B 



Tribune Extras FampJtlct Scries. 



of that peciiliar rough dotted appearance already 

 desciibed. It would seem as thouglx from this gen- 

 era] Mirt'ace there was a gradual streaking out in tlio 



neiu'liooi h 1 uf the spots. You will see that they 



spread around and across these spots, and are there 

 cjiiitc di.-tinct in character from the rice-grains in 

 tii'- Lreneral surface of the sun. 



"VYe will now have a picture from Prof. Langley, 

 Tvim worked in tin- in -iirhborhood of Pittsburgh, at a 

 bight of about 1,100 feet. lie would seem to have 

 been a'di* to rccoirni/e ilic fact that the rice-grains 

 may In- divided into smaller particles. lie has found 

 thai tin- invatcr part of the sunlight undoubtedly 

 comes fiom these little specks of brightness on the 

 FIII I :;<' of the sun, while the General level of the 

 Bun, the background on which these bright specks 

 an- proj eted, is very rnui-li darker. And the picture 

 now presented is a drawing by Prof. Laugley. It 

 would appear to be the e.isc that little more than 

 about one-hundredth part of the sun's light is given 

 l.v the dark background on which these bright 



(.peeks of li_rllt lliay lie seen. 



I have to pass on to the spectroscope discoveries 

 ly \\liieh the real nature of tl is wonderful orb, 

 whose appearance we have been considering, has 

 1). en determined I mean spectroscopic analysis. 

 "We have to consider what are the real substances in 

 the sun, and what the processes taking place on that 

 sol: a- surface. In Langlcy's picture you will notice 

 the details are on a minuter se.le than in Fr. 

 hi's pictiire. LaiiL'ley has been a'de to recognize 

 in these -rraiiH multitudes of granules, and in the 

 neighborhood of the spots you will see how they 

 lengthen out, how they se-in carried across this dark 

 region in the spot. In some places Lanyie.v has been 



to recognize on the dark background of the 

 t pot what seem to be- long filaments, the breadth of 

 v, hieli cannot be less than 50 miles. They seem to be 



iided vertically with respect to the sun, and in 

 the neighborhood of the spot some wonderful force 

 H'-ems t<> sway them toward the center of the spot. 

 These wonderful lilamcnts are thousands of miles 

 in leiiL'tn, and 40 or oi) miles in width. We will now 

 .di T tin- r. -ult- ..{ 'the spectroscopic study of the 

 Bun. 



J v, ill show you a diagram of the solar spectrum. 



You lake tin- li'jhi of the sun, and you receive it 



1hroiii:h certain triangular pieces of glass, and the 



li-ht of the -mi is spread into the rainbow-tinted 



>k, ulncli .streak is crossed by a multitude, of 



llal'k li: 



I lii- picture, to which I MW point, Is a picture of 

 the solar spectrum. On further investigation, it was 

 found that an incandescent body used as a source of 

 I'-ht, in-:, ad of basing a rainbow-tinted streak 

 < Bdbya multitinle of dark lines, threw a rain- 

 bow-tinted streak without any dark lines al all. It 



was also found that a gaseous body gives a spc!rao 

 different from this, consisting of two or three dark 

 lines. 



Here is the spectrum given by sodium in a vap"r- 

 ous condition; and that a dark spectrum wiila 

 bright lines was found to be the quality of a spec- 

 trum given by a gaseous body. 



FIG. I. 



FIC.S. 



FIG 3. 



FI a. 4. 





COMPARISON OF SPECTRUM LINES. 

 Fis. 1. Spectrum of the soiar prominences. 

 Fig. 1*. Solar spectrum. 



Vis. 3. Coat nuous snectrnm. with (inrk lines of sntlinm. 

 >. 4. Double brijrbt Hue: the spectra Ji of so limn. 



I will now call your attention to a comparison 

 between these results and the musical scale. Tho 

 red lisiht corresponds with the basa, and the purplo 

 with the treble notes, and then this rainbow-tinted 

 streak without dark is the complete scale without 

 breaks. The one with the dark lines is the scale 

 crossed by dark chords. If a musician were to hear 

 a piano played in another room out of his sight, and 

 he heard a chord struck, he would know which it 

 was, and in the same way, if you see that a gaseous 

 light gives a certain kind of spectrum, the chemist 

 knows what the light is ; and it was found that tho 

 dark lines of the solar spectrum indicated vapors 

 cooler than the sun's mass and cutting oil' a portion 

 of the sun's light. These vapors are giving out a 

 quantity of light, but being cooler than the sun, 

 around which they lie, thevcut oft' a portion of his 

 lifiht. Thus arise tho dark lines, and the chemist 

 only want- to determine the exact position of these. 

 lines to find out what elements are in the sun. 

 Thus iron, copper, and other elements known to us 

 were discovered to bo in tho vaporon? atmosphere 

 surrounding the sun. 



A well-known German physicist came to the con- 

 clusion that c.'rtain elements urivine out tho bright 

 line, spectrum, give more lines the greater I he pres- 

 sure, and that tho first lines given correspond to 

 those POCII in tho solar spectrum. The research 

 was continued at tho Mint, where it is important in 

 connection \vith alloys of metals, and Dr. Henry 

 Draper, of your country, is con t inning it. These ro- 



