OUR PUBLIC SCHOOLS COLUMN.

Otago Daily Times, Issue 13518, 15 February 1906, Page 3

OUR PUBLIC SCHOOLS COLUMN.

FOE BOYS AND GIRLS. [Conducted by Magistkb, to whom all communications must be addressed.] LIGHTNING. As I am wriiing (Tuesday evening) we arc having as (ine a display of lightning iu Dunodiu as I have ever seen here. On nnd above, the horizon lo the west ami tlio north-west thero is a heavy, solid black bank of clouds, while iho rest of the sky is clear, with a si ill atmosphere. Prom whore I stand two. flashes seem to originate near Saddle Ilill and to go along the horizon to the north in leaps, and at limes showing great brilliancy. [After I wrote this noto a heavy mist came up, through which tlio lightning still flashed - .] I think it was in this morning's paper (I am writing on Tuesday evening, remember) that mention was mado of a "washout" on tlio Otago Central line, tho result of a cloud-burst. It was, only .tlio other day that I chanccd upon an article in tho London Magazine on photographing lightning, and one i of tho remarkable photographs the writer took -showed not only tho lightning flash but also a descending cloud-burst. It was purely a chance snap, and is probably the only one ever taken. Now, as it is a favourito theory of mine that a groat deal can bo taught by seizing opportunities—more often than in set lessons,—l am giving you to-day a portion of the article. In some schools it can bo takon in connection with Naturestudy or science. _ The writer gives a simple experiment in electricity; here is another;—Doublo a piece of zinc, say tho size of a crown, and put it between tlio upper lip and _ tho gum; then put. a sixpence on tho tip of tlio tongue, Close tho .oyes, or go into a dark room, and on bringing the sixpence up inlo contact with tho zinc a decided flash of lightning will bo seen. Try tho experiment. Tho following is tho article as adapted .by omitting all details about photographing:— HOW I PHOTOGRAPH LIGHTNING. By James Leadbeateb. The majority of people seem to havo some inborn horror of lightning, which at the approach of a thunderstorm compels them. to seek _ efficient shelter,' and, by drawing the blinds, endeavour to shut out the. magnificent spectaclc the sky presents when tho artillery of Nature is iu full play. Generally speaking, too, people are 'strangely ignorant of the causes which produce lightning, and the forces displayed thereby; for, although there are soino to whom a thunderstorm has an irresistible fascination. and they arc eager enough to watch it from a coign of vantage, they seldom trouble lo consider tho scientific side of the combat of forces which thoy have just witnessed in the air. Consequently, until the camera came on the sccno, (he popular ideas nf lightning wore more or less incorrect, but they have been exploded by the success of photo'grapliy in securing permanent impressions of lightning-flashes. If we look at any old picture in which a thunderstorm is shown—and in a. great many modern ones, too, for tho matter of that—we invariably see lightning painted in zigzag form, which is precisely the shape it does not take. Photography teaches us I hat a flash is a long, trembling streak of light, throwing off branches in every case from a convex point, as though the flash were uncertain of the direction it intended to take, and so is reflected upon our eyes in quivering branches of light against tho blackness of the clouds. Tlio photography of lightning will bo found of remarkable interest to those who care for pictures of Naturo in her wildest form. But before beginning it is as well to know exactly what it is, and how it is brought ahoul. When, many years ago, Benjamin Franklin flew u kite which drew sparks from a thundercloud, it was proved for the.first lime that lightning and electricity wero the same thing. Electricity exists everywhere, and may be considered as being made up of two fluids, negative and positive. Hy various processes they become separated, and aro then latent; anil it is their reunion which is the sole cause' of thunder and lightning. By a little experiment at home yon can sec in miniature tho. whole mechanism of a thunderstorm. Having procured a pi ere of sealing-wax, suspend it in tlio air by a .thread ot silk, and it v.ill be found that another niece of rubbed sealing-wax, held in tlio hand, will repel the first. Or, if a pieco of glass is lmng iu tho same way, it will repel a second piece; hut the rubbed wax will attract glass, and Tubbed elass will attract wax. The reason of this is thai. Iho electricity produced on the nibbed glass is railed positive, and that, on the sealing wax negative; and it is whon these two como into contact that eruptions aro produced in the air, causing lightning. Now, whenever salt water is in contact with % earth, thero both fluids are Ovolvod in equal proportions and in hot weather especially there is a constant stream of invisible particles of water ascending into Ihe air, which, on condoiisulion, become clouds. These particles of water carry up with them smaller particles of olod I'icity, generally of tho positive kind, the negative, elcctiricity developed by tho same process remaining oil the earth. Thus, when in the heat of summer vast supplies of vapOur ascend, overhead clouds gather thickly, Iho higher ones being charged with posilivo electricity and the lower with negative. A strong repulsive force, the same as that seen in the case of the sealing wax, only on a magnified scale, is established; the strain on tho clouds becomes enormous, and occasions tho escape of a discharge which appears to the observer as a lightning-Hash. Or, if a cloud is heavily charged with positive electricity, and hangs above Iho earth, which is charged with negative, the two act ono upon the other; and as the fluids approach each other doublo flashes aro caused, ono from the earth lo tho clouds, and vice versa. When tho lightning is flashed, it causes a vacuum; and it .is the air rushing into this vacuum which produces tho sound wo call thunder. ; Incidentally, I may mention that sheet lightning is not a different kind, as most peonlo believe, but is merely tho reflection of fork lightning hidden from the observer. Thero is, of course, much speculation in photographing lightning; and the greatest pieco of good fortune in my experience occurred to me in tho summer of 1898. A tremendous thunderstorm broke over the district in tho early hours of the morning, and I rose immediately, bent on takimr some photographs. I exposed six plates, but only one ot that number had anything upon it which made it worth keeping. Nevertheless, that ono picture was a greater reward for my trouble than I was oven sanguine enough to expect, for I had "struck lucky," so lo speak, on a chance of ono in a million. It happened liko this. Having, as I thought, taken tho. flashes, I anxiously developed them the next morning, and then I saw what had occurred. The photograph in question showed the lightning in the background, but tho main thing on tho plate was a curious formation stretching apparently from tho clouds to tho earth, and very much resembling a waferspout. The same morning that I secured the photograph a cloud had burst three miles away, and the terrific downpour flooded Thrybergh Hall, a fine ancestral mansion. In short, I had photographed the cloudburst by accidont, and it is probably the only photograph of its kind in existence. Of course, chances liko this occur but once in a lifetime, but anyone proficient with tho camera will find a never-ending source of delight in picturing lightningflashes. It is always as well to know the distance tho storm is away, which will assist tho photographer in judging tho direction it is taking and tho speed at. which it is travelling. If one second intervenes bebetween the flash and tho beginning of the thunder, tho nearest part of the shining track is just 1180 ft. If five seconds intervene; it ■ is 5900 ft, or a little more than a mile away. As a rough estimate every fiyo seconds of interval liotween tho lightning and the thnnder may bo taken to represent a milo of distance. Unfortunately, it does not lie in the power of man to photograph the force of liimtmns, and show by means of permanent pictures what, this. Nature's most deadly weapon, is capable of accomplishing when used effectively, except in so far as wo can obtain photographs of trees or animals which havo been destroyed in the fraction, of a second by a flash." But to the minor freaks of lightning there is no end. For instance, lightning has been known to transport particles of gold through thick plates of silver and even of iron; and 1 remember a case which took place a few years ago where a number of pictoto frames Were entirely stripped of their silHitit b» a single flash. r.eriupf aomo- readers havo notes on

thundering and lightning which will interest those who glance at this column. If so, I shall be glad to got thorn. SOME ODDS AND ENDS. The first piece of poetry I do not. know the titlo of, but it is well worlli reading, "he following excerpts aro of a lighter nature. Recitatioi-t. (Joaquin Miller.) The bravest battle that ever was fought I Shall I tell you where suit) when? Oil the maps of the world you will find it net, "Pwis fought by tlio mothers of men. Say, not with cannon, or battle shot, _With sword .or nobler pen; Nay, not with eloquent word, or thought, From mouth of wonderful men. But deep in a wivUed-up woman's heart Of vromon that would not yield, But bravely, silently, bore her part— Lo! thero is that battle-field 1 Nojnarshaling troop, no bivouac song, Ko-banner to gleam and wave; But, oh! tlieso battles tliey last so long—• K-om babyhood to the graive. Yet faithful still as ft bridge of stars, She fighis in her waUed-up town— Fights or? and on, in endless wars, Then silent, unseen—goes down. o,.ye, with banners and b&ttlo-shot, And soldiers to shout ami praise, I tell you the hinglicst victories fought Are fought in theso silent vrnye. ° Oil, spotless woman in a world of shame I ' With splendid and silent scorn, Go baok to God as white as you came, Tho kiuglieat ■warrior born! Hep, Letters. (By Elizabeth Lincoln Gould.) " I think I'll never learn to write " Said Dorothy, 0110 day, "The kind of writing grown folks do; Mine's such an easy way. I just make little lines and clots Instead of words, and then I raalto three crones for my name—. Tint's Dorothy Hopo AVrcnn. I make big rounds for kisses, too, With straight marks on each sido That means my arms go round your nock And squeeze you hard, beside. My grandma, says most other times She needs her specs to read. But when a letter come 3 from ino She doesn't—no, indeed!" Wires. ' (By Ethel M. Kelley.) When you aro littlo and I am big I'll never work when you want to play. I'll nevor say, " Darling, nui away. Go out in tlio nice white sand and dig,'' When you are little and I am big I When you are little and I an> big I'll give you chocolalo for your tea. And sugar and marmalade—oh, you'll see, And peppermint and caramel aiid fig, When you are littlo and I am big! When you are littlo and I am big I'll never undress yon till you're through, And always I'll go to bed with you And cuddle you "comfy" and play pig, When you are littlo and! I am big! Two Kinds op Boys. I want to ask a question; Now 'splain ine this who can— > Why 'tis whenever I got hurt, I'm mother's great big man "Too large, of course, and bravo to cry!" But when I ask for cheese. Or maybe pickles with my lunch, Why, then—now listen, please— Oh, no, I'm "too litllo dear, Must «at nice vnilk and bread." I think and worry over this Unitl it lmrts my head;

And I'll be very much obliged If someone would tell mo Just 'zactly what's tho proper size A fellcnv ought .to be. NICE FOR HIS FATHER, A father sent his little boy into the country with instructions bow to load the "simple life." . After a woelc of anxiety ho received this letter"l got here all right,. but forgot to write before. A foliar and I went out in a boat, and the boat tipped over, and a man got mo out. I was .so full of water that I didn't know .anything for a long time. "The other boy has to bo buried after thev find him. Ilis mother camo and eriod all tlio. time. A horse kicked mo over, and I've got to havo eomo money for fixing my head. "Wo aro.goin*; to sot a barn on firo to-night, and I should laugh if wo don't have some. fun. I shall bring home a tame ferret if I can get him in my trunk."