18 



KNOWLEDGE ♦ 



[Nov. 4, 1881. 



COLOUR OF SUNLIGHT. 



PROFESSOR LANGLEY throw out, scvcm! ycnrs ago, tlic idea 

 tlint oar xun is in ivniity not ii ^vllito sini, but a bluo one, hiu 

 apparent whitpncsa being duo cliiolly to tho absorptive action of 

 \\\p own ntmoaphoro, but finrtly to that of our own air. It should 

 bo noticed, in considering this view, that our sun is ])robably akin 

 to the stars which wo roRnrd as yellowish. Capella, for instance, is 

 decidedly yellow by comparison with Vega. The spectrum of Ca- 

 pella has been shown by Dr. Henry Draper to be so similar to that 

 of the sun that tho eye can detect no difforonce. .\rcturus, whicli 

 is somewhat more markedly yellow — and, indeed, is regarded by 

 some as orange-yellow in colour — has a spectrum very closely re- 

 sembling that of tlio sun, but still not exactly the same. Tho gi'oat 

 value of Dr. Drajjcr's evidence on this point, like that of his 

 evidence rcsjiecting the presence of oxygen in the sun (as sliown by 

 the comparison of tho solar spectrum with that of our own air), is 

 that it can be studied by all who choose to examine the photogr.aphs 

 which he has obtained of the spectra for comparison. On the 

 same small piece of glass are shown the spectrum of Capella and 

 tlio spectrum of sunlight reflected from the surface of a planet, 

 and the identity of the lines belonging to the two spectra can be 

 seen at once. N'ow, Professor Langley, pursuing tho idea which 

 he threw out several years since, lias been able to show that 

 oui- sun, though wo regai'd him as a white sun, and though, 

 seen from a greater distance, so that ho appeared as a star, ho 

 would probably ajipcar yellowish, is yet a blue, or at least a bluish 

 snn. We see that the sun appears red, or orange, or yellow (accord- 

 ing to the state of tho aii') when setting — that is, when seen through 

 a long range of our own atmosphere. Such action as our air exerts 

 on the sun when he is high above the horizon is similar in character, 

 though less in degree; it serves, therefore, pro tantn, to render tho 

 disc of the sun yellower than it really is. Again, the edge of the 

 sun's disc is markedly less luminous than tlic middle, though 

 to ordinary eyesight tho difference is generally rendered undis- 

 cemible by the sun's great lustre. Of course, in reality the same 

 amount of light is omitted from that part of the solar surface 

 which at any moment lies near tho edge of his visible 

 disc as from that part which lies near the centre. The 

 apparent difference can only be due to the effect of absorption 

 exerted by the solar atmos]ihere— tho line of sight passing through 

 a greater range of this atmosphere when directed toward the edge 

 than when directed tciward the middle of the disc. (In passing, I 

 may note that the difference of absorptive action is proof, not, as 

 Kirchoff erroneously supposed, of the depth, but of the relative 

 shallowness of the solar atmosphere.) Now, anyone who studies a 

 photograph of tho solar disc — as, for instance, that excellent 

 photograjih by Rutherford, which forms the frontispiece of 

 Schiller's German translation of " Lo Solid" — will have noticed 

 that the darkening toward the edge is much more marked there 

 than it is in the ordinary telescopic disc of the sun. It follows that 

 those rays which produce the photographic imago of tho snn 

 (chieBy the blue, indigo, and violet ray.s) are more affected by the 

 absorption of the solar atmosphere than those which form the 

 ordinary visual image of the sun. His atmosphere then acts more 

 strongly to absorb the rays belonging to the blue end of the spec- 

 trum than the rays belonging to the red end. The sun's apparent 

 colour, therefore, is less bluo than his real colour. If liis atmo- 

 ajihero were suddenly removed, he would change from his present 

 white or whitish-yellow colour to bluish, or perhaps greenish, pre- 

 cisely as the setting sun, if the air between the eye and him were 

 suddenly removed, would change from his apparently ruddy hue to 

 the white colour of the overhead sun. In this way it has been, 

 only by detailed experiments instead of by general reasoning, that 

 Professor I.angley has established the theory that our snn is really 

 blue, his apparent colour being due to tho effect of absorption 

 exerted by his atmos))herc of vapours, chiefly metallic. 



THE TRIBVNE RIDDLE. 



THE mystery of the Tribune Building* has long baffled the 

 inrestigations of our most learned archaeologists. I'utting 

 aside as unworthy of consideration certain wild theories of its pur- 

 pose, there remain three leading theories, each one of which has its 

 able advocates. By these we are told that the building was designed 

 either for a tomb, or for religious purposes, or for an astronomical 

 observatory. 



Tho first of these rests on a comparatively slight foundation. 

 Tho most elaborate research has failed to show that there is any- 

 thing buried beneath the Trxhime Building, except beer. 



• The oBice of the New York Tribune. 



TIio learned volume written by Prof. Veranda Brown in gnpport 

 of tho theory that tho Tribune Building represents tho history of 

 tho Jewish and Christian religions, and contains a precious projihecy 

 as to the future religious belief of mankind, has a certain degree of 

 plausibility which will always commend itself to imaginative men. 

 As is well known, tho plan of tho building is unlike that of any 

 other architectural work, in tho curious and arbitrary way in which 

 it is divided into different stories. The lower part consists of four 

 stories and a basement. According to Prof. Broivn, this basement 

 represents tho patriarchal period before the time of Moses, and tho 

 four stories represent tho Jewish nation under Moses, under tho 

 Prophets, under the Kings, and under the Roman Empire. The 

 last story is smaller than the others, thus typifying the declining 

 condition of the Jewish state, and the marble capitals of its pilasters 

 indicate the luxury and splendour of the Roman Empire. Above 

 the Jewish division of the building we find a second series of 

 three stories, rcjiresenting the first three centuries of the Christian 

 era. Tho uppermost one of these is gorgeously ornamented with 

 polished granite columns, with Byzantine capitals— constituting 

 an unmistakable reference to the conversion of Coxstantixe, the 

 lixing of his capital at Byzantium, and the triumph of the 

 C'hrietian religion. Next wo find three more stories, each con- 

 taining five windows. These typify the fifteen centuries which 

 have elapsed since the conversion of Coxstaxtlve, and bring the 

 record of the Jewish and Christian religions down to the present 

 time. 



Where the seventh story, or the third centurj- of onr era, begins, 

 the facade of the Tribune Building is divided into two large masses, 

 one being precisely twice the width of the other. These nndonbt- 

 edly represent the division of the Christian world into the two great 

 Churches — the Latin and tho Greek — the beginning of which 

 division really dates back to the rivalry between the Bishops of 

 Rome and Constantinojile. Between these two great divisions rises 

 the tower — a ejuadrangiilar structure, with clear-cut angles, and 

 standing boldly out into tho light. In this tower we recognise 

 Protestantism. Smaller in size than either of the two great di- 

 visions that represent the Latin and Greek Churches, it reaches 

 nearer heaven, and secures a greater share of both sunlight and 

 clouds. 



The upper part of the tower is, in Prof. Veranda Brown's opinion, 

 prophetic in its teaching. Both the tendency of Protestantism to 

 bring all things to the bar of reason, and the refusal of any two 

 Protestant bodies to agree in their views of what is true, are pre- 

 tigurcd by the clock which occupies the upper ]iart of the tower, 

 with its four faces that so stubbornly refuse to make the same pro- 

 fession of faith as to the time. Still higher than the clock wo find 

 the lightning-rod. There the tower has reached its fullest develop- 

 ment — ending in a point — signifying " nothing," and a lightning- 

 rod, of all things the most thoroughly scientific and materialistic. 

 Prof. Verandah Brown, who is a pure rationalist, accepts with some 

 scientific enthusiasm this architectural prophecy of the fate of 

 Protestantism. 



The astronomical theory of the building is ably advocated by 

 Prof. Pritchard Roctor. He maintains that had the builders in- 

 tended to erect an astronomical observatory, they would have designed 

 a building which should liave been both massive and high. Both of 

 these conditions are found in the Tribune building. They would 

 also have constructed a long, narrow tube of masonry through 

 which to observe the stars. We find precisely such a tube in the 

 Trib\ine Building, although the ignorance of the present day has 

 perverted it to the use of an elevator. They would also, says the 

 Professor, have constructed a subterranean cliamboras a receptacle 

 for water. The Tribune builders buildcd even better than tho Pro- 

 fessor knew, for they made a large subterranean chamber for the 

 reception — not of water, but of beer. From these censiderations ho 

 draws the conclusion that tho Tribune Building was designed for 

 astronomical i>urposes, and incidentally remarks that the arguments 

 of Professor Veranda Brown are fallacious, inasmuch as he forgot 

 to include the coal-cellar in his calculations, and the coal-cellar 

 cannot possibly be brought into any intelligible relation with the 

 Jewish comuionwcalth. — A'etc Yorfc rimes. 



Ultimate STRrcTUKE of Bodie.s. — "As matters now stand," says 

 Mr. U. C. Sorby, "we are about as far from a knowledge (by 

 vision) of the ultimate structure of organic bodies as we should be 

 of a newsyiaper seen with tho naked eye at a distance of one-third 

 of a mile." 



Poxd's Extract is a certain cure for Khcnmatisin and Oi>ut. 

 Pond's Eitract is a certain cnre for Hieniorrhoids. 

 Pond's Extract is a certain cure for Nouralpic pains. 

 Pond's Extract nill heal Bums and Wounds. 

 Pood's Extract will cure Sprains and Bruises. 



Sold by all Chemists. Qet the geouine.' f Adtt. 



