Sun 



Sunshine 



SCIENTIFIC SIDE-LIGHTS 



small that it is quite clear . . . that a 

 month's deprivation of the solar rays would 

 involve the utter destruction of all activity 

 upon the earth. YOUNG The Sun, int., p. 4. 

 (A., 1898.J 



33O4. Our Varied Powers 



Derived from Its Heat All Life Due to 

 Solar Influence. Everything which moves, 

 circulates, and lives on our planet is the 

 child of the sun. . . . The most nutritious 

 foods come from the sun. The wood which 

 warms us in winter is, again, the sun in 

 fragments; every cubic inch, every pound of 

 wood, is formed by the power of the sun. 

 The mill which turns under the impulse of 

 wind or water revolves only by the sun. 

 And in the black night, under the rain or 

 snow, the blind and noisy train which darts 

 like a flying serpent through the fields, rush- 

 es along above the valleys, is swallowed up 

 under the mountains, goes hissing past the 

 stations, of which the pale eyes strike si- 

 lently through the mist in the midst of 

 night and cold this modern animal, pro- 

 duced by human industry, is still a child 

 of the sun; the coal from the earth which 

 feeds its stomach is solar work stored up 

 during millions of years in the geological 

 strata of the globe. As it is certain that the 

 force which sets the watch in motion is de- 

 rived from the hand which has wound it, 

 so it is certain that all terrestrial power 

 proceeds from the sun. It is its heat which 

 maintains the three states of bodies solid, 

 liquid, and gaseous; the last two would 

 vanish, there would be nothing but solids, 

 water, and air itself would be in massive 

 blocks, if the solar heat did not maintain 

 them in the fluid state. It is the sun which 

 blows in the air, which flows in the water, 

 which moans in the tempest, which sings 

 in the unwearied throat of the nightingale. 

 It attaches to the sides of the mountains 

 the sources of the rivers and glaciers, and 

 consequently the cataracts and the ava- 

 lanches are precipitated with an energy 

 which they draw directly from him. Thun- 

 der and lightning are in their turn a mani- 

 festation of his power. Every fire which 

 burns and every flame which shines has re- 

 ceived its life from the sun. And when 

 two armies are hurled together with a crash, 

 each charge of cavalry, each shock between 

 two army corps, is nothing else but the 

 misuse of mechanical force from the same 

 star. The sun comes to us in the form of 

 heat, he leaves us in the form of heat, but 

 between his arrival and his departure he 

 has given birth to the varied powers of 

 our globe. FLAMMARION Popular Astrono- 

 my, bk. iii, ch. 3, p. 245. (A.) 



33O5. SUN THE SOURCE OF TER- 

 RESTRIAL LIFE Three Necessary Elements 

 Supplied Light, Heat, and Actinism. Our 

 sun sends forth rays which supply three 

 very different requirements of living crea- 

 tures, animal and vegetable, peopling our 

 earth. Without light, we should all before 



long perish miserably; and the sun's rays 

 supply us with light. Without heat, we 

 should be even more quickly destroyed; and 

 the sun's rays provide ample supplies of 

 heat. But besides light and heat, we require, 

 directly and indirectly, that chemical action 

 of the solar rays which has been called 

 actinism. Without this action the air we 

 breathe would be loaded before long with 

 pestilential vapors, which would destroy 

 the lives of men and animals; plants would 

 wither, and presently die; the whole earth, 

 in fact, would soon be the abode of death, 

 as surely, tho perhaps not so quickly, as 

 tho the sun had ceased to supply either 

 light or heat. Now at present these three 

 forms of energy are exerted in certain pro- 

 portions admirably suited to our require- 

 ments. Dividing the solar rays according 

 to the position they occupy with reference 

 to the spectrum, we have from the red rays, 

 and from dark rays beyond the red, the 

 chief supply of heat; from the whole visible 

 spectrum, but chiefly from the yellow por- 

 tion, comes the supply of light; and lastly, 

 the violet rays and the dark rays beyond the 

 violet afford the chief supply of actinism. 

 PROCTOR Our Place among Infinities, p. 212. 

 (L. G. & Co., 1897.) 



' 33O6. SUN'S CORONA YET A MYS- 

 TERY Limited Opportunities for Observation 

 Three-quarters of an Hour in Thirty Years. 

 Our knowledge of the corona remains very 

 incomplete, and if the most learned in such 

 matters were asked what it was, he could 

 probably answer truthfully, " I don't know." 

 This will not be wondered at when it is 

 considered that as total eclipses come about 

 every other year, and continue, one with 

 another, hardly three minutes, an astrono- 

 mer who should devote thirty years exclu- 

 sively to the subject, never missing an eclipse 

 in whatever quarter of the globe it occurred, 

 would in that time have secured, in all, 

 something like three-quarters of an hour 

 for observation. Accordingly, what we know 

 best about the corona is how it looks, 

 what it is being still largely conjecture. 

 LANGLEY New Astronomy, ch. 2, p. 59. (H. 

 M. & Co., 1896.) 



33O7. SUN'S HEAT PRODUCED BY 

 CONCENTRATION Probable Continued Du- 

 ration of Solar Light and Heat. For how 

 many ages has the sun himself shone? On 

 the hypothesis that the nebulous matter 

 was originally of extreme tenuity has been 

 calculated the quantity of heat which must 

 have been produced by the fall of all those 

 molecules towards the center to the conden- 

 sation of which was due the birth of the 

 solar system. Supposing the specific heat 

 of the condensing mass was that of water, 

 the heat of the condensation would be suffi- 

 cient to produce an elevation of tempera- 

 ture of 28 millions of degrees centigrade 

 (Helmholtz and Tyndall). It has been 

 known for some time past that heat is but 

 a mode of motion; it is an infinitesimal vi- 



