PATER'S CHATS WITH THE BOYS.

Otago Witness, Issue 2170, 26 September 1895, Page 47

PATER'S CHATS WITH THE BOYS.

The Moon ami the Eclipses. Within the past month wo have had two eclipses, or partial one?, and I dara aay it will be very many years before an eclipse of the gun and of the moon will be again seen in any one place with such a Bhorb interval batwesn. ' Do you know any thing about the birth of the moon ? I imagine that some years ago I gave Sir Robert Ball's explanation, but a ' brief outline of the theory won't be amiss, : even suppooing I did. ' Away in the dim past, perhaps eona of J years ago, our solar system was a huge ball of gaseous matter. Gradually it cooled, and ' in coolingf, and aa it revolved, portions were thrown off from the central muss,, and these portions became the planets revolving about the central mass— our eun and one of the stars of space. Then ao the planets revolved some of them threw off other portions, and theaa portions aro the moons or satellites. THE PLANKTS' MOONS. Mercury and Venus, the inferior planets — that is, the planets between the earth and the Bnn _have no mosns so far as I havo read. The earth has one, -which was eclipsed a week or two ago, and which in its transit across tbe sun's surface laßt week caused tbe eclipse of tho bud. Mars has a couple. Ours takes about four weeks to mako tho circle of the eartb, but one of Mara's moons takeß less than eight hours, and the other about 30. So on Mars is seen the spectacle of one moon catch : »g up to and passing the other three or four times before it sats. Tho smaller of these two moonß is only nine miles in diameter, and the other, which is only 11 miles through, is less than GOOO miles away from its primary or parent planet. Jupiter is still better off, for it has four moons, one of which is nearly 1,200,000 miles from its parent ; but Saturn is best off of the lot, for it has eight of them, one of which is over 2,300,000 miles from Saturn, and takes nearly 80 days to get round. I wonder how they calculate the months on those planets. Imagine a month of eight hours and another of all but 80 days I Uranus, again, isn't quite so well off, for ifc has to be content with four. And what about Neptune 1 It is supposed that one moon has been discovered, but I do not kuow anything about it. According to the latest edition of Chambers's Encycloricdia it hasn't even baen named. 1 oun moox. | But I must hark back. It is our moon we have to deal with; the others may come in some other day. lam going to give you a few figures. I Bhall not give you exact ones, but approximate ones, bo that you may easily remember Borne of them. Its diameter is about 2160 miles, or, say, a little more than one-fourth of the earth's ; but the surface is only about one-thirteenth. Then as to volume, or siz?, or bulk, but not weight, mind, the moon is about one-fiftieth of that of the earth. Kjw as to weight compared wiih the earth. Volume and rveigM or viass are quite distinct. A. trass of unpressed hay may be of the same

'" ■" ••'*<>">• «■ '"" '■HM«ii»» 11 iim I mass or weight as that of another trnsc which has been comprised by horse of steam, or some other powor and whioh therefore ocouplea less balk or space, co is of less voluma. So with the moon; for while 50 moonn rolled into one would equal the earth in bulk or volume, it would take 80 to equal it in mass or weight, ITS GRAVI'IY. Beiug so much B mailer than the eartb, gravity is less on the moon than with u». There a boy weighing with us, say 1001b would weigh about 151b. What a pity we— a privileged few with a monopoly— cannot buy by moon's weight and sell by earth's w»ightf, or better still by sun's woight; for if xrq could we would buy Bay 31b on the moon and sell it here as 20lb, or on the sun as a quartet of a ton I Good business that ! Even better than the new protective duties on boots. Again, a boy being so light on the moon, I imagine he would be able to jump, about 30ft high, or, say, over an ordinary church, and a good cricketer would throw a ball over a quarter of a mile — perhaps nearly half a mile. Then gravity being less, an objeot would fall vary gently compared with its falling speed here. A stone dropping 15ft a second on our earth would there fall only about 2£ffc. But with what terrific weight and speed an object would fall by compatison if trans-' ported from the moon to the tun. Three pounds falling on the moon about 2£ft in tho first second would become on the Bun a quarter of ton falling 500 ft in the first second. Au ordinary Echoolboy weighs about 9Clb, and In falling on the earth ho would acquire a velocity of 32ft at the end of the first second ; on the sun he would weigh fully a ton, and in falling would in the same time acquire the terrific rate of about 900 ft I But perhaps the moon has led me Into quite enough figures for the present. I have supposed a kind of Jumping Jack to be taking a little exerc'se on the earth, gun, and moon, so that you cau get a falut idea o£ the obanged conditions we should live under if transferred to one of tho other atoms of epaeo. As a matter of fact we could not exist on tho moon. There ia no air, no atmosphere, no molsturo ; and therefore no clouds, no animal or vegetable life aa we know it. Being destitute of air there is no blue sky, but pitchy blackness with brig lit beads in the s'lapa of tbe stars of space glistening-. There is no twilight, and the shadows are intensely deep. The planet is deadly still— it is, in fact, dead — and our earth i« gradually but eurely moving on to death too. Tbe moon is so much smaller, thtm the earth, that when it separated it— cooled dot?n much more quickly. Did it onca have human beings on it organised like ourselves 1 It ia bard to say. DAY AND NIGHT. When tbe moon dissolved partnership with the earth the day on both was about two and a-haif hours. That ha* lengthened with us to 24; but on the moon it has lengthened to between 600 and 700 hours— - In fact, a moon's day is the same aa our month. If I remember rightly, Mr Ball says that the length of a day on the earth la gradually increasing, and that it will increase until ib and the moon's days are equal.. Then I suppose our oarth will be as dead as the moon. I did intend writing upon other points that are interesting, but perhaps I have wiitten enough to arouse your curiosity. I may take up the subject again next week.

— New York : " What do you thiuk of cur park ? " Astute Traveller : "In one respects it's like that of ewry ether American city. Boetonijin : " How 1 " Traveller : " It's ths finest in the country." — One of the Proffa«ion. — A #ood story is told of a doctor who was oat late one night, when he was appioached by a footpad. "Gimme your money," said the marauder. The doctor turned round toward tbe tramp and in an offended tone exclaimed—" What are you doiDg over here 1 Go on the other side of the street : I'm working this side myself." Tho tramp begged pardoa for the breach of, etiquette and vanished.