OUR PUBLIC SCHOOLS COLUMN

Otago Daily Times, Issue 16544, 18 November 1915, Page 2

OUR PUBLIC SCHOOLS COLUMN

FOR SENIORS AND. JUNIORS. (Conducted by Magisteii, to whom all communications must bo addressed.) [Magißtcr will be glaa to receive Nature Notee, marked popere coutaiiiiuj; educational articles, diugrame, detuiln at experiments, etc., ot scholastio interest to teudiexs and pupils. Correspondents must use only osis side of the paper, and whether using a pen name or not, mutsl send both HA.UU Mid AI)JL>UISSS.j SPHAGNUM MOSS. The other day there appeared in the Times a paragraph on sphagnum moss and a friend Jias lent mo the -Shetland Times, containing half a column article on its value lor dressing wounds of soldiers arid sailors, and how to gather it and make it lit for use. 'I hero is any amount of it in the vicinity of Dunedin, and it is used largely m potting plants and in packing plants to travel any distance. There aro two kinds, sometimes found close together. This, of course, is referring to the Shetland Islands, though perhaps tile same conditions obtain here. One ie of a brighter green colour, and has more pointed leaves; this is known as Sphagnum cuspidatum (L., cuspis, a spear). The other is of a darker green, end sometimes -displays beautiful! shades of red and yellow. Its leaves aro blunter, and have a fanciful resemblance to a boat, hence the name Sphagnum cymbifolium (Kymbe, a boat). This is the better kind. Both kinds havo button-like crowns of loaves, which sometimes mass together as Sphagnum cushions. The following briefly outlines the method of drying:—This, in the Shetland Islands, is done by hand, using an improvised wringer made of two sticks about 2ft long, and a towel about 4ft long, and a piece of canvas similarly shaped. Spread the towel on tho -ground, a.nd lay moss upon it higher in tho middle, and tapering away until within about 6in of the ends, and allowing the two sides to fold over. " When this has been done, tho ends of tho towel free of moss are gathered together and tho sticks laid across them where tho moss ceases. Tho gathercd-up ends are then brought over the sticks and tucked under one of the foldedover sides. Two persons then face oneanother, and each grasps one end of tho stick with his right hand and the foldedover end of the towel with the left. Each person then 'twists the bundle by carrying his right hand upwards and to" the loft, changing the grasp of .the hands as required. After one or two turns the gathered ends of the towel are caught in the twist, i and both hands imiy be used to graso the ends of the stick and continue the wringing. This method is used by country people in wringing blankets." Alter this dressing , , it is suspended in bags, and the drying finished off by natural or artificial heat, and when picked over is sent to the war dressings' supply rooms." The gentleman who lent me this paper— by-the-bye. it has a label on it, "Opened, by Censor, 812 " —wants to know whether we could not send some of this moss to our men? I am sending a marked copy to tho Hon. James 'Alien, so perhaps he will institute inquiries. But why c-ensor n Shetland Times? I fancy that when the war is over it will be seen_ that, large as the number of men is serving King and country, from the Orkneys, Shetlands, Hebrides," etc., the Scottish Islands have been playing a very important part in tho naval strategy of th'e war.

CORRESPONDENCE AND NOTES.. In Munsey's Magazine, there has been appearing a series of articles on European countries, and as each article is ■ accompanied by illustrations and coloured maps, it is an attractive one, and the whole make an interesting swies. For that reason I want the set, but have overlooked some. I have "Italy" (the most recent). "Egypt," "Turkey," "Scandinavia," "Germany," "■llussia," and "Austria-Iliingary." There are two or three others, I think, and if anyone talcing Munsay's as fugitive literature, I shall bo glad of the other articles to make my set complete. One of my ideas is to give a brief synopsis of each, with perhaps a map. Has Poland appeared? Greece? Belgium? France? Holland? or Denmark? One or two have, but not all. Road,Mr Morris's notes to-day with more than the uetial care. Try to grasp the size .■ind_ distance of Canopus and tnen what an insignificant sun we have shining upon us,- and how microscopically small this world of ours is, though it ie being rent asunder with strife. ■ . Can any St. Bathans resident supplement the information contained in this note? Is the bird referred to a pukeko?:— St. Bathans, November 5. Dear Sir.,—On Thursday, November 4, at 5 o'clock in the morn ing, there appeared a strange bird which was thought to be a pukeko in the garden of Mr John Ashmoro at St. Bathane. It was first seen at the front door. It stayed in .the garden all day, but chiefly around the door. The bird was very quiet when near the house, but when a few yards -away it was wild. It disappeared as mysteriously as, it came. . Colour: The back and were black; under the tail was white-; the breast and neck were bhie.; the legs were long, and rod in colour; tho bill was red and shaped like a turkey's; the crown of the head -was red, and there wcto red rings round the eyes. It is the first that has been seen in St. Bathans as far as I know.—Yours truly, : . IXQUIEEHf NIGHT SKY IN NOVEMBER. . J. F. Moiißis, Tautapere. Meridian Altitude.

Note.—The . above star-culminations (or meridian passages), also the altitudes, are calculated for a position riot fur. trom the JJuiiedm Triangle. . : ... Altair (Alpha of the Eagle) passes, the meridian in the afternoon 01 November 15 at. about 4.21, as stated above. ■ Hie halttime above tho Dunedin horizon vyorks out at 5.23.52, consequently ho ought to be visible from sunset to about 9.46 at Dunedin when he sets away to the westward nearly—west 12deg north (W. by N.). I have already pointed out that when Fomalhaut is passing tho meridian, Rigel'is above the eastern horizon. About 12 minutes after Rigil rises Fomalhaut passes the .meridian, and 37 minutes after iomalhaut pasees the meridian Aldcbaxan (Taurus) rises. When Fomalhaut is passing the meridian, Antares has disappeared in the west, and is about 18deg below the western. horizon; consequently we say that the sun is entering Scorpio, and when we look up our notes we find that,' allowing for a few corrections, our sun and the bright star Antaies come to the meridian together on the SOtii November this year. In ancient times, when the stars were the only calendars, the priests of Tanith, who ruled *ith a rod of iron in Carthage, always associated tho Mediterranean and neighbourhood with storms, etc., when tho " Seiser and Stinger" (Scorpion) had passed tho meridian at midnight in those latitudes. However, I must ' not get on to my hobby (astrology), but keep to the mathematical facts of astronomy. Our descriptive star this month is CANorus.—ln my notes on the southern night sky for June of the present, year I gave a deductive description of a giganticsun, Arcturus. This description was worked out by tho rules of chances of probabilities, and I stated, I think, that the description was by no manner of means to be considered as uuthorativo, but to bo considered, as my own conjectures in reference, to Arcturus, based on the principles of research and deductive reasoning. The same remarks apply with equal force to the circumpolar star Canopus. which is, of course, always above the horizon in the latitude of Dunedin and, next to Sirius, the brightest star in the sky. From its photometric magnitude wo learn a few interesting facts. Placed at the distance indicated by tho parallax of Arcturus, it would give off six times as much light as A returns; at the distance indicated by the parallax of Sirius it would bo 630 times brighter than Sirius; at the distance of Proxima (our ; nearest neighbour) Canopus would be trn thousand times brighter than Proxima, and would probably give forth nearly as much light at the distance of Proxima, vnst though it may be, as the full moon gives forth fit its average distance from th" earth. Fancy perpetual moonlieht over Duncrlin. Brought down to one radius of the tfrrcstri.il orbit, that is to say, brought down to tho sun's mean distance from the earth, Cnnopue would give off as mucli light as 21.900 of oi:r suns, and tho distnnpn from the oarth. to the sun would be nil too smnll to contain his vast splmrioiil volume. Under the circumstances mcntionM ■'hove, tho whole solar system would molt li!<" so manv soda crystals placed on a red hot stovp. Lot us now consirW the onormous distance of Canopus Your roadors will recollect that •«" estimate distance hv the star's nsirnllnx. It is rconera.Uy cnnnodorl that Dr El kin is as reliable an nuthoritv on nnrallax as nny nsfronomor who lias nnrtorbikmi this most difficult and clelicn.t.« observation. Accopting, then, Dγ N E!kin's estimate of tho parallax of Canopus, I finH that tho lia-ht journoy is 296 years, or 74 timos further away than Proxima four nearest star neighbour), or 18,750.000 times tho msan distance

r to the sun. In short, Caiiopus is not only the socoucl brightest star in the heavens, but it is also tho second in vastness of distance among the Mipor magnitude stars—that is to say, anion;.; still's above zero magnitude; in short, it is only exceeded by Kigel in distance. What is more, it' (Janopus were placed at the distance indicated by Higel, it would still be tho second , brightest star in the heavens, although it > would then bo rather more than 45 times ' the distance of ttirius. 'J ho above facts arc ! matters of ordinary calculation. What now I follows is speculative matter, more or less, and is here inserted to show the methods usually followed in order to arrive at other facts in connection with stars which > are not binary, or have no attendant satelj lite, at least, so far as astronomy knows at present. Caiiopus is one of these stare. ! Now, the great brilliancy of Caiiopus, com'i bined with its vast distance, sets us speculating as to its true size as compared with ' the Sun. In thin speculation we could bo I materially assisted ;£ we knew something ' as to its spectrum, that is- to say, if wo ' knew something which was generally known ' to bo accepted by those astronomers who ! investigate astronomical spectrum, and whose dictum would be accepted ae un- ! questionable by writers on astronomy. For 1 my own part, I suppose I have as good a 1 collection of books on astronomy as most ■ amateurs, but in only two of my books is ' there any mention of the Canopus spectrum, and in each instance the authority for the ' statement ie omitted. However, one state--1 ment is rather more definite than its pre- ■ decessor. Tho first statement I came across was, " Its spectrum (Canopus) is probably 1 of tho F type." In another book, of a rc- ' cent date, it is stated, " Canopus belongs. to the Procyon type of spectrum." Now, a star, whose typo of spectrum places the star in class F is known to be "intermediate" in the matter, etc., of which it is composed. Certain lines and colours prominent in type A (Sirius) are disappearing, but the metallic lines of typo G (Solar) arc not very pronounced. Consequently a star like the above is said to be "intermediate." between typo A and type G, and is allotted a type to itself, in this case, type ■F. Most books on astronomy give type F tho following sign, I-11, that is between 1 and 2. Intermediate is the same thing. Only I think the classification by letters is much simpler. Now, it so happens that We have several binaries or double revolving stars belonging to this intermediate or i ,, type. Whenever we have a binary wo can calculate its mass, not only as a combination, but singly—that is to say, the mass of each of the components. Again, when we are told that Canopus belongs to the Procyon type of spectrum we know that it is more than suspected that Canopus belongs to a type of etar in tho neighbourhood of F 5 G, or intermediate between the binary, say,. Gamma Virginis and our sun. In. that case Canopus (per unit of mass) would have the same density and surface luminosity as Procyon. The volume would increase as the density decreased, and if the volume increased so would proportionately the spherical area. In shoit, Procyon (as a typo of _ F 5 G) is known to be " three times brighter than tho sun in proportion to its mass." Without going quite the length of saying that Canopus belong* to. F 5 G we can safely follow an intermediary' course, and say that Canopus is probably a star'-be-tween type F and Procyon. Working out the problem on the above lines we come to the conclusion that Canopus is probably 104 times the diameter of the sun: that the density is about 0.73 of the sun; and that Canopus gives off twice as much light per unit of area as the sun. This last, I may explain, is what is generally ■ snoken of. in our books as the surface luminosity. The probable diameter of Arcturt's is, as-1 stated last June, rather more than 70 diameters of the sun, so you see that CanopuS is much bigger than Arcturus. Before dosing these notes we will just examine Canopus from another point of view. Suppose it were possible to condense him down to the solar or G typo of spectrum. Caiiopus would then consist of a treacly mass , like the sun, Arcturus, (a) Centuri, etc., all of which belong to the G solar, or metallic type of spectrum. If that were to happen _ to Canopus (and.it will in the course of time) let us speculate what would be tho result. He would first of all lose his. factor of luminosity, which I value at twice the sun per unit of mass. Next, as condensation increased, density would increase, and volume decrease proportionately. As volume decreased so would superficial area; and as the latter decreased so would the l ; ght-giying_ area. By the time density, 1.4, which is usually accepted as the solar density, is _ reached the volume, and hence tho light-giving area, would be reduced one half, and as the factor of luminosity was about 2. the diameter of Canoous would bo about 37 times that 1 of the sun, or about one-half_ the diameter of Arcturus. Under those circumstances he would still be a menace to _ the people of our planet, for although his sun power, as far as light is concerned, would be very much curtailed, yet his heat would be,, for certain, 1370 ' times the heat of tho sun, at the sun*s mean distance.

passage. Stare. h.,m. s degrees. Altair .4 20 40 35 ! 27 25 Fomalhaut, 7 .26 59 74 10 25 (a) Cnicis 8 57 52 1R .31 41 Achci-n-ir 10 08 35 78 13 54 (b) Centauri 10 33 46 15' 51 49 Proxima ■ .„ 11 09 47 i6 23 03