Yet Christian orthodoxy, which itself has, all but uniformly, understood this passage of the spiritual radiation throughout the world of the Word before His incarnation, has been aided towards such breadth as to the past by the Johannine outlook into the future.
If heat passes "of itself" from a higher to a lower temperature by conduction, convection or radiation, the transfer cannot be reversed without an expenditure of work.
The most fundamental experimental confirmation that the theory of the aether has received on the optical side in recent years has been the verification of Maxwell's proposition that radiation exerts mechanical force on a material system, on which it falls, which may be represented in all cases as the resultant of pressures operating along the rays, and of intensity equal at each point of free space to the density of radiant energy.
Of Strassburg by rail, and at the radiation of lines to Luxemburg, Coblenz and Noveant, on the French frontier (102 m.
By thus controlling and partially eliminating the aggregate gas-effect, they succeeded in making a small radiometer, horizontally suspended, into a delicate and reliable measurer of the intensity of the radiation incident on it.
Poynting has separated the two effects experimentally on the principle that the radiometer pressure acts along the normal, while the radiation pressure acts along the ray which may be directed obliquely.
According to modern measurements the solar radiation imparts almost 3 grammecalories of energy per minute per square centimetre at the distance of the earth, which is about Iï¿½3 X io s ergs per sec. per cm.
In all cases of wave motion the wave-length is connected with the velocity of propagation of the radiation by the relation v=nX, where n is the frequency of the oscillations and X is the wave-length.
Again, the temperature of the air is affected by radiation from the soil; and radiation differs in various soils.
In the winter similar consequences ensue, in a negative direction, from the prolonged loss of heat by radiation in the long and clear nights - an effect which is intensified wherever the surface is covered with snow, or the air little charged with vapour.
With the experience thus gained in manipulating the vacuum, the achievement of thoroughly verifying the pressure of radiation on both opaque and transparent bodies, in accordance with Clerk Maxwell's formula, has been effected (Physical Review, 1901, and later papers) by E.
The above statements, though correct as far as they go, are an imperfect account of the nature of the radiation from a coupled antenna, but a mathematical treatment is required for a fuller explanation.
A problem of great importance in connexion with electric wave telegraphy is that of limiting the radiation to certain directions.
We have not the slightest reason to think that the radiation from the sun is measurably weaker now than it was a couple of thousand years ago, yet it can be shown that, if the sun were merely radiating heat as simply a hot body, then it would cool some degrees every year, and must have cooled many thousands of degrees within the time covered by historical records.
Among his articles may be mentioned those which he wrote for the ninth edition of this Encyclopaedia on Light, Mechanics, Quaternions, Radiation and Thermodynamics, besides the biographical notices of Hamilton and Clerk Maxwell.
He was distinguished as the discoverer of radioactivity, having found in 1896 that uranium at ordinary temperatures emits an invisible radiation which in many respects resembles Rntgen rays, and can affect a photographic plate after passing through thin plates of metal.
This reflection is suggested by the following articles: Aether; Molecule; Capillary Action; Diffusion; Radiation, Theory Of; and others.
This phenomenon he explained as a "repulsion from radiation," and he expressed his discovery in the statement that in a vessel exhausted of air a body tends to move away from another body hotter than itself.
Its foreshore consists of a great expanse of firm, bright sands, and the mildness of its winter climate is attributed to the radiation of heat from them.
The word actinometer is now usually applied to instruments for measuring the actinic or chemical effect of luminous rays; their action generally depends upon photochemical changes.
The warming of the ocean is due practically to solar radiation alone; such heat as may be received from the interior of the earth can only produce a small effect and is fairly uniformly distributed.
Great irregular variations in radiation and convection sometimes produce a remarkably abrupt change of temperature at a certain depth in calm water.
At sunset, too, after a warm day, if the air is still, the cooling of the earth by radiation cools the lower layers, and sound carries excellently over a level surface.
If we suppose that the aether differs from ordinary matter in degree but not in kind, we can obtain some idea of its quality from a knowledge of the velocity of radiation and of its possible intensity near the sun, in a manner applied long ago by Lord Kelvin (Trans.
If c is the velocity of radiation in free space and, u the refractive index of a transparent body, V= c/ï¿½; thus it is the expression c2 fï¿½ 2 (u'dx-}-v'dy+w'dz) that is to be integrable explicitly, where now (u',v',w') is what is added to V owing to the velocity (u,v,w) of the medium.
Hence the paths and times of passage of all rays relative to the material system will not be altered by a uniform motion of the system, provided the velocity of radiation relative to the system, in material of index ï¿½, is diminished by ï¿½ -2 times the velocity of the system in the direction of the radiation, that is, provided the absolute velocity of radiation is increased by 1-ï¿½2 times the velocity of the material system; this involves that the free aether for which, u is unity shall remain at rest.
Poynting may also be mentioned, in which the tangential component of the thrust of obliquely incident radiation is separately put in evidence, by the torsion produced in an arrangement which is not sensitive to the normal component or to the radiometer-pressure of the residual gas.
Taking into account the heat absorbed by the box and the metal, Rumford calculated that the heat developed was sufficient to raise 26.58 lb of water from the freezing to the boiling point, and in this calculation the heat lost by radiation and conduction was neglected.
The radiations interfere in an optical sense of the word, and in some directions reinforce each other and in other directions neutralize each other, so making the resultant radiation greater in some directions than others.
Bellini and Tosi, who have devised instruments, called radiogonimeters, for projecting radiation in required directions and locating the azimuth of a transmitting station.
It has been suggested, however, that a prolonged period of volcanic activity may reduce the air temperature to a marked degree by throwing large quantities of dust into the atmosphere: this will act by preventing the penetration of solar radiation.) During a period of prolonged glaciation water becomes withdrawn from the ocean, for rainfall goes to form solid ice-caps that accumulate upon polar and continental land areas.