The Comet.

Timaru Herald, Volume XIIIC, Issue 14216, 4 June 1910, Page 2 (Supplement)

The Comet.

UP TO EXPECT AHONS. , p omot, says Key. P. Ay FairI'.IUUS., in the "l'rcls/' hall.u more than realised tho most sunSnn® es r t: !^ iou "- 11 Jlus bot-n a imnr +f l M s l ,ectacl «-'. As it drow - ai tlie earth, it covered a vast return in the sky, but it was paler than v hen it was 40 million n „| ( , H alvily On the morning of tho 19U), when Ik was not more tJimi two million of miles distance it resembled a, long sheet <>i cirrus cloud. It was ninny deirl'ces wide, ),i,t not so ] o „g to the eye as it had boon on the previous evening. \\heu we sou a city Jrom a mountain a. c'on.sutcrublo distiinc-c it seems to bo covered with haze or log that seems Jess dense, and when we get into it w© cannot see it at all. It is so with tho tad of the comet. There was no appearance of any kind of change in the atmosphere during tho hours of immersion jn the tail stuff. Our view was obstructed by flying clouds, hut the slv.y retained its en.stomary SunKct jukl sunrise Jioxt morning bi<traved 110 unusual symptoms. The rays reddened the mists in the lower «i'r, but there was no tender pink of ruby in the high atmosphere. On the morning nf the 20tli there was a littlo rus, nut nothing unusual. Radiation pressure, M*liioh drives out tho tail of the eomet is said to bo most effective when tho motes of lightduvon mutter arc 0.000016 of a. millimetre m diameter. "Of these 470 billion make one cubic centimetre (of water say) and vet each particle contains !)6 million molecules. The mote must, however, reflect all the light that lulls upon it in order to receive the lull thrust of the ray. Should it let any light pass through, or absorb any, it would be like a roll of netting in a wind, compared with hollow drums of the .siime shape and size. "Wlr'U none of the wind can get through, it gives its beet push. For the _ most part, . the thrust of lip;lit on suitable particles will bo ton times the pull of gravity. In specially favourable, conditions, however, it may bo 19 times as powerful as gravity. It is these specially sensitive particles that make the bright, short tails sometimes vseon in front of n comet's main tail. The push of tho light diminishes like gravity, with the square of the distance from the sun, so that velocity of flight will bo maintained. Arrhenius supposes tliat tail stuff and •lust driven from the sun continues its (light until it is captured by a planet, star or nbulu.

The experiment wh.ieh proved the propulsive power of light was on this wise. The spores of a certain fungus are spheres of suitable size. A lot of thess were Leafed to a. red glow, so as to turn them into tiny balls of spongy carbon They were enclosed in a. test tulie, sliaped liek an hour-glass. Tbe air was exhausted and the tube sealed, but not before some omery powder bad been mixed with the spongy canlion spores. The glass was then ,s"t so that the content# would run from tbe upper lobe to tho lower. Just under thy neck a powerful beam of light was shot through the glass. The emery powder fell straight. down, but th» earbon spores were dashed against the side toward which the beam of light was streaming. Comets, are, believed to consist mainly of iron, sodium, carbon, hydrogen, and nitrogen (as cyanogen) in that order. Tho last consists of the lighter elements, and may therefore become exhausted. As metororites Tia.ro been seen morn than 100 miles above the earth, thin is taken as a proof that there is far above that height an atmosphere capable of resisting the flight of tire meteor and firing it with friction. \rrithenins. Links that solar dust, and therefore, comet dust would be caught in tho outer fringe of the atmosphere at a height of 250 miles. The additions to the earth's weight from shooting stars is variously estimated from 20,000 tons to ten million tons a year . The amount of solar dust intercepted is put by ArrLenixis at 200 tons a year. Tho era ins from Halley's comet must be reckoned in ounces. The results naturally corresponded with the causes. The solar dust causes auroras, and nl.so the formation of very high cirrus clouds. Cirrus clouds have a. distinct relation to tbe sun-snot maxima when the outnnt of n<>l»r dust is greatest. It is curious that Yogel finds that during the maximum Rim-enot Jupiter is whiter thin at other times, and reddest 'at minimum periods. This is taken to menu that' the maximum siiot and dust nen' n d covers him with white fent-bcry cirrus clouds.

No excess of cirrus clouds was observed on the nigh+ "f tb" 10th or t l '" nwriiing of the 20th. This mav bo taken to nrove that the amount, "f cometic dust in the upper air was tr'fling.

During the last two years Victoria has suffered from what physicians of an earlier time would have called a "period of epidemic constitution." 7?pidemics of scarlet fever, measles, diphtheria, and other child diseases have been nrevalent, thoiiEh, hn.rmilv. not cf excessive severity. _ "Within the last few \\ee;cß u.u epiueinic. of mumps lias h"i;n rugr.-i" through the schools, and latterly has manifested itself to an unusual extent among adults. As one attack of mumns is held by medical authorities to mean practical immunity for tho •rest of the patient's life, tho assumption is that those adults who are now Buffering are young people who have grown uo in a period comparatively free from outbreaks of the malad*.