Strange Things About Light and Meat.

Golden Bay Argus, Volume 4, Issue 37, 8 February 1895, Page 2

Strange Things About Light and Meat.

By Bishop Clark. There are some things connected with the phenomena of light and beat to which the attention of the reader may never have ben directed. Light may exist without heat, as appears in the case of phosphoric substauc’s, which are self-luminous. Heat may abo exist without light, but only up to a ct - tain limit—all solid substances becoming luminous when heated as highas‘J77 degr- s, F dir- nheit. Gases require a much higher degree of heat before they become incandescent. No explanation has been found of the familiar fact, that, while both the light and heat, of the sun pa-s unimpeded through glass, artificial heat is intercepted by this transparent medium. It is a little strange that the heat of an ordinary fire'should pass freely through a layer of rock-salt, when it is unable to penetrate a pane of common glass ; and it is worth observing that while the hot rays of the sun pass through glass with such perfect freedom, they cannot find their way back by the same channel. The warmth o me inclosed in a hot-house, cannot escape by the process that allowed it to enter the building ; it must heat the glass panes in the roof ; ■is it would .uy other substance, in order to get out again. At first thought it is difficult to see why the rays of the sun should pass through the atmosphere without heating it at all; and yet, if it we.re not so, the temperature on the fop of Mount Blanc would be higher tha.i it is in the valley of Chamounix. But it is still more extraordinary that the rays of the sun should pass through a cake of ice without melting it at all, as is the ease when the thermometer staifds a little above zero. That the rays of heat actually penetrate the ice is shown by the fact that a lens of ice may r ( ne used for setting fire to inflammable sub- f stances. 1 f it were possible for us to rise above the itmosphere which surrounds the earth, we shonldsee nothing butan intense and sharplydefined bad of fire, whileevervthin; else would be wrapped in total darkness There could be no diffusion of light without an atmosphere, or some similar medium for it to acl upon ; but if the air about us extended to s height of 700 miles, the rays of the sun could not penetrate it, and we should be left in daik- • ness. At the depth of 700 feet in the ocean, the light ceases a! together, one-half of the light being absorbed in passing throughoulyseven feet of the purest water. I,i-ght its'-lf is colourless, and therefore, strictly speaking, it is never seen. The process by which it makes objects visible, when it falls upon them, is very interesting and wonderful, and yet it is a matter about which comparatively few persons ever concern themselves. Why is it that in a room in which everything was absolutely destitute of i colour so long as the shutters were closed, the 1 moment that the sunlight is introduced we 1 see such varieties of crimsons and greensand browns and yellows, elaborate patterns on the ■ walls and carpeted floors and draperies and ■ pictures of every shade and hue? “That is simple enough,” you may reply. “When the j room was dark, of course there was nothing i to be seen ; but as soon as it is light, everyj thing becomes visible, and each in its own 1 special colour.” But why is one thing red I and another blue? This red curtain had no \ redness about it when the room was dark it was absolutely without any colour at , all. i It had nothing more or less but a capacity \ for redness, and that capacity was deter- ; mined by the singular fact that when the ] pun’s ways fell upon the curtain it at once absorbed all but the red rays, and if- these were 1 excluded from entering-the room, while all . the other rays were allowed admittance, there | would not be a red thing to be seen. Why if ! is that, certain snbstatu.os absorb one set of colours and other substances another sort, nobody can tell.It seems to be a very commonplace thing to say that the fight makes objects visible by reflection ; but has the reader ever thought just what this implies? ' If it were possible to make a perfectly smooth surface, it would be invisible. But, as a matter of fact, nothing is perfectly smooth, and it is the little roughnes3er on the surface which break up the rays of light, and thus render the object visible to our senses. Wonderful deception! irv produced by the use of highly polished minors, with the most startling and magical effects. I Th- experiments of our modern photographers have revealed to us extraordinary chemical properties in the sun’s rays, while some of these rays are entirely destitute ol this peculiar power. It has also been dis- - covered that there are rays of fight outside oi the solar spectrum, and which are invisible to the human eye, just as there may be vibrations in the atmosphere too high or too low to produce an audible voice. , It is a mooted question whether the sunlight falling upon an ordinary wood-fire retards the process of combustion. This is a popular notion, and its certainly looks : as if the fire burned more feebly when the sun shines full upon it, and it is now alleged j by scientific men that there may be some such j influence produced by the action of the chemical rays. One would hardly have supposed that such subtle and volatile elements as light and electricity, after having been produced, could be stored away for future use ; and yet it is well known that a strip of paper, prepared after a certain fashion, and exposed for halt an hour to the rays of the sun, may be corked up and, if kept in the dark, retain its liiniinousness for a considerable period of time, The same property may be imparted to paint, and it has been proposed to apply this to practical uses. What a weird look one of oiu country villages would have ou a dark night if all the houses were painted with this phosphorescent pigment 1 The expansive and contractile power of heat and oold is one of the most irresistible 1 forces of nature. Bunker-Hill monument is ; 221 feet high, built of solid granite, and every day it oscillates to and fro, as the heat of the sun expands the eastern and western sides. If the iron rails on our roads were not allowed free play at the ends, they would : curl up like a snake. The tall and massive walls of stone buildings, when they have fallen away from the perpendicular, are righted j and restored to their proper position by.connecting them with metallic rods, which, after they have been expanded by heat, in the process of cooling draw the walls together with an irresistible force. We are all familial with the' application of the same principle in the hooping of oil-casks, and the tiring oi wheels. It is one of the anomalies of nature, that, while the cold contracts every other substance, water—although it also contracts up to a certain point—is actually expanded by freezing. This is one of the most striking indications of a wise and beneficent provision, as it is all that prevents our ponds and rivers from freezing solid to the bottom. Tc show the power of this expansive force, 3 would mention that a brass sphere, one fool in diameter, has been torn asunder by the expansion of a cubic inch of water, inclosed in the centre and then frozen. It is a familiar and yet it always strikes ns as a marvellous fact, that worlds may have been for years in existence, the light ol which has not yet had time to reach oui earth, and that we may still continue to see the light of stars that have been for a long time* extinct. What is to be the destiny of our world, after the sources of fight and heat are exhausted, as of necessity in process of time they must be? The earth may bo very old, but as it had a beginning, so it must, soonei or later, have an end. A group of men at a New York club not long ago were discussing actors, and a new arrival from England, who had been doing the theatres, said he did hot see much in Nat Goodwin. The talk went on, and Lady Archibald Campbell, the well-known aristocratic amateur, was named.’ “ Ah, there’s an actress, if you like," said the Englishman. “ Well,” said Howard Paul, who was one of the group, “that is what I call straining at a Nat and swallowing a Campbell.”