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light, and its movements are controlled our atmosphere and as it comes to the by the earth's magnetic force, in a man- surface of the earth. ner analogous to the influence of an arti Prof. A. E. Dolbear has lately said: ficial magnet upon a current of electricity “For a long time it was believed there circulating around it."
were three different kinds of ether waves,
known as heat, light, and actinic rays. DARKNESS AND COLD OF SPACE. The latter were supposed to be the ones
that produced the chemical action on To see the atmosphere of our planet, photographic plates, while light consisted and the planet within the enveloping sea of rays of a different kind, capable of of air, an ocean of mingled gases at the affecting the eye. It was discovered, bottom of which we have our life, it may however, that the same rays that can probe noted first that all space surrounding duce vision can also heat a body, and us, even that through which we look to also do photographic work; and what any the sun by day, and in our hottest season, ray can do depends upon the kind of matis an absolute of darkness and of cold. ter it falls upon, so that all rays have If we could be placed in open space some similar characteristic properties. The distance beyond our atmosphere we would discovery makes it plain that there is no see the sun, through total darkness, as a peculiar kind of ether waves which can bright orb, but not apparently giving any be called light, as distinguished from light to space, and the earth as an orb other kinds of ether waves. What is also, simply bright with reflected light, called light is a physiological phenomenon but not light-giving. Our sunlight by and has no existence apart from eyes. day and our moonlight by night are phe. So well assured is this, that the serious nomena possible only within the limits of proposal is made to banish the word our atmosphere, and not possible any- light' from physics.” where in the depths of space. The rays The differences which have been noted, radiated from the sun through space do and correctly noted, are those of waves not constitute or carry light in any way varying in amplitude, those of least amwhatever, until they encounter conditions plitude on the extreme right of the solar such as those of the atmosphere surround spectrum, and noted as actinic with refing the globe, and produce among those erence to their chemical action, and those conditions the effect which we know as of the greatest amplitude on the extreme light. The agency acting from the left, and noted as heat waves, because of sun through space has what are un- their marked heating effect. There may derstood as vibratory effects of very wide be heating effect, and in fact must be, variety as to the comparative rapidity of from any of the waves the whole length the vibrations produced, and the whole of the spectrum, and there might be breadth of these effects is called the solar chemical effects at any point of the specspectrum. As we pass from right to left trum, but the fact remains that, while across the page on which we represent notable chemical effects begin on the exthis spectrum, a considerable length of it treme right of the spectrum, marked has vibrations too small to give the effect heating effects fall far to the left. Thus, of light to our eyes; then we begin at Tyndall found that the quality of the violet and pass through the colors to red; heat radiated by a flame of hydrogen is and beyond that, for an extended section almost exclusively ultra-red. The genof rays of very marked power, we have an eral distinction is, therefore, fully warinvisible spectrum of perhaps ten times ranted, which notes as specially chemical the length of that within which we get the the right-hand part of the spectrum, and light effects from violet to red. This as specially that of heat effects the leftplainly reveals the fact that even within hand end of the spectrum. And there the conditions of our atmosphere light is is no question whatever that in a particthe effect of a very limited section only ular place of the solar spectrum, and only of the broad spectrum of rays which come a short space, occur waves which are of through space from the sun; and research the right amplitude to give the light has demonstrated that even this narrowly effect to our eyes. limited pencil of rays gives no effect of Tyndall found that of the emission light as it passes through space, and only from a dazzling electric-light, one-tenth becomes light-producing when it enters only consists of luminous rays, and that nearly two-thirds of the rays from the effect for filling space is limited to the electric-light which actually reach the near part of space surrounding the earth, retina are obscure. Of the emission from the vast range of space at a distance from the most brilliant portion of a gas-flame, the earth being without what we know he found that one-twenty-fifth only con- as light. sists of luminous rays; and that of the And what is true of the light effects of radiation from platinum, heated to white the sun's rays is also true of the heat ness, only one-twenty-fourth consists of effects; they are entirely unknown in the luminous rays.
regions of space between the sun and the The reason for this, although it has earth. An ascent into the air in a balnever been noted, is a simple one. The loon to the height of seven miles, at no eye is prepared for seeing by the action matter what season of the year nor with of the oxygen of respiration, and those what heat at the surface of the earth, waves serve to give the effect of light to shows a beginning of intense cold, the the eye which synchronize with those of terrors of which must steadily increase as oxygen. Sachs shows how in plants the we recede from the lighted and warmed evolution of oxygen from the organs con- surface of our planet. taining chlorophyll depends on a certain the air, in a much .arer and weaker range of wave-lengths in the spectrum of state than close to the earth, may last to light. He shows the extremes between a great height-50 or 100 or 500 mileswhich the sunlight effects the separation but the utmost intensity of the sun's rays of the oxygen, and the point between at descends through it without any effect of which the effect is at a maximum. heat or warmth, and there shuts down
“The evolution of oxygen,” he says, forever upon the lower range of our at“begins in the blue light, ascends through mosphere an inconceivable terror of cold the green of the spectrum up to the mid- accompanied beyond, through the imdle of the yellow, and there reaching its mensities of space, with a limitless blackhighest point, again descends in the ness of eternal night. orange-colored rays, to cease within the red portion of the spectrum."
AIR LIFE-SUSTAINING ONLY NEAR THE And again he says:
EARTH "The decomposition of carbon dioxide in And we may note here, without any the plant evidently depends upon a photo special inquiry as yet into the part played chemical effect. Draper found that the by the oxygen of our atmosphere as the effect in the red portion is extremely fee- universal breath of life to all living things, ble, rising quickly in the red-orange, and that the sea of oxygen gas, mingled with reaching a maximum in the yellow-green, a four-fold amount of nitrogen gas, which to fall again in the blue to an extremely forms nearly the whole mass of our atmossmall quantity. It is the yellow light phere, does not extend in life-sustaining which is the effective constituent of day- amount and strength more than about light in the nutrition of the plant; all seven miles from the surface of the direct observations show that the maxi
earth. mum evolution of oxygen takes place in Even high among the mountains of a yellow light.”
country like Switzerland, the mass of This evidence as to the relation of oxy. oxygen in the air available for our breathgen to the spectrum is in harmony with ing has become so much rarer than at the other proofs going to show that oxygen, ordinary level as to necessitate a more by its range of vibrations, determines vigorous effort of breathing, in order, by within what limits “the electrical organ” greater exertion, to get an adequate which Hertz calls the eye, can receive amount of oxygen into the system; and, from solar vibrations the effect of light. as the balloon rises into space, the diffiThe eye is tuned by the vibrations of the culty of an adequate oxygen supply inoxygen of respiration.
creases, until, at six or seven miles from The sun sends a range of vibrations, the bottom of the sea of air, there is not into a particular part of which falls the enough to make sure of motion in the range of oxygen vibrations, and within limbs, energy in the brain, or even a this part only do solar vibrations give the flickering vitality in the body. effect of light to our eyes. And that The account in the Encyclopædia Brit
annica article,“Aeronautics,''* of a mem- stand as electrically caused. Heat is no orable ascent to a height of seven miles, less of purely electrical origin. Lord or 39,000 feet, by Messrs. Glaisher and Kelvin, in a Royal Institution lecture on Coxwell, shows in the most striking “The Origin of Motive Power,'' has said: manner how the failure of the oxygen “In a series of admirable researches supply at that height stops all power of on the agency of electricity in transformamovement in the various parts of the tions of energy, Joule showed that the body, one after the other, as they fail to chemical combinations taking place in a get oxygen, and finally suspends all con- galvanic battery may be directed to proscious sensibility, and leaves no possibil duce a large, probably in some forms of ity, in the intense cold of that elevation, battery an unlimited, proportion of their but of speedy death.
heat; not in the locality of combination,
but in a metallic wire at any distance INCALCULABLE ELECTRICAL EFFECTS, from that locality.* Thus, if we allow THROUGH THE AIR, OF THE zinc to combine with oxygent by the SUN'S RAYS
beautiful process which Grove has given
in his battery, we find developed in a wire But when we have thus brought with connecting the two poles the heat which in the limit of environing facts our view would have appeared directly if the zinc of the atmosphere, as for all purposes of had been burned in oxygen gas.” advantage to life on the earth, an envel- Faraday estimated that so minute a ope of gaseous substances but a few portion of water as 2574 grains-about miles in depth (or in height above our 25 drops—has its atoms of oxygen and heads), it cannot be too distinctly recog- hydrogen locked together by a quantity nized that almost incalculable effects reach of electricity, and requiring another equal us at the bottom of the atmospheric sea amount of electricity to shake them apart from the sun's immensity and activity. into gases, the current effects of which Distant as the sun is, and immense as are would keep any length of platina wire of the spaces of eternal cold and night Idy of an inch diameter red hot for an through which his influences must travel, hour and a half; and Wheatstone estithe overwhelming storms of solar energy mated that these current effects would playing about mountains 300 miles high, appear in one second at a distance of rolling thousands of miles in depth over 576,000 miles. The quantity of power the surface of the solar orb, and thrust connected with the excitement of so small ing tongues of lightning a hundred thou- an amount of water, to shake its atoms sand miles into space, easily and instantly apart and permit the formation of moletransmit to the receptive constituents of cules of the two component gases, Faraour atmosphere a variety and an aggre- day said equalled that of “a most degate of effects, our uninstructed observa- structive thunder-storm.". tion of which suggests a very near and In the combination, Faraday tells us, close connection between sun and earth and a path of the solar power flooded all *Joule's memorial papers were : the way with heat and light.
« On the Production of Heat by Voltaic ElecThe fact is that to the purely electrical he purely electrical tricity'; Roy. Soc. Proc., Dec. 17, 1840:
“On the Heat Evolved by Metallic Conducemanations which are the cause of both
tors of Electricity, and in the Cells of a Batlight and heat from the sun, no aids on tery during Electrolysis”; Oct., 1841: the path are needed; nothing but the “On the Electrical Origin of the Heat of changeless continuity of the ether of uni
Combustion”; Mar., 1843:
"On the Heat Evolved during the Electrolyversal space, and those effects which are
sis of Water"; 1843: brightness and warmth to us are the re "On the Calorific Effects of Magneto-Elecsponse of mundane and atmospheric con tricity.” ditions to the electric thrills from the sun. Chemical expression is made deplorably inLight we have come to very fully under
accurate under the entirely false and misleading conception of "attraction. There is no action
of theʻzinc combining with oxygen. The action *The account is quoted elsewhere, as evi. is that of the oxygen dashing upon and condence in regard to the instant and absolute de- suming the zinc. The dash of the oxygen pendence of life, not upon chemical action in throws off electricity; in the battery or in our the body, but upon the constant inrush of the fires; and the heat caused is from this thrownoxygen of respiration, with an immediately off electricity, not from that which operates physical animating and vitalizing effect.
of oxygen and hydrogen to form water, filled the capacities of all moving and livelectric powers to a most enormous ing things. amount are for the time active, but no How the sun rules the kingdoms of naexamination which we can make of the ture and of life through the effects which flame which they form during their ener- it operates in the realm of atmospheric getic clashing together shows us any conditions under which these kingdoms signs of what is going on, save those lie, has been very imperfectly comprewhich are purely incidental, and are in- hended and very inadequately or erronecomparably small in relation to the forces ously explained; but the great fact is concerned.
rightly making a stronger and stronger It is in the same unnoticed way that impression with every fresh enlargement electrical energy, beyond all imaginable of knowledge, and no possible hope of limit in amount, may be operative be- better science can be cherished than that tween the sun and the earth, emanating of a complete comprehension of the part from the vastness and the intensity of the played by the enveloping atmosphere of solar fire-ball, and acting through the our planet for everything that moves and mass of our atmosphere as unobserved as lives upon it. the lines of force of the magnet. No principle lies deeper in nature than that DIFFERENT RELATION ro THE SUN OF of the likeness of the kingdom of force THE TWO HEMISPHERES OF THE to the kingdom of spirit, in that it com
EARTH. eth not with observation, does not submit itself to our inspection for anything more Owing to the eccentricity of the earth's than relatively unimportant incidentals, orbit, it travels around the sun at a varyand has to be comprehended by imagina ing rate through the different periods of tion and faith. Tyndall saw this when the year, and is at a varying distance he said:
from the sun. About ten days after mid“The ultimate problem of physics is winter of the northern hemisphere, the to reduce matter, by analysis, to its lowest earth is at her nearest to the sun. An conditions of divisibility; and force, to its important difference is thus established simplest manifestations; and then, by syn between the seasons of the two hemisthesis, to construct from these elements pheres. In the northern we have the sun the world as it stands. We are still a farthest from us a few days after midlong way from the final solution of this summer, while at the corresponding seaproblem; and when the solution comes, son in winter the sun is at his nearest. it will be one more of spiritual insight So far, then, as the sun's distance is conthan of actual observation."
cerned, the seasons are rendered more Tyndall was too far from a clear con moderate for the northern hemisphere by ception of the problem to state it accu- the effects of the earth's eccentricity. rately; Faraday saw more clearly when Nor is the difference on this account by he doubted the good of chasing atoms any means inconsiderable. The earth rethrough the possibilities of divisibility, ceives about one-fifteenth more heat in and conceived that of what are called aphelion than in perihelion. And in atoms we need rather to know what winter the earth moves more rapidly moving agency attends them, handles than in summer, so that the interval from them, and gives them their place, of action the autumnal to the vernal equinox is or of hold-fast combination; but it was shorter than that from the vernal to the truly and well said that at the bounds of autumnal. Thus, for us, the winter cold actual observation thought passes on is less enduring than the summer heat. alone to penetrate the realm of final facts. In the southern hemisphere all these
Of that realm, the gates ajar of pro- relations are reversed. The summer heat foundest insight not only permit, but com- is rendered more intense by the greater mand the utmost endeavor of imagination proximity of the sun, and the winter cold and effort of faith to follow electric agency is intensified by his increased distance. in the whole making and maintenance of The summer heat, also, is less endurthe cosmos of order and power, in sun or ing than the winter cold. We have in star or earth; and nowhere more than in the north a relatively short, but moderthe vast urns of our atmosphere and the ate winter, so far as the sun's proximity vast fountains of the sun, from which are can moderate winter cold, and a long, but also moderate summer. In the The direct rays of the sun would be hotsouthern hemisphere they have a short ter in falling, only to be followed by inand intensely hot summer, and a long tense cold after their withdrawal. In and intense winter. The presence of a order to have any continuous elevation great expanse of sea in the southern hem- of temperature, an atmosphere must supisphere partially tends to moderate the ply some means of absorbing heat, and seasonal changes; but we see in the wider of throwing back the radiation, upward, of extension of the antarctic snows the effect heat from the surface of the earth. of the long and the cold winter and the Aqueous vapor in the air is a most effectshort summer. *
ive means, because of its exceptional
power to absord the heat effects, and to HEAT EFFECTS OF THE SUN DEPEND radiate them back to the earth. ON CHARACTER OF THE AIR.
“Weight for weight," says Tyndall,
“aqueous vapor transcends all others in The possible effect of an atmosphere in absorptive power. The power of the confining beneath it the heat effects water molecule as a radiant and an abwhich have reached the surface of the sorbent is perfectly unprecedented and earth, may be illustrated by what Tyndall anomalous. That ten per cent. of the says of a gas the power of which to stop entire terrestrial radiation is absorbed by the upward radiation of heat is extremely the aqueous vapor which exists within great. Tyndall's statement is this: ten feet of the earth's surface on a day
“Were our globe encircled by a shell of average humidity, is a moderate estiof olefiant gas two inches in thickness, mate. The aqueous vapor exercises a the shell would offer a scarcely sensible powerful absorption on the invisible obstacle to the passage of the solar rays calorific rays of the sun, which experiearthward, but it would intercept, and in ment shows to be about twice the visible.” great part return, 33 per cent of the ter It was in view of facts such as these restrial radiation. Under such a canopy, that Tyndall, speaking of the effect of trifling as it may appear, the surface of our atmosphere on solar and terrestrial the earth would be kept at a stifling tem heat, said: “It is exceedingly probable perature. The possible influence of an that the absorption of the solar rays by atmospheric envelope on the temperature the atmosphere is mainly due to the waof a planet is here most forcibly illus- tery vapor contained in the air. The trated.”
vast difference between the temperature Neither the nitrogen nor the oxygen of of the sun at midday and in the evening the atmosphere would have any such [i. e. early evening, before sundown), is effect. It is to aqueous vapor in the air also probably due, in the main, to that that all such effect is due. Tyndall says: comparatively shallow stratum of aque
“Our atmosphere produces a local ous vapor which lies close to the earth. heightening of the temperature at the At noon the depth of it pierced by the earth's surface. The chief intercepting sunbeams is very small; in the evening substance is the aqueous vapor of the at- very great in comparison. The intense mosphere, the oxygen and nitrogen of heat of the sun's direct rays on high which the great mass of the atmosphere mountains is due to the comparative abis composed being sensibly transparent to sence of aqueous vapor at those great the calorific rays. Were the atmosphere elevations. But this vapor, which exer cleansed of its vapor the temperature of cises such a destructive action on the space would be directly open to us.” obscure rays, is comparatively transparent
to the rays of light. Hence the differAQUEOUS VAPOR IN THE AIR CONTROLS
ential action of the heat coming from the
sun to the earth, and that radiated from TEMPERATURE.
the earth into space, is vastly augmented This means that without aqueous va
by the aqueous vapor of the atmosphere. por in the air the heat effects which reach
De Saussure, Fourier, M. Pouillet, and the earth would be so thrown back into
Mr. Hopkins regard this interception of
the terrestrial rays as exercising a most space, except at the moment, as to give
important influence on climate. Now if, no continuous elevation of temperature.
as experiments indicate, the chief influ*E. B., Vol. II. 795.
ence be exercised by the aqueous vapor,