SPECTRUM ANALYSIS

Globe, Volume IX, Issue 1352, 14 June 1878, Page 3

SPECTRUM ANALYSIS

As'rovorr-y is at once the oldest and the newest "i in.' se.i •iires. In a rude way, it v: s, a-' we '.no-v, si.uditd in the very cradle '•'. the iii'.. >ri !'.•':■. Our first glimpse of the most; :, .e : ;.!ii, ;;.;:ej\s reveals them as starg;Zers, moo*-■:.;■' :'\ aslronomers. In tlieir

iioiplo rvay they ffli. the awe and the wonder wiili which Ktiiil says ho was filled whenovor ho looked upon the starry heavens. Wo have just called attention to Mr Norman Lockycr's new and striking book on " Star-gazing." By the last mail another new book from the same pen has como to hand, Mr Loekyer Ins long been known for his knowledge of and devotion to the new branch of astronomical research —spectrum analysis, which has already attained to the certainty and dignity of a science. The spectroscope is now spoken of in the came breath as the telescope. And with good reason, as by the invention of the telescope the universe was almost infinitely extended; so by the spectroscope matter or like matter is found to be acting in lil.c maimer everywhere. The spectroscope shows there is a certain oneness in the diversity of the universe, that tbj matter of the earth iq akin to. tha other planets and even with the most distant stars; and tins is a discovery equally as valuable and is likely to be as fruitful as the invention of the telescope or the diu'ovory by Newton of the great law. of universal gravitation. Mr Lockycr, like some other distinguished men of seier.co, ba« the gift of luminous exposition, lie knows what he knows, and what is rarer arid better he can imparl his knowledge to others. Tn these 'studies' he places himself by 'he side of the eager learner, to whom every stage of a complex subject is made delightfully plain. A few passages from the first chapter will show how admirably the special t.'/wV.>» ft*e elucidated, especially by famiuuv facts in the kindred sconce oi sound. " The prism tells us {•■hat a beam of white light not a simple thing, but that it may be likened toarope with an infinite number of strands. It", for instance, hy some concerted action ill the kevs

of a piano are pressed down, a certain sound results, made up of a combination of nil the sounds upon the key-board. This then is the sound analogous to a ray of light. The reasoning which lies at the bottom of all the new researches which have mad:? us familiar with matter millions nnd millions of miles us as wc are with tho matter around iv.>, -arises from the perfect establishment of the idea, that a ray of white light is universally composed of wares of light of various lengths, just as that noise from the piano was ah o composed of different true

musical notes, that h to say of waves of sound of various lengths; and that each light of special colour is composed of a single wave length or of a special combination of wave lengths." "If then instead of letting the white light which we get from the sun travel through a a fine slit straight from the sender to the receiver, we insert a prism and lens in it 3 path, we observe one effect of a

complex natnre ; the light is thrown out of its course, and instead of the lens forming a single imago of the slit through which' it emerged, as it did before—instead of the image of the slit, which wa3 white and small before—we shall have a rainbow colored image stretching across the screen. By adding a second prism to the first we get the same effect increased, as might be expected. That rainbow coloured band is the spectrum." (33). The difference between the continuous and the broken spectrum—the one coming from white and the other from colored light is then made clear. Each separate element has its own distinct and differently placed lines. Each clement having thus its wellknown spectrum, it is comparatively easy with the proper instruments to find out not only what the stars are made of, but about what temperature they exist, the nature and extent of their atmospheres, and the way in which these atmospheres vary from cycle to cycle. The spectroscope would seem to be bidding fair to disclose even greater wonders than either the telescope or the microscope. By its means, as Mr Lockyer says, "it is probable that in a few years wo may know very much more about matter very far removed from our planet than wo do of a great deal of it on the very planet itself on which we dwell." The International Scientific series of books has now reached its twenty-second volume. Of the whole it may be said that none are more readable and valuable than the first and the last—Tyndall's "Forms of Water," nnd Lockyer's " Studies in Spectrum Analysis."