mars."

M'Allister turned to me with a perplexed look on his face and asked, "Is that right, Professor, or is he trying to pull my leg, as he said he would?"

"Oh yes! It's quite right, M'Allister," I replied. "It is now full daylight, and we shall have no more night until we reach Mars. That, as you know, will be seven weeks from the present time."

"Well, Professor," he exclaimed, "then how is it the sky is so densely black and the stars all shining so brightly? I never saw the stars in the daytime before, yet these are shining brighter than they do on the earth at night."

"Simply," I said, "because upon the earth we were surrounded by a dense atmosphere, which so diffused the sun's light that the whole sky appeared bright. The stars were there all the time, but their light was so overpowered by the brilliancy of the atmosphere that they were quite invisible to us.

"Now, we are out in space where there is no atmosphere at all, so the sky appears a very dense black; and the stars, having nothing to obscure their light, shine out more brilliantly than they do on the earth. They appear as bright points of light, and even the sun does not shed a general light over the sky, there being no atmosphere to diffuse it."

"Yes," he persisted, "but you said we should have no more night until we got to Mars!"

"Certainly," I answered. "Surely, M'Allister, you must have forgotten that night is brought about by the earth's rotation on its axis, and that the part which is turned away from the sun is in darkness because its light is hidden by the solid body of the earth, while the earth's shadow darkens all the sky. When, by the earth's rotation, that part is again turned to the sun then it becomes daylight. Remember we are not now on the earth, but out in space!"

"Of course I did know all that, Professor," he exclaimed, "but, just for the time, I had forgotten."

"Never mind, M'Allister, we all forget such matters sometimes, and this is quite a new experience for you. But just take a good look at the sun—have you noticed any difference in its appearance?"

"Yes, Professor, it doesn't look the same colour as when we saw it from the earth; it seems to have a violet tinge, like some of the electric lights in our streets. There are also long streamers of light around it, and coloured fringes close to the sun!"

"Yes, that is so," I said; "and we can see all those things now because there is no atmosphere. No doubt you have noticed that on the earth the sun appeared red when low down in the sky, and during a fog it appeared redder and duskier still."

"Oh yes, I've often noticed that," he answered.

"That was caused by our atmosphere which, when thick, absorbs all but the red rays of light. On a clear day the sun appears an extremely pale yellow, or very nearly white; still the atmosphere absorbs some of the light rays, so we cannot see its true colour as we do now. Those coloured fringes round the edges can only be seen from the earth by the aid of a special instrument, and then they do not show all their true colours.

"That pearly light all round the sun, and the long streamers that give it the appearance of an enormous star with six long points, form what is termed the solar corona, and this can only be seen from our earth during the very few minutes when an eclipse of the sun is at its totality. It is to see the corona and other surroundings of the sun, in order to study them, that astronomers go such very long distances—often thousands of miles—when there is a total eclipse expected, and not merely to see the eclipse itself. They hope, in time, to learn much from such observations; but if it happens that the sky is over-clouded during the period of total eclipse, then all their expense, and the time spent in preparations and rehearsals of their procedure, are, unfortunately, entirely wasted.

"Now, M'Allister, if you will take my glass you will be able to look at the sun and examine it without any risk to your eyesight, for it is provided with a dark glass to shut out all the dangerous glare. You will then see what the fringes and inner and outer coronas really are like."

He took the glass and looked for a long time at the sun, and, judging from his exclamations of surprise and astonishment, he was extremely interested and delighted with what he saw. John was also examining it at the same time through his own glass.

Presently the latter turned to me saying, "Professor, I no longer wonder that astronomers are prepared to travel long distances, and to risk a great deal of discomfort, and even hardship, in order to view and study the sun's surroundings. Of course to them it is not merely a sight to be seen, but the only means by which they can acquire a knowledge of solar physics. Merely as a sight, however, it is most wonderful. At many places all round the edge of the sun's disc I can see what look like coloured flames—pink, pea-green, carmine, orange, or yellow, all in incessant movement—shooting out at times, or waving and shimmering in a manner that is indescribable. The changes in form and colour are as sudden, yet as definite, as the changes produced by turning a kaleidoscope; while the intermingling of the various colours frequently produces an effect which I can only compare to the iridescent colours on mother o' pearl. Then all around and beyond the coloured fringe there is the light of the pearly inner corona; beyond that are pearly and violet-tinged rays curling away in both directions from the poles, whilst outside all are the long, pearly, and violet-tinted streamers which assume the shape of a large many-pointed star; and even these do not seem at rest. Though astronomers cannot see all that we do now, there must be sufficient visible to them to afford opportunity for a most interesting study."

"That is indeed the case, John," I replied. "Those coloured flames, for instance, form a study in themselves, which some observers make their particular hobby. As seen from the earth, they all appear some tint of red; and, normally, according to measurements, they seem to extend a distance of some 20,000 miles above the sun. They shift their position very rapidly indeed; movements at the rate of 100 miles a second are quite moderate compared with some which have been noted, yet one can scarcely realise such rapidity of motion. Frequently, however, these flames are seen to rise in immense masses to tremendous heights above the sun's surface, evidently driven upwards by explosions of the most intense energy. In 1888, for instance, one was observed which, in the course of two hours, rose to a height of 350,000 miles before it broke up; that is, at the rate of 50 miles a second all the time; but, as the force would become less and less as the distance increased, at the earlier part of the time the movement must have been far more rapid. When the impetus derived from the explosive force is quite exhausted, the top part of the mass of flame often spreads out like the top of a tree, then breaks up and falls back into the sun in large flakes of flame.

"It is supposed that these violent explosions are the cause of the spots we so often see on the sun when observing it with our telescopes; and, when looking at them in their earliest stage, we are probably looking at a mass of flame end on, instead of seeing it in profile, as is the case when the explosion occurs near the edge of the disc. The flames, as examined by the spectroscope, appear to be largely composed of hydrogen gas; and no doubt many other gases—some quite unknown to us—enter into their composition. They are termed flames, but are more probably immense volumes of incandescent gases. The corona itself is never seen twice alike; its shape and size vary at every eclipse, but the variation runs in a regular cycle from maximum to minimum.

"You will also observe that all around the corona, and extending a vast distance beyond it on both sides, is a fainter pearly light. This is what is termed the zodiacal light, and is believed to be the thinner portion of the sun's atmosphere. We can see it from the earth occasionally after the sun has set, extending far up into the sky in the form of a semi-ellipse, the base of which is over the place where the sun is."

M'Allister here asked me to tell him "What was supposed to be the actual size of our sun, and how far it was away from the earth?"

I answered that "The sun is about 865,000 miles in diameter; and that he would have some idea of what an immense body it is if he remembered that it would require 64,000,000 globes the size of the moon to make one globe the size of the sun! Yet, notwithstanding this immense size, our sun is quite a small body as compared with some of the fixed stars, which, as perhaps you may know, are really suns at an inconceivable distance from us. The bright star Sirius, which is visible during our winter time, is not only very much brighter in reality than our sun, but must be many times larger; and there are others known to be very much larger than Sirius. It has been computed that Arcturus is in mass 500,000 times as large as our sun!

"The sun revolves on its axis in a little over twenty-five days, but the exact period of its revolution is difficult to determine. The mean distance of the sun from the earth is about 92,800,000 miles. When we are farthest from it its distance is 94,600,000 miles, and when nearest, 91,000,000 miles—these differences, of course, arising from the eccentricity of the earth's orbit.

"The sun's density is only about one-fifth of the earth's density; so it is evidently mainly gaseous—at all events in the outer envelopes.

"The spots upon the sun often cover such an immense area, that if our earth were dropped into the cavity, it would be like placing a pea in a teacup! Some of the spots entirely close up in a short time, but others last for weeks."

We now turned from the sun and looked at the stars. Such a multitude were visible as we had never seen from the earth; for small stars, which there required a telescope to bring them into view, could now be plainly seen without any such aid, and their various colours were seen much more clearly. They all shone with a clear and steady light; the twinkling and scintillation of the stars, as seen from the earth, being caused by the vibrations and movements in our own atmosphere. We also saw many nebulae without using a glass.

The Milky Way was a most gorgeous spectacle, and its beauty utterly beyond description, as such an immense number of its component stars, and their different colours, were visible to the unaided eye; besides, we could trace wisps and branches of it to regions of the sky far beyond the limits within which it is seen from the earth.

We noted that the planets were also much more clearly seen; and the orange-red disc of Mars, of course, received our particular attention.

We had spent very many hours in viewing the moon, and a long time in examining the sun and stars; so we now sat down to a hearty meal, and, after a short time spent in conversation, we made our arrangements for taking turns in attending to the machinery, and then retired to bed.

[Illustration: DIAGRAM: showing the Positions and Movements of the Planets between the 3rd of August and the 24th of September, 1909: and the Course taken by the "Areonal" on the Voyage to Mars.

The dotted line joining the Earth to Mars shows the course taken.

The dotted Circles show the Orbits of the Planets. The thick arrows show the distances travelled by the respective planets during the period covered by the Voyage: the line at the back end of the Arrow being the planet's position on the 3rd August, and the points of the Arrows the position reached on the 24th September.

The Orbits of Mercury, Venus, the Earth and Mars are drawn approximately to scale, but those of the outer planets are not. On the same scale, the radii of the Orbits of the outer Planets would, approximately, be as stated below. These figures will afford some idea of the enormous distances separating those planets.

Jupiter 3 Inches Saturn 5-3/8 " Uranus 10-7/8 " Neptune 17 "

Drawn by M. Wicks

Plate V]



CHAPTER VIII

JOHN INSISTS ON GOING BACK AGAIN—A STRANGE, BUT AMUSING INCIDENT OCCURS

When we rose the next day the moon was a considerable distance away from us, but not so far off as might at first be imagined if one only considered the speed at which we were travelling; for, although moving at our full speed, the earth was following us up pretty closely, as the curve of its orbit would, for several days, run nearly in the same direction as we were going. Still, 2,000,000 miles a day was sufficient to make a diminution in the apparent sizes of the sun and Venus; and there was a gradual increase in the size of the planets, Mars and Saturn, towards which we were moving. As regards the fixed stars, however, there was no change in our surroundings, as they are such an immense distance away—the nearest being, at least, twenty billions of miles from the earth, that a few million miles more or less make no difference in their apparent size, or in their positions in regard to each other in the constellations as we know them in our maps.

As we were now fairly on our way, and moving rapidly in the direction we wished to travel, I thought it quite time to put into operation a scheme which John and I had previously decided upon, so I told M'Allister that he must be prepared to take a little change of air.

"Why, Professor," he exclaimed, "that sounds almost like a proposal for going to the seaside!"

"We certainly are not going there," I replied, "for we are rapidly moving away from all seaside resorts, and you are not likely to visit any of those places for a very long time to come."

"Well, mon, where are we going to get our change of air then?" he inquired; "you know there's no air at all outside of this vessel."

"Quite true," I answered; "so we must get our change of air inside the vessel."

"Yes," interposed John, "and, Kenneth M'Allister, you will have to make up your mind to have rather short commons of it; the same as we shall!"

"Whatever do you mean?" he inquired, now appearing really scared—for a dreadful thought had crossed his mind. "Mon, you surely do not mean that our machinery is giving out!"

"Oh no! not at all, M'Allister," I replied; "but perhaps I had better give you a full explanation of the matter:—

"You know we are bound for the planet Mars, where the air is very much thinner than that which we have been accustomed to breathe, and very probably it is composed of somewhat different constituents. In these circumstances you will understand that, if we landed upon Mars without having taken proper precautions, such thin air might make us very ill, even if it did not kill us.

"That little compartment next the store-room was arranged and fitted up for the special purpose of supplying a thin air in which we could prepare ourselves for the atmosphere of the red planet. So we are really going into training. The machines in that room will generate an attenuated atmosphere somewhat similar to our own, and this will be automatically mixed in a cylinder with a little oxygen and nitrous oxide gas, so as to make it as near as possible like what we expect to find upon Mars. When we commence it will be only slightly different from our own air; then gradually we shall reduce its density and change its quality until it is as thin as we shall require. Each of us must spend about eight hours a day in that little compartment, though it will not be necessary to take the eight hours continuously, for we may spend a few intervals in the other rooms.

"John and I will take general charge of the machinery in that room, and he will also look after your machines whilst you are with me in our Martian air-chamber. In addition to these arrangements, we have prepared a concentrated air of the same kind which we can carry about with us in bottles, so that by simply opening a little valve in the bottle we can inhale some of the air now and then when we are in the other rooms. By adopting this plan, I hope when we reach Mars we shall all have become so acclimatised that we shall be able to breathe the Martian air without much inconvenience."

"Heh, Professor," said M'Allister, "what a mon you are for planning things out; I would never have thought of that!"

"John had quite as much to do with the planning out as I had," I replied; "and as you now understand what we propose to do, we will at once commence our training, but we shall not feel much difference in the air for the next day or two."

We accordingly put our plan into operation, each of us making up at least eight hours' time every day in the Martian air-chamber, with the result that we gradually became accustomed to the thinner air, and could breathe it without any feeling of inconvenience.

As the days went on I began to notice that John was becoming very irritable; and so was I, though to a lesser extent. The closer confinement to one room was evidently beginning to tell upon us, and day by day the effects were more apparent on both of us, especially in the case of John; but, strangely enough, whilst we were becoming more depressed and irritable, M'Allister's spirits seemed to be rising every day!

It has often been remarked that if two or three people are shut up together for a considerable time, with no other companionship or change, sooner or later they are bound to fall out with each other.

Up to the present we had all agreed splendidly, but now John's irritability seemed to increase hourly; and as regards myself, I often found it necessary to exercise very great self-control to avoid giving very sharp and snappish answers to John's peevish and querulous remarks.

But the inevitable explosion came at last, and, like all explosions, was very sudden and unexpected when it did happen.

All the morning of the 2nd of September John had been wandering in and out of the various rooms, and frowning as though very displeased about something. I gave him a hint or two that he ought to put in more time with me in the air-chamber, but he took no notice of my suggestions. Presently, whilst I was in there alone, he came through, but, without speaking to me, went on into the store-room; and I heard him in there opening and shutting the lockers and cupboards, generally closing the doors with a loud bang, as persons do when in a very bad temper.

These bangs became more frequent and more violent, and at last succeeded each other with such rapidity that it seemed almost as though a vigorous cannonade were in progress.

I was wondering what could be the meaning of all this commotion, when suddenly the door opened, and John rushed into the room looking very cross indeed.

"I'm sorry, Professor," he cried, "though it's no use saying so; but we must go back to England again at once!"

"Good gracious, John!" I exclaimed, "what do you mean, and whatever has happened to upset you so and cause you to change your mind in this extraordinary way?"

"The deluge has happened," he replied, very crossly. "Professor, I've left all my stock of tobacco behind!"

"Never, John," I replied. "Why, you packed it up yourself; and I remember that when we overhauled the stores on our departure I saw the large tin of tobacco in your cupboard."

"I thought I packed it up," he answered, "but it's nowhere to be found now. As my tobacco supply had nearly run out I went to the cupboard this morning to get some more, and took down the big tin of twenty-six pounds labelled 'Tobacco.' I opened it, and what do you think it contained? You would never guess—well, it was tapioca!

"I've looked everywhere I can think of, without finding a trace of the weed."

Just then M'Allister came into the room, and, noticing John's vicious frown and my troubled look, asked what was wrong. We told him the news, but he only laughed, and, turning to John, exclaimed, "Heh, John, don't fash yourself about the tobacco, mon; we'll find you a substitute. There's more kinds than one."

"Substitute, indeed!" said John snappishly, "no substitutes for me!"

"Well, John," I interposed, "you can have as much of my tobacco as you like; it's a good brand, you know, and I shall not mind a shorter allowance, for it does not mean much to me."

"No," he exclaimed sharply, "I can't take yours, Professor; it's your own special brand!"

"Well, John," said M'Allister, "you're as welcome to mine as if it were your own, and it's fine strong stuff too. And you can have some of my Navy plug as well," he added with a grin; "you'll find it rare good chewing."

"I simply cannot take the Professor's tobacco," said John; then, angrily turning upon poor M'Allister, he cried, "And as for your filthy stuff, it's a downright insult to offer it to me!"

"John! John!" I implored, "do be reasonable; it's not at all like you to talk in this rude way, and you must know we really cannot go back now!"

"Reasonable!" he sneered. "Do you call it reasonable, Professor, to ask a man who is a lover of his pipe to go all the way to Mars and stay there for months without any tobacco!"

"Well, you will not accept mine, although you know perfectly well that you are heartily welcome to it. It's not your own particular brand, it is true, but it is a real good one. However, most likely you will find some on Mars; there's plenty of vegetation on that planet, without a doubt."

"Vegetation be hanged!" he angrily exclaimed. "What am I to do in the meantime? As for tobacco growing upon Mars—why, sir, I'd bet my bottom dollar that, outside our own world, there's no place in the whole universe where anything equal to my superb mixture can be produced. It's no use talking, Professor; as I said before, we must go back."

"We cannot go back," I replied sternly, for by this time I was becoming very irritated at his obstinacy. "The idea of going back so many million miles merely to fetch tobacco! Remember, we have travelled at least 57,000,000 miles on the way to our destination!"

John strode up and down, becoming more and more excited every minute, and was soon quite raging; yet it seemed most singular that the more John raged the more M'Allister laughed. I looked from one to the other in amazement and the most utter perplexity at this extraordinary change in their behaviour. Then all at once I saw a gleam of light, so to speak, and the solution of the mystery became clear to me.

The air we had so long been breathing when in the air-chamber, and when we made use of our air-bottles, was very similar to what is popularly known as "laughing-gas"; and undoubtedly we were all more or less experiencing the cumulative effects of the constant mild doses we had inhaled. Laughing-gas acts in a different manner upon persons of different temperaments: some will keep laughing, moderately or immoderately; others will become irritable, angry, or even pugnacious; whilst others again will weep copiously.

M'Allister was now talking rapidly and quietly to himself, laughing all the while, his eyes shining and twinkling merrily as though something intensely amusing were being enacted.

This seemed to react upon John, who apparently was irritated beyond control, and presently he roared out, "Kenneth M'Allister, stop that infernal grinning and chattering like a monkey! Stop it, I say! stop it directly!" But M'Allister took no notice and laughed louder than ever.

"Why, you confounded baboon," shouted John, "you're worse than any laughing hyena! Stop it, stop it at once, or I shall do you some mischief!" And he advanced towards M'Allister in such a menacing attitude that I had to rush between them to keep them apart.

He was now raging up and down the room, looking as angry as a hungry lion which has just had a long expected dinner suddenly snatched away from it; but the worse he became the louder M'Allister shrieked with laughter. The latter was now simply rolling about the room—for it could not be termed walking, it was so erratic—holding his sides and laughing, whilst the tears were chasing each other down his cheeks. He kept trying to speak, but had no sooner stuttered out the words, "Heh, mon! heh, mon!" than he was off again into another wild paroxysm of laughter, and was rapidly becoming exhausted.

Things were really becoming very serious indeed, and I saw that something must be done at once to put an end to this disturbance. So, going over to M'Allister, I took him gently by the shoulders and pushed him out of the room, saying quietly, "Go to your own room at once; but for goodness' sake don't touch the machinery until the air has had time to put you right again. Leave me to deal with John." He rolled off through the doorway, still laughing "fit to split" as people say.

Returning to John, I tried to calm him down; but it proved a long and difficult task, though at last I succeeded in persuading him to go with me into our living-room and sit down quietly.

After sitting there some time, puffing away at his pipe, the fresher air began to have its effect; and soon I judged that he was calm enough to talk the matter over and discuss the situation more reasonably.

Then I said: "John, my dear fellow, please listen to me. You know we have now travelled quite 57,000,000 miles on our journey, and that all our arrangements have been made with a view to reaching Mars not later than the 24th of September, because it will then be at the point where it is in opposition to the sun as seen from the earth. It is merely a sentimental reason so far as the opposition is concerned, but there are substantial reasons for not delaying our arrival.

"You say we must go back, but please consider all that such a course must involve. Though the earth has been following us up pretty closely on a slightly different course it is at the present about 13,000,000 miles away from us. You will see it out there on our left hand towards the rear of the Areonal; but we cannot go direct across to where it is now, for by the time we reached that point the earth would have gone ahead several million miles. Our only course is to head it off, and, taking the shortest line, that means a journey of over 12,000,000 miles. Therefore, we cannot reach England until the 8th of September at the earliest, and as we shall require at least a week to lay in fresh stores, it will be the 15th before we can start again.

"Starting on the 15th September we should have to travel at least 54,000,000 miles before we could catch up Mars, and as that will take twenty-eight days, we could not arrive there before the 13th of October. (See the chart.)

"Thus, we must sacrifice our chance of being upon Mars on the date of opposition, and also the opportunity of catching the first glimpse of our earth a few days later. If we continue our journey now and reach Mars on the 24th of September the earth will then be only 37,000,000 miles away; but by the 13th October it will be over 40,000,000 miles distant. There is the further objection that to get back again in reasonable time we must leave Mars by the 1st of December, and the loss of three weeks' time will deprive us of many opportunities of learning what there is to be found on the planet.

"Now, John, like a good fellow, just think over the matter quietly and reasonably; you will then realise that it is quite impossible to interrupt our journey and return to England as you suggest."

"I have thought it all out again and again," he replied, "and can only repeat, Professor, that it is quite impossible for me to go on minus my tobacco!"

"Was there ever such an obstinate and unreasonable man!" I thought to myself. "What can I do to put an end to this absurd difficulty?"



Resuming the conversation, and keeping as calm as I could in the circumstances, I placed the matter before him in all its aspects, and after we had been talking together for a long time, he seemed to be able to take a more reasonable view of the position. In order that something might be done to keep his mind from dwelling upon his proposal to return to England, I suggested that we should go to the store-room and thoroughly overhaul it.

He agreed to this, accompanying me to the store-room and pointing out the different places he had searched. The tins were in several sizes, but all were made square in order that not an inch of the available space might be wasted. We looked into a large number of tins which had not previously been examined, but without finding what we wanted.

At last a thought occurred to me, and I said: "You tell me, John, that you are quite certain you put up the tobacco and labelled the tin yourself, yet the tin so labelled was found to contain tapioca! Do you remember where the tapioca was stowed away?"

He pondered awhile, with his chin resting upon his fingers, then suddenly replied, "Yes, I think I know where it is," and, taking me over to another cupboard at the far end of the room, we made a further search and at last found the tapioca tin, opened it, and lo, there was the missing tobacco!

"Well, I'm blest!" said John, very slowly drawing out the words; then all his ill-humour suddenly vanished, and he burst into a most hearty laugh, in which I joined. Our laughter, indeed, was so mutually contagious, and so often renewed, that we had to sit down to finish it and recover ourselves.

Then John remarked, "Now, Professor, I think I can explain it all. You see I prepared and labelled those confounded tins before loading them up; so I suppose that when stowing away the parcels of tobacco I just glanced at the label on the tin and saw the letter T followed by the right number of other letters, and, taking it for granted that it was the tobacco tin, placed the tobacco in it. The only other tin left to pack was the one I supposed to be labelled 'Tapioca,' and no doubt, without troubling to look at the label at all, I put the tapioca into it; but, of course, it must really have been the tin labelled 'Tobacco.'"

Thus the matter was satisfactorily cleared up. John, having found his beloved weed and recovered from the effects of our patent Martian air, was now quite himself again, seeming very contrite, and apologising repeatedly for his rude conduct.

"That's enough, John," I said, as I laid my hand on his arm; "it is quite clear that what you did was mainly the result of the peculiar air you had been breathing, so I cannot blame you much. If I had not taken so many intervals in the purer air, I might perhaps have been equally affected; as it was, my temper was none of the sweetest."

M'Allister had also quite recovered by this time, and bore no ill-will towards John; indeed, I doubt whether he had any very clear recollection of what had occurred.

So that ended the matter; and this little explosion having cleared the air, we all settled down to our old amicable relationship. We, however, took the precaution of reducing the amount of nitrous-oxide gas in our mixture of air, with a view to preventing any similar untoward results in future.



CHAPTER IX

A NARROW ESCAPE FROM DESTRUCTION—I GIVE SOME PARTICULARS ABOUT MARS AND MARTIAN DISCOVERY

Things now went on quietly and, in fact, rather monotonously for several days; and then we met with another rather startling experience.

We were all sitting together in our living-room on the 9th of September, whiling away the time in a game of whist, and, as it was the final rubber and we were running very close together, we were quite absorbed in the play; although, of course, it was a dummy game.

Suddenly we heard a most tremendous crash, apparently from the right-hand side of the air-chamber, the vessel giving a violent lurch sideways, then shivering and trembling from end to end. The crash was immediately followed by a sharp rattling on the top and side of the Areonal, just as though a fusillade of good-sized bullets had been fired at us.

"My word! whatever's that?—one of the cylinders must have exploded," cried M'Allister, jumping up in alarm and running into the air-chamber. We followed him, and looked all round the room at the different machines and apparatus, but could find nothing wrong.

John, chancing to look up, however, at once noticed a large bulge on the inner shell of the vessel, high up on the right-hand side; and then, turning to me, pointed it out, saying, "I think, Professor, it is pretty clear now what has happened."

"Yes, that huge bulge explains itself," I replied; "undoubtedly a fair-sized meteoric stone has collided with our vessel. It is very fortunate that the stone was not much larger, or there would have been an end to the Areonal and to us as well. These meteorites travel at such tremendous speed that, on entering the earth's atmosphere, they become incandescent owing to the friction of the air, and, unless very large, are entirely consumed and dissipated into dust before they can reach the earth. Those that do fall are always partially fused on the outside by the tremendous heat generated by the friction of our atmosphere. These meteorites are what people call 'shooting stars,' and many are under the impression that they really are stars, until the difference is explained to them."

John said, "We ought to congratulate ourselves upon such a lucky escape from annihilation; for had our vessel been constructed of any metal less hard and tough than our 'martalium,' and without a double and packed shell, it must have been wrecked and entirely destroyed by the shock of the tremendous concussion it had sustained. Even the very metal of the casing might have been completely melted by the intense heat generated by the impact of the meteorite."

"Heh, mon!" exclaimed M'Allister; "it's all very well talking about our lucky escape, and putting it all down to your own cleverness in designing and constructing the Areonal; but you should rather give thanks to Providence for saving us, and for enabling you to take the precautions you did. I say, 'Thank God!'" he remarked, and he solemnly raised his right hand as he spoke.

"Quite right, M'Allister," replied John: "we are all too prone to credit ourselves with more than we are entitled to. At the same time, M'Allister, you must remember that we Englishmen recognise as fully as you do the over-ruling power of Providence, although we may not be quite so free in speaking about it in ordinary conversation."

"Yes," I added, "you may be quite sure, M'Allister, that we are equally as grateful as yourself for the mercy which has preserved us all from an awful death. My very first thought on realising our extremely narrow escape from destruction was to say 'Thank God!' but I did not say it aloud as you did. It is in matters like these that people differ according to their temperament and training; and it is not safe to judge another because, in any particular circumstances, he does not act in precisely the same way as we ourselves would."

Thus we travelled on and on, each day bringing us more than two million miles nearer to our destination. Mars was apparently increasing in diameter the nearer we drew to it, and the dark blue line around the south polar snow-cap, indicating the lake of water from the melting snow, was very conspicuous. The snow-cap had recently decreased rapidly, being now near its minimum and irregular in shape, for in the southern hemisphere it was now late in June. Pointing to the planet, I remarked, "There is our destination! We see it now as the poet pictured it for us, and the words of Dr. Oliver Wendell Holmes are very appropriate to the present circumstances:

'The snow that glittered on the disc of Mars Has melted, and the planet's fiery orb Rolls in the crimson summer of its year!'"

On the 18th of September we passed between the earth and Mars, nearly in a line with the sun. On that date Mars was in perigee, or at its nearest point to the earth during the present year. Its distance from the earth was then 36,100,000 miles, and it will not be so close again until the 24th of August 1924. We could not see the earth, as its dark side was turned towards us, and it was also lost in the brilliancy of the sun.

At this date we had travelled 88,000,000 miles since we left the earth, yet we knew it was there, level with our vessel, and only about 29,000,000 miles distant on our left hand, whilst Mars was only 7,000,000 miles from us on our right-hand side.

Our position now was as follows:—Taking an imaginary line drawn from the Areonal to Mars as the base line of an isosceles triangle, we were moving along the left side of the triangle, and Mars was moving in a slightly curved line along the right side. Our paths were therefore converging, and if all went well we should both meet at the apex of the triangle on the 24th September, as we had originally intended.

We therefore had six clear days to cover the distance of less than 12,000,000 miles, so we should have sufficient time to slacken speed at the end of the journey. (See the chart.)

Mars was rapidly growing in size and brightness, for the distance between the planet and the Areonal was quickly diminishing as our paths converged, and the various markings on its almost full round disc formed the subject of continual observation and conversation. We had noticed on several occasions a mistiness on some parts of the planet, which I attributed to the vapours raised from the canals by the heated atmosphere.

On the 21st of September, when we were all enjoying a smoke in the "evening," and conversation had dragged somewhat, John started us off on a fresh tack and gave us something to talk about for a very long time.

He winked at M'Allister and, looking at me with a knowing smile, said: "Professor, as we are nearing our destination it might perhaps be well if you now gave us some detailed information respecting the planet, similar to that which you gave us when we were approaching the moon. It would be both interesting and useful; for we should learn much more from an orderly statement of the facts than we should from several long but desultory conversations."

"Yes, Professor," chimed in M'Allister, "I'm quite ready to learn something definite about Mars, for I can't say I really know much about it at present."

"Very well then," I replied, "it is upon your own heads, and if you are willing to listen to a rather long story, I am prepared to do the talking. Please remember, however, that it will require some time to make matters clear and understandable."

"Fire away, mon," cried M'Allister, "we will listen as long as you care to talk."

So I began—"Mars, as no doubt you are aware, is a much smaller planet than the earth, its diameter being only 4220 miles, which is a little less than twice the diameter of our moon.

"It would require nine and a half globes the size of Mars to make one globe the size of the earth; and even then it would not be so heavy, because the average density of Mars is only about three-fourths of that of the earth. Mars is the next planet outside the earth's orbit, so is the fourth from the sun. The orbit in which Mars moves in its journey round the sun is very much more eccentric than the earth's orbit; in fact it is more eccentric than the orbits of any of the larger planets. As a consequence, the planet's distance from the sun varies greatly according to the particular part of the orbit in which it may be moving. Its mean distance from the sun is 141,500,000 miles, its greatest distance over 154,000,000, and at its nearest approach to the sun, or 'perihelion,' as it is called, its distance is only 129,500,000 miles. Mars travels in its orbit at a mean rate of 15 miles a second.

"As its orbit is also eccentrically placed in relation to the earth's orbit, it follows that its nearest distance from us in any particular years may vary greatly. The nearest possible approach it can make in regard to the earth is a little under 35,000,000 miles; when at the opposite point of its orbit its nearest approach is about 62,000,000 miles from the earth. As the years of Mars and the earth differ greatly in length, and the two planets move at different speeds, the very favourable oppositions can only occur about once every forty-five years; though a comparatively near opposition occurs about every fifteen years. Such a close approach we have just witnessed, and it will be fifteen years before Mars is again so near to the earth!

[Illustration: CHART: showing the Orbits of the Earth and Mars, and the relative positions of the two Planets, during the years 1909-10. Mars passed over the dotted portion of its Orbit in the year 1910.

The Outer Circle is the Orbit of Mars, and the inner Circle is the Orbit of the Earth. The Seasonal points on both Orbits show the Seasons in the Northern hemisphere. In the Southern hemisphere the Seasons are reversed, "Summer" occurring at the point marked "Winter," and "Spring" at the point marked "Autumn," &c. &c.

The dotted downward line on the left-hand side shows the course taken by the "Areonal", which left the Earth on the 3rd of August and arrived at Mars on the 24th of September. * Shows the point reached when John wished to turn back; and the lower dotted line, the alternative course then suggested.

The long dotted line running upwards to the Spring Equinox of the Earth shows the course taken on the homeward Voyage.

Drawn by M. Wicks.

Plate VII]

"The Martian year is equal to 687 of our days, but as the Martian days are slightly longer than ours, this really represents 668 Martian days.

"The entire surface of Mars contains an area of about 56,000,000 square miles, which is about one-fourth of the area of the earth's surface.

"Its gravity is only three-eighths of the earth's gravity, thus everything upon Mars would weigh proportionately lighter than on the earth, and the amount of labour required to do such work as digging or lifting would be lessened. There would, for the same reason, be greater ease of movement in walking, jumping, or running, and large bulky animals like our elephants could move with almost the same ease and freedom as our goats.

"Theoretically, we should expect to find the atmosphere upon Mars very much thinner than our atmosphere, and actual observation proves this to be the case. We are able to see details on the surface of Mars with very much greater distinctness than would be the case if its atmosphere were as dense as ours. Moreover, clouds are comparatively rarely seen; and the majority that are observed present more the appearance of clouds of sand than rain clouds. Usually, also, they float very much higher above the planet's surface than our clouds are above the earth's surface; ten miles high is quite an ordinary altitude, and some have been estimated as quite thirty miles above the planet.

"Many theorists have attempted to prove that, owing to the planet's distance from the sun, and the thinness of its atmosphere, the temperature of Mars must be very low, probably below freezing-point even at the equator. Dr. Alfred Russel Wallace has gone further than this, and suggests that the temperature must be eighty degrees Centigrade below freezing-point; that there is no water or water vapour on the planet; and that it is quite impossible for life to exist there!

"However, as the result of delicate bolometric experiments, careful calculations, and consideration of conditions affecting the result which have not previously received so much attention, Professor Very has arrived at a different opinion; and actual observation has shown that there is very little indication of frost outside the frigid zones. Even in the polar regions it is at times evidently warmer than at the earth's poles, because during the spring and summer the snow-caps upon Mars not only melt more rapidly, but melt to a much greater extent than our polar caps do. In 1894 the southern polar snow-cap of Mars was observed almost continuously during the melting period, and it was actually observed to dwindle and dwindle until it had entirely disappeared. It is rather strange to think that we know more about the snow-caps of that far-distant world than we do about those on our own earth.

"Owing to the lesser gravity on Mars the snow and ice which forms the caps would certainly be lighter and less closely compacted than the snow and ice upon our earth; but it is quite clear that it could not melt to any extent unless the temperature remained above freezing-point for a considerable length of time.

"It has, however, seriously been contended that the Martian polar caps are not snow at all, but frozen carbon dioxide—the poisonous dregs of what once was an atmosphere. Carbon dioxide, however, melts and becomes gaseous almost suddenly, but these polar snow-caps melt gradually, exactly as frozen snow would; so this theory fails altogether to fit the circumstances.

"Moreover, the water which accumulates all round the base of the melting snow-cap has been carefully observed on many occasions, and in the early stage of melting it appears blue in tint, but later on, as upper layers of snow dissolve and those nearer the soil are reached, the water presents a turbid and muddy appearance; exactly what might be expected when water has been contaminated by the surface soil.

"Dr. Alfred Russel Wallace declines to accept the blue tint as any proof that the liquid is water, and contends that shallow water would not appear that colour when viewed from a distance. You will, however, have observed that the water in all our shallow reservoirs appears intensely blue when observed from any distant and elevated point of view. It seems to me that when, as in the case of Mars, we have a very thin atmosphere laden with sand particles, we have exactly the conditions which would produce a very blue sky, and cause the water to appear a deep blue colour when viewed from a distance.

"It is also contended that water cannot be present on Mars, because none of our skilled spectroscopists has yet been able to demonstrate by the spectroscope that there is any water vapour in the Martian atmosphere.

"This, however, is generally acknowledged to be a very difficult and delicate operation; and, in any case, it is purely negative evidence, and cannot be accepted as final. I feel quite confident that sooner or later a means will be found of definitely proving the presence of water vapour upon Mars by the aid of the usual lines in the spectrum. There are too many evidences of its presence, such as clouds, hoarfrost, snow, and seasonal changes in vegetation, to warrant the rejection of the idea of its existence merely because it has not been detected by the particular means hitherto used by the spectroscopists.

"Mr. Slipher, of Flagstaff Observatory, has made many experiments with specially sensitised photographic plates. He has taken several photographs of the spectrum of the moon and others of the spectrum of the planet Mars. The plates of the lunar spectrum show a darkening of the 'a' band, which indicates the presence of water vapour, and we know that is due to the water vapour in our own atmosphere. The plates of the spectrum of Mars show a much more definite darkening of the 'a' band, and Professor Lowell contends that this can only be due to water vapour in the atmosphere of Mars.

"Professor Campbell has, however, made similar experiments, and is of opinion that Professor Lowell has been deceived by the water vapour in our own atmosphere. Thus the matter stands at the present time, and we must await the result of further investigation before we can consider the matter settled.

"I, however, regard it as a certainty that improved means will definitely show that water vapour undoubtedly exists in the Martian atmosphere, and it is not unlikely that other constituents of that atmosphere may also be identified, and possibly even the relative quantities may be ascertained."

John here remarked that he had read of it being contended that life could not exist on Mars because as water would boil at a temperature a hundred degrees lower than it did on the earth, it would be impossible to boil a potato properly, or make a good cup of tea. He thought, however, that if water boiled at such a low temperature, then the proportion of water vapour in the air would be increased, as evaporation would be more rapid than on the earth.

"Undoubtedly so," I replied. "The first argument, however, is very weak. For many thousands of years the people on the earth not only managed to live, but attained a high state of civilisation, yet we have no reason to believe that they ever ate potatoes or drank tea! Even in England we have only known and used these articles for about three hundred years! The inhabitants of any world would be suited to their environments.

"The polar-caps on Mars are shown on very early drawings of the planet; but, up to the year 1877, little was known of the general surface details beyond the fact that the general colour was orange-red, diversified by dark patches of blue-green in some parts, and some narrow, serpentine markings here and there. All these markings are now much more accurately drawn, as the result of more careful and continuous observation. Sir William Herschel suggested that the red colour was attributable to the vegetation of Mars being red, instead of green as on our earth; but it was generally considered that the red areas indicated land and the dark areas water. The work of our modern observers has, however, resulted in a general revision of our ideas on these points.

"It had long been reasoned that, as the earth was accompanied by a moon, and Jupiter had at least four, Mars, the intermediate planet, might be expected to possess a satellite. The planet itself being small, its moon would probably be very small, and likely to be overlooked when observing with the telescope, because its light would be overpowered by the light of the planet, which would make the telescopic field of view very bright. Up to the year 1877 the most powerful instruments had been used without success in the search for the supposed satellite.

"In that year Mars made an exceptionally near approach to the earth, and Professor Asaph Hall, of Washington Observatory, took up the search, using a splendid refracting telescope having an object-glass 26 inches in diameter. The methods he adopted were rewarded with success, for he discovered not only one, but two satellites of Mars, and they were given the names of Phobos and Deimos.

"Both these satellites are very close to the planet and extremely small, Phobos being less than 4000 miles from the planet's surface, and Deimos only 12,300 miles from it. As seen in the telescope, they are very faint points of light which cannot be measured by ordinary means, and the estimation of their size was a matter of great difficulty.

"Professor Langley gives an interesting account of the endeavour to estimate their size by the amount of light reflected, as compared with the light afforded by our own moon when full. It was a most difficult task, as the comparison had to be made by means of tiny holes drilled in metal plates; and for a long time it was impossible to find a workman who could drill a hole sufficiently small for the purpose, although one of those employed had succeeded in drilling a hole through a lady's thin cambric needle from end to end, thus converting it into a tiny steel tube. One would have thought such a feat impossible; yet what was now required was a hole smaller than the one thus made through the tiny needle."

"My word!" said M'Allister, "I would like to see the mon who did that piece of work, and shake hands with him; he must be a rare clever fellow!"

"Yes," said John, "and I would like to see the drill he used; for such a long and extremely slender tool, to be effective, must be as clever a piece of work as the steel tube."

"I may tell you," I proceeded, "that success was at last attained; and as a result of the comparison of our moon's light with that of Deimos, it was shown that if the general surface brightness of the latter were equal to that of our moon, then Deimos must be only 18 miles in diameter, or about a 15,000th part of the area of our moon's disc.

"To state the matter in another way—supposing our moon were only 18 miles in diameter, and was removed to the same distance as Deimos is from us, then it would appear only the very faint point of light that Deimos appears when viewed through the telescope.

"By the same means Phobos, the satellite nearest to Mars, was estimated to be about 22-1/2 miles in diameter. These dimensions, however, depend on the brightness of these satellites being exactly the same as the general brightness of our moon; and later experiments have fixed the sizes as 36 miles for Phobos, and 10 miles as the diameter of Deimos.

"I will not detain you much longer on this subject, as we shall be able to discuss it further when we arrive upon Mars; but I may now mention that, in one respect, the little satellite named Phobos is unique. It is the only satellite we know of which revolves round its primary planet in less time than it takes the planet itself to make one revolution on its axis.[6]

"Mars revolves on its axis in 24 hours, 37 minutes, and 22 seconds, thus the 'day' on Mars is nearly 38 minutes longer than our 'day.' Phobos revolves round the planet in the very short period of 7 hours, 39 minutes, and 14 seconds, and therefore makes more than three complete revolutions round the planet in the course of a single Martian day. The peculiar phenomena to which this very rapid motion gives rise, and the numerous eclipses which occur, will be matters of great interest to us all when we reach Mars. Our moon, as you know, takes a month to make one revolution round the earth."

"Professor," said John, "when we get to Mars, it will be rather a curious experience for us to see two moons shining in the sky at the same time!"

"My word!" exclaimed M'Allister, "two moons shining at once! If I go out and see such a sight as that, I shall think the whisky has been a wee bit too strong for me!"

"Well," replied John, "if your usual drink has the effect of making you see double, take good advice, and leave the whisky severely alone when you are on Mars, or else you will be seeing four moons all at once, and receive such a shock that you will never get over it!"

M'Allister laughed pleasantly as John said this. He is a real good fellow, and takes all John's chaff with the utmost good-humour; but, in justice to him, I must say that, although he sticks to his national drink like a true Scot, I have never once seen him any the worse for it. He knows his limitations, and always keeps within them.



CHAPTER X

THE DISCOVERY OF LINES UPON MARS—THE GREAT MARTIAN CONTROVERSY

After the little interlude with M'Allister, I resumed my remarks by saying that "The year 1877, so memorable for the near approach of Mars and the discovery of its two tiny satellites, was also the year in which a still more important discovery was made—a discovery, in fact, which has much enlarged our knowledge of the planet, and has also resulted in an entire revision of our conceptions respecting it.

"An Italian astronomer, Signor Schiaparelli, took advantage of the favourable position of Mars to observe it very carefully, and some time afterwards announced that he had seen upon its surface a number of very fine lines which had not previously been noticed, and these he had carefully charted upon his drawings and maps.

"This announcement started one of the most acrimonious discussions that the astronomical world has ever known; and although it is now over thirty years since it commenced, astronomers are still divided into two parties—one accepting the lines as demonstrated facts, the other either denying their existence, or endeavouring to explain them away by various more or less ingenious or fanciful theories.



"When Signor Schiaparelli's statements and drawings were first discussed, it was declared by some to be quite impossible that these fine lines could really have been seen by him: either his eyes must have been overstrained, or he claimed to see more than he actually did see. So warm did the discussion become that he soon withdrew from it altogether, but devoted himself to his work. As time went on, he not only verified his previous discoveries, but found numerous fresh lines, all of which appeared to run straight and true over many hundreds of miles on the planet.

"Milan then had a good clear atmosphere which was favourable for the observation of delicate planetary markings, and other observers who were well situated were able to see and draw many of the lines which Schiaparelli had discovered.

"It was, however, contended that such lines could not have any real existence, as it was asserted that they were too straight. It is quite true that straight lines on a rotating globe would appear curved when seen from some points of view, but if the objectors had carefully studied complete sets of drawings, they would have seen that the lines did assume a curved form in certain aspects of the planet.

"Then the very same people who denied the actuality of the lines because they were too straight, eagerly took up a suggestion that they were not actually narrow lines, but the edges of diffused shadings on the planet, apparently quite oblivious of the fact that the same objections must apply to them. Moreover, if there was difficulty in accepting the actuality of narrow lines, there must be immensely greater difficulty in believing that shadings could, in such a very large number of cases, all end in straight lines many hundreds or thousands of miles long, and always appear uniformly true, no matter upon what portion of the disc they might be seen, and whatever might be the angle of illumination.

"Besides, only a small proportion of the lines are connected with shadings. The shadings are more likely to be the result of the canals than the cause of the formation of illusory lines in so many cases.

"I have listened to many of these discussions, and have often been much amused at the tangle of inconsistencies in which some have involved themselves, by taking up fresh theories without regard to their previous contentions.

"As time went on each opposition of Mars brought the discovery of fresh lines, and numerous observers confirmed the reality of Schiaparelli's work.

"Professor Lowell, the well-known American astronomer, took up the study of Mars in a most thorough and systematic manner, and has since practically made it his life's work. An observatory was built at Flagstaff, Arizona, far away from towns and smoke, at an altitude of over 6000 feet above the sea-level, the site being specially selected on account of the clearness and purity of its atmosphere; while the observatory, being high up above the denser and more disturbed strata of air, afforded the most favourable situation possible for the proper observation of delicate planetary detail.

"There he continued the work which Schiaparelli had commenced, and, together with the colleagues with whom he has been associated, has, by long-continued and most systematic work, added greatly to our knowledge of Mars. Year after year has seen the addition of more lines on our maps of the planet, whilst many interesting discoveries have been made—one being that some of the fine lines were double, the second line always being equidistant from the first one throughout its whole length, no matter whether the lines were straight or curved.

"This caused a further outcry of objection. The observers were told that they had been overstraining their eyesight so that they 'saw double,' and also that they had been using telescopes not properly focussed. Such objections seem almost beyond argument, for no practical observer could use an improperly focussed instrument without at once discovering the defect.

"Besides, if the double lines were the result of eye-strain, or any other defect which might cause such illusions, all the lines would have been seen double, or at least all the lines running at the same angles; but as a matter of fact only a very small proportion of the lines were so seen, and it made no difference what position they occupied on the disc, or at what angles they were presented. Some of the doubles were, in fact, curved lines; and another point was that in some cases they were only doubled at certain seasons of the year.

"Other observers who saw the lines were charged with having studied the maps of Schiaparelli and Lowell until they had become obsessed with the lines, and when they looked through the telescope simply fancied they saw them!

"In England our atmospheric conditions are seldom really favourable to the proper seeing of the finer detail, and the very faint lines cannot be seen at all. The lines that are visible do not appear thin and sharp as they do to observers in more favoured climes, but rather as diffused smudgy lines, and so they are drawn by the observers. On a few occasions of exceptionally good seeing they have, however, been seen and drawn as finer and sharper lines.

"The visibility of the lines was, however, confirmed by so many observers of known integrity, and from so many different parts of the world, that the objectors were at last compelled to abandon the position they had occupied. Then a new theory was started, viz. that the lines were actually seen but did not actually exist, being really optical illusions arising from the apparent integration, or running together in linear form, of various small disconnected markings which were viewed from beyond the distance of clear seeing.

"The manner in which it was sought to prove the correctness of this theory appeared to me at the time (and still does so) as most weak and fallacious, and certain experiments I made only strengthened that opinion. However, scientific people accepted it as proof.

"In making this experiment schoolboys were seated in rows at different measured distances from a map of Mars, which they were told to copy. The map showed all the well-known dark patches and markings, but no fine lines. About the places where some of those lines should have been, dots, curls, wisps, &c., were inserted at irregular distances, and not always exactly where the lines should have been shown. The inevitable result was that the boys who were too far away to see clearly saw these small markings as continuous straight lines, and so drew them. In the circumstances they could not do otherwise; for if sufficient marks were inserted nearly in alignment, they would necessarily produce the effect of lines.

"These drawings were then acclaimed as proving that the lines seen on Mars were only discrete markings viewed from beyond the distance of clear seeing, and that the network of lines seen and drawn by so many skilled and careful observers of Mars had no actual existence upon the planet. Thus all their work was completely discredited.

"Experiments like these could not possibly prove any such thing, because it would be easy to insert in a map various markings which, when viewed from a distance, would appear to form almost any design that one might choose to depict. Any desired effect might thus be obtained; and I have seen many pictures so formed in which the illusion was perfect. When viewed from a distance each appeared to be a picture of something entirely different from what was seen when it was viewed from a near standpoint.

"The linear illusion could not arise from a mere multiplicity of faint scattered markings, but all the more conspicuous markings must be in alignment. It seems impossible to imagine that so many hundreds of lines on Mars could thus fortuitously be formed by illusion, and every line be connected to some definite point at each end.

"To argue that because illusory lines can be formed as in these experiments proves that the Martian lines are also illusions is claiming far too much. For instance, if I drew what was actually a map of South Africa, and was so seen at close quarters, yet in consequence of the insertion of numerous small marks and shadings formed a portrait of Lord Blank when viewed from a distance, it would be very far indeed from proving that every map of South Africa was a portrait of the noble lord, or that his portraits were all maps of South Africa.

"Moreover, as I myself saw, some of the boys were so unskilled that they had not even drawn correctly the outlines of the dark patches about which there was no dispute.

"It is obvious that such erroneous and unreliable work as this could not be regarded as evidence upon which truly scientific argument could be founded for the purpose of deciding such a contentious question; yet mainly upon this very slender and unreliable evidence meetings of two of our leading astronomical associations endorsed the illusion theory, and for a long time it held the field.

"M. Flammarion made some similar experiments in Paris, and even inserted spaced dots along the sites of canal lines on the map put up as a copy, yet not one boy drew a canal. M. Flammarion evidently was rather too sparing with his dots and marks.

"A long series of experiments was carefully carried out by Professor Lowell and his colleagues, from which it was deduced that if in any line on Mars there was a gap of sixteen miles in length, our present telescopes would suffice to discover it. It is most improbable that in so many hundreds of lines, several of which are over two thousand miles in length, there would not be numerous gaps over sixteen miles long if the lines were made up of separate markings.

"Yet it is found that every line is perfect in its continuity, and not only so, but uniform in width throughout its whole length, which would be impossible if the lines were made up of separate markings not in alignment.

"The illusion theory may, however, to a certain extent be correct, but this will prove exactly the opposite of what its supporters contend. It appears to have been quite overlooked that as there are so many thousands of miles of canals it is utterly impossible to suppose that the vegetation, which is all that we really see, is continuous and without breaks. It would indeed be most extraordinary if there were not very many long stretches of land which, for some natural or utilitarian reasons, were either bare of vegetation or so sparsely covered as to appear bare when viewed from the earth through a telescope. Some parts of the canals in hilly or rocky ground may pass through tunnels, and thus cause apparent gaps in the lines; or ground may be incapable of bearing vegetation, or purposely left fallow.

"It would, therefore, be no matter of surprise if more powerful instruments should, in moments of perfect seeing, reveal numerous apparent gaps in the lines. So far from proving they were not canals, such gaps are exactly what we should expect to find in connection with canals; and the lines would probably appear as irregular light and dark patches in alignment, because we do not see the canals themselves, but only the vegetation on the land which they traverse. Probably there are also many oases yet to be discovered along the canal lines.

"As I have already stated, it was asserted that the double lines were illusions arising from the causes already mentioned, with the probable addition of eye-strain and bad focussing. Assuming that the single lines are, as it is declared, illusions, we are confronted with the assumption that the doubles are illusions of illusions, and this is more than I can follow, it seems so improbable.

"Professor Lowell has devoted some sixteen years to close and continuous observation of Mars whenever it has been in a position to be observed, and many thousands of drawings have been made, the results being plotted down on a globe. In reply to the statements of occasional observers that the lines cannot be seen, he testifies that they are not difficult to see; and that any one who saw them in his exceptionally good atmosphere, and through his instruments, could have no doubt of their actuality. He rather caustically, but very justly, remarks in one of his books that his many years of personal experience in viewing these lines almost entitle him to an opinion on the subject equal to those who have had none at all!

"The proof of their existence, however, no longer rests only on the corroborative evidence of other observers, for, after years of experiment, Professor Lowell and his staff have succeeded in taking direct photographs of Mars, which show several of the disputed lines. One would have thought that would settle the question, but, although some of the more reasonable of the objectors have been convinced by the evidence of the photographs, many others still maintain their attitude of scepticism, especially those who have not themselves seen the photographs. They declare it to be quite impossible for any such photographs to be taken, because our atmosphere would prevent any photographic definition of fine detail on such small pictures; yet about ten thousand of these tiny photographs were taken during the near approach of Mars in 1907.

"As I possess a number of these photographs I can testify that they do show some of the lines, and persons who disbelieved have expressed surprise at their excellence. Success was only obtained by means of specially sensitised plates, for the ordinary photographic rays and ordinary plates were found useless, whilst the process of photographing so small and distant a planet is surrounded with difficulties.

"Even when attached to a telescope giving an equivalent focal length of nearly 150 feet, the camera only gives a very tiny image of the planet. The lighting of the small image is faint, but if additional power were used on the telescope to obtain a larger image, then its light must be still fainter, and thus a longer exposure would be required to obtain a picture on the plate. As Mars moves in its orbit and rotates on its axis, and our atmosphere is subject to continual movement and disturbance, any long exposure would result in a blurred picture, which would show no fine detail. So, as a short exposure is essential, only a small picture can be taken. Nothing is gained by any subsequent great enlargement of the picture, because the grain of the film of a quick plate is coarse; and, if enlarged, this also blurs out the detail.

"Having regard to all the difficulties which had to be surmounted, it was a great and undoubted triumph to secure detail on such tiny photographs of this distant world. As time goes on improvements will probably be effected and still better pictures secured; but enough has now been accomplished to prove that the lines cannot be illusions, but really exist upon the planet. If the eye can be deceived in this respect, the camera cannot.

"When Professor Lowell first took up the work of Martian observation only 113 lines had been discovered by Schiaparelli, but the number has gradually been added to from time to time, as the result of the work done at Flagstaff Observatory and elsewhere, and has now reached a total of considerably more than 600, the lines forming a fine network extending all over the planet.

"Mr. Slipher, who accompanied Professor Todd's expedition to Alianza in Chili, at the opposition of 1907, together with the observers at Flagstaff, discovered no less than 85 new canals, including some doubles, nearly all being in the more southern portions of the southern hemisphere.

"In addition to the discovery of so many fine lines, we also owe to the acumen of Professor Lowell a reasonable explanation of what they really are. Schiaparelli termed them 'canali,' an Italian term for 'channels,' but, popularly, this soon became corrupted into the term 'canals,' and this has turned out to be a much more appropriate word than such corruptions usually are.



CHAPTER XI

THE GREAT MARTIAN CONTROVERSY (continued)

"As the result of very long continued and systematic observation of the lines on Mars, together with carefully plotting them down on a globe, it was found that every line was continuous, uniform in width, and went straight from one definite point to another, not one breaking off in open space. Moreover, on being tested, nearly all were found to be arcs of great circles, and therefore the shortest possible lines which could connect any two points on a sphere. This fact strongly supports the idea that they are not natural but artificial formations. For a long time the lines were only seen on the red, or lighter, parts of the planet, but in 1892 an expedition was sent from Harvard Observatory to Arequipa, in Peru, for the purpose of observing the planet under very favourable conditions, and this resulted in important discoveries. Professor W.H. Pickering, who accompanied the expedition, was fortunate enough to observe that the canal lines extended over the dark or blue-green portions of the disc; and later observations have proved that this is the case all over the planet, and the lines are visible from pole to pole.