Show I HA HALLEY'S LL EY S C COMET 0 M E T By FREDERIC CAMPBELL Sc Se D. D r I President of the Department of Astronomy Brooklyn Institute J J It ht 1909 by Frederic Campbell C 1 In preceding articles we ha have c in- in into tb the appearance distances s l dates c course and history l that stupendous object Halley's net which Is fa just unsheathing uns its frd rd to suspend it over ovo- Ol our j guilty luiJt ids de de for months month It is no tinie notime time lo to lolie toe lie e an in c investigation estimation into tho nature p to so extraordinary an nil object Te impressive c thins thing about a 1 comet om omIt its It I long sweeping tail I a alleys alley's II C s sI s I been seen to lo reach a length of t grees ces is equal to lo a line Huc of full fun moons In n appearance this i sot t unlike a which thich cast I rOil a landscape lS illumines nil all the seit particles of dust and hith bieh bap happen n in it its J mH giving ing in i un an pr of substantiality l h far farOU OU OUe e facts It is is' is perfectly cas faS for or a aA I ild A to walk through h th the beam t l of a and ann to t its full form force pon a falling lea leaf would not Jot disturb nO the least Jt It i i is somewhat t to so with a t comets comet's Mil iI It is one oue of the most tn Ml si things in n tho tim universe The t tars can un he bf r distinctly i see seen 1 n IOD of miles of at its thickness Un in Unu inu u one 26 18 1819 9 the earth Nut h passed through h COID comets comet's t tail without nn un result rhe ery cry beg Lt Vacuum s cure in ill t the In laboratory lab lab- 11 oratory is s as i IS solid millstone O pa d with ith the tho density of a com com- t tail It is is therefore manifest st that I when n we caw su upon neIf an nn object p C e arc r looking upon next to In e ii tf f co j r crit is and in JD t I C October o 0 12 1835 lO a n old drawing 1 order to k oW what it is vre we stud study the nature of tho the comets comet's head from which it proceeds i The solid part of a comet cornet is its nucleus nu cleus dens or core con This This-is at nt tho center of its head and shows more moro brightly than the T rest t. t A large part of tho the head bead is nearly nearh as unsubstantial as lS tho the tail and mn may inay bo be likened to steaming vapors Because of the nature of these it is is to s secure nn an accurate of the tue nucleus as it would ho bo to jud judge of the sizo size of skull lJ beneath its itA corona of wa waving hair I But when or harleM b A. A Young sa says ar s that tho the nines mass of the thu heat head of an average II large e comet like lite Halley's Hacy's may maybe maybe mw be as equal to a a. hn ball of iro iron of 0 sJ diameter it is manifest that hero here we have o something truly sub sub- The nucleus then i i the thc real comet And this is conceived of or not notus us JIM n ii solid but lUl as s a mas mass of objects ob ob- ob of ot uncertain size ize held to together Halley's Comet October 29 2 9 1835 From an old drawing l by their mutual 11 I itt lion and all moving mo un under er the tho in influence of the tho sun o these c came caine and bo how bow t tb the bp j happened a to be lH no one knows nut Hut the tho substance of which they arc composed arc no identical with elements clement a with which we are arc familiar carbons and various m metals respond d to tests iron tests iron magnesium etc and ctt and as matters develop with tho the approach app of a n comet to the sun the hydrocarbons break brcak up into soot and smoke which i is illuminated by br the tho sunlight in which bien it travels Far away away the comet no light ht nor tail tn the thc in influences l of the sun flun atc are felt too top feebly ut nt fo so great reat distance But with the ever e increasing speed of it itt approach b is is a n rapid increase of the sun suns sun's s 's energy imparted to it it to so o that tho the ml nucleus hitherto cold and dark develops its ts hazy huy head hend and 31 is first seen scon as ns an nn indistinct nebula thou then tho the tail I is thrown out and developed as w well we'll 11 an as more fully displayed by rca rca- son Eon of its itt near approach Since the carth lies lies so near r the tho sun in the celes celestial liu I a vastness s the tho comet a approaches sun and I nd earth at the tho same annie time lIco at first its tail lies behind the tho head bead andis and andis i is seen leen nearly lengthwise hen it passes our Il globe be in either direction on we view yiew it sidewise and obtain t the tho c fu full benefit bCD fit of its entire length of millions of miles The development of the tail 1 is IS due to the rapid increase of solar beat heat and iI 34 3 4 tI- tI I Hallcy's Halley's Comet January 28 1836 From au an old drawing perhaps of electricity driving out out- outgases gases from the which are aro repelled in iii ins s space pace As the he tail is always turned away from tin the sun it is iu i clear that some omo force c proceeding from tho the sun is accountable for it it It cannot he be like Jie a t trail ruil of 01 oi moho o loft left behind a locomotive for 0 a thc comet docs 1008 not I travel tra in ill any resisting medium ium and ana is I actually preceded 1 by yi its tail when retreating re- re retreating re rc- treating into space One Oue of our most is i that of tho the force exerted by light it- it Xo No Ira Ira s time tons of light j ht pressure arc are ed received l by thu from tho the sun and its law hw j is is that this force f rapidly i increases with tho the di iii- division vision of r tho tIm object into smaller par par- ticks s. The substances expelled from the nucleus of a comet cornet bv iho tho sup gun constitute con on the mos finely divided matter conceivable hence the tho most sensitive to the tho action of light Sonic think that there thoro is nn an actual bon bombardment of these particles by b corpuscles proceeding proceeding proceed proceed- i ing I from the sun with enormous jd l. l Hence they the are nrc swept s back n k into space in the form of a u tail taiJ whose whole light is chiefly if not reflected turn sun sunlight Ji light ht while that of ot tho the head bear i is is partly reflected 1 and partly tho outcome of en- en n n orgies set into action by br tho the sun suns Suits in in- in fluence Comets sometimes s run so close to tho tue sun Bun that they aro are torn to pieces b by tho the tidal influence of its tremendous 5 comet is one of ot these gone Jone beyond recovery anti m l now suPplanted b bv by the he stream of fo following its former course Flue Tho great c com comet t of 1882 ran s so 1 o near the sun as s to brush its coronal streamers stream stream- ers era and it BO so felt the force of of- the suns nuns attraction when so 80 close lose that it went to pieces before our 03 ces CB breaking breaking break break- in ing into no less Jess than five separate com corn cornets comet comets et ets each throwing out its tail after the pattern of the tho original It is thus that in a number of instances meteoric streams arc re e recon recognized as the remnants l f J Comparative Comp ve sizes 61 f Neptune and the earth To Neptune is given the honor honorof of having ha c captured Halley's Hallcy's comet Drawn by the tho author I of old comets th the old oM paths cud aud steadily exhausting them thum- cs selves by hY sell self immolation in iu tho ca m Dr graphically graphical phi demonstrated tho the relation of meteors to lo comets when on OUA on OUR occasion n. n he extracted ex ex- gases fi from meteorites that laud had fallen to earth carth and with them the theatre of tho tito I loyal iu |