" THE NEW ASTRONOMY."

Nelson Evening Mail, Volume XXVI, Issue 75, 1 April 1892, Page 3

" THE NEW ASTRONOMY."

A CHAPTER IN POPULAR SCIENCE. [BT 818 BOBEBT BAIiL.] * Ia tho Jacaary number of the Fortnightly Review thew is a fascinating paper by the Irish A6trouomer-Royiil, which he entitles as above.

THE MOVEMENT OF " PI.XKD STABS." The iußtrnment of the New Astronomy. ifl, of oooiae, the" speotroscopo ; and tho aovelfcy of its use lies in this ; that, whereas it was formerly üßed to ascertain the chemical constitution of the starts, it ia now being used . to determine their movements. By. way,' of introduction to his subject, Sir ttobert Ball reminds us that " tha ordinary expj&si&ion, fixed star, ia & mißnonier. When the plaoa ol n mat has bean accurately determined fay measurementa made with the meridian circle, and wheo^ after the lapeo of a number of ysjrs, the place of the eamo star ia again deteiminei by obsyrvaticn, 'n uot nnlrequently happsua that tho two places disagree. Th» explanation is, of oourße, that the etui has moved in the interval, And it is infioiteiy improbable that any reaily fixed star exist*." THE GAP IM TUB ASTBOMOMBII'B AKMOhrYj Now, the ordinary method of determining the movements 0.! stars is by the telescope nd the meridian cirole. But there are some movements, Sir Robert points out, whioh cannot be thua measured, Theeo are the oases when a star happens to bn darting directly towards tho observer or directly from him. In ouoli oases the teleecopio method is inapplicable, because the obaarver would not notice any change in the star's position, "It is just here thut the Bpeotroaoope o^mes in to till the vacant place in the armoury of the astronomer," Tha way in whioh it does this, whioh Sir Robert Bail proceeds to explain, iB, as ho remarks iaoidentally, ' a beautiful illustration of the extent to whioh the different brauohea of physical eoienca are interwoven." THE DEMON STAII. Aa an instance of the extraordinary re« suits obtainable by the new method, Sir Robert Ball describes how a&tronomers have at last got equul with the vagaries of Algol— the Demon Star. Now, the peculiarities of this celeatir.l demon are that fur two duyß and tea hours the stur remains of uniform lustre, being ranked about the eecoud magnitude ; then a decline of blight ness sets in, and iho btar in a few hours pares with three-fifths of its brightness, These obangea are vieiblo to the naked eye, and have been known foe centuries. But nobody Unaw how to account for them. Tua theory whioh held tha field w&b that the lobs ot light mast be due to aa eolipso of the brilliant star by aome deik oompauion, But Ibis theory waa not compatible with the observed ftotß, and at last Yogel has made the BSar reveal ita mystery ;— Applying the improved epeotrographio process to Algol, he determined on one night that Algol was retreating at a speed ot twenty-Bis miles a seoond. Who he ropeated his observations he found that Algol was agaia moving with the same velocity, but this time tha movement was towards the earth iustead of from ic. Now, it is impossible for a Star to run along a straight line for a certain distance; atop, turn back, and again retra.e its movement, stop, aud again rtfcuru. feuoh movement is Bimply forbidden by tho law a of motion. Bub ' tb,ore . ia ao objection to the supposition that Algol is moving in a path which ia nearly, if not exaotly, a circle, Iv this it wouMonly be jaofiug rb does the the moon, or tho eartb, or any of tho other plantts. It will be only ueues&ary to suppose thai tho plane of ihu orbit of Algol is directed so that it passes uear the earth. Daring the deaoriptioa of one Bgmioirole Algol will be coming towards us, while during the other aeuuuuole it will be goiug from us, aud thus the observed faots of tho movement are conciliated with tue laws of motion.

iai3 DEHCN'a INVIBIBLB COMPANION. BuUbo rtsiiits ol the l\uw AaUouomj in ooDDeoiioD with Algol are nol exhausted yet, tiuoh v movement as has been above proved adDiito^ol iiO oiher iDierpre'.&t'um ta\e that there inueb be another mighty body ia thu immediate vicinity ot Algol. We have already seen reason to believe in the possibility of the presence of suoh a compaaion for tho Demon Star, simply from tho ißct of its variability. There cannot be auy longer a doubt thuc tho mystery iinsi beeu aolved. AJgolpnustbeatteuded by a companion Btar, whioh, if not absolutely as devoid o£ mtrinßio light aa the earth or the moon, is nevertheless dark, relatively, to Algol, Oraoa in eaoh periud of revolution ibia obeoure body intrudes between the earth and Algol, cutting cfi a portion of the direot light Ciom the star, and thus produuing the wehJuiown tStioi, Hero wo have each a remarkable ooriourrenco between the faotoo! obaervalion »nd th 6 !ima cl dyuamio that it ia impoßeiblo to doubt the explanation they provide of the variability of this famous star, WEIGHING THE UNSEEN, But the New Astronomy nob only proves the existence of this unseen star ; it mea< nures and weighs it as well. '' Here is an object whioh we have never aeen ( and apparently never oan expect to nee, but yet we nave beau able to weigh it, to meaauro it, and to determine its movements,"