Ashbury College - Ashburian Yearbook (Ottawa, Ontario Canada)

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THE ASHBURIAN Il9j I let the refracted light fall 1merpendicularly upon a sheet of white paper. and observed that the image on the paper was coloured, being red at its least refracted end, violet at its most refracted, and yellow, green and blue in the in- termediate spaces. Newton had split up the beam of white light into the familiar colours of the rainbow. Newton followed up this experiment with many others which left him in no doubt of its message. Light must be the blending of those coloured rays. At once the realization of this truth gave a fresh interpretation and under- standing of many phenomena. The mystery of colour, for instance, was nearly solved. Thus everybody is now aware that a geranium is not really red any more than eyes that appear blue are blue. XYhat happens is that when sunlight falls on the geranium the substance of the flower miraculously absorbes all the white light save the red which it reflects. If, therefore. a green light were directed on it the bloom would appear black as nothing is reflected. Grass is green be- cause the grass cannot absorb the green light so it is reflected. The discovery, by Newton. of the Spectrum, as the group of colours com- prising white light is called, laid the foundation of the study of Radiation. How did those rays of light travel? That was the next question. Newton thought that a stream of particles of light travelled to ,us from the sun in straight lines. But he was mistaken. His theory certainly fitted some of the phenomena of light such as reflection, but it did not allow for the fact that a beam of light bends round a corner and illuminates on the other side a body placed in its path. This bending is known as diffraction. But what caused those differently coloured rays of the Spectrum? XX'hy should one be green and another blue. By infinite labour and thought the mystery was solved. It was found that different colours were produced by different wave-lengths, that the waves of green light, for instance. were longer than those of blue light and that those of red light were longer again than those of green. That then was the beginning, the very first division in the great scale of waves. Red, orange. yellow, green, blue. indigo and violet-seven different colours were produced by seven different wave lengths. Now these waves must travel in something. But the light from the sun reaches us across a 93.000000 mile gulf which apparently is airless. empty space. Since waves, however, cannot exist in nothing, scientists have put forward the theory that space, far from being empty, is filled completely with something which they have named Ether,

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l181 THE ASHBURIAN THE WONDERS OF RADIATION By VV. A. GRANT T IS quite true to say that there is nothing of such vital importance to us as Radiation, and nothing which fills the mind with more awe. Wiithout it there would be no wireless, no electric light, no gas light. no sun- light. There would be nothing growing upon the earth, for there would be no heat from the sun, and therefore if Radiation ceased human life would also cease. On Radiation, then, our very lives depend. Ile have not yet lost that sense of the miraculous with which the advent of wireless filled our minds. Ile still say How wonderfulw, when we think of those wireless waves coming to our sets across a thousand miles of space. un- checked by forest, mountain or ocean. IYonderful as that is, indeed, our wonder- ment is increased when we realize that radio waves form but a very small section of an immense range of waves which fill the limitless space around us and produce such widely different phenomena as sound, light, heat and electricity. All these waves are closely related and belong to one gr-eat system, one great scale in which each kind of wave has its allotted position, that position being decided by a certain characteristic of the wave. So closely related, in fact, are all these waves that they may be regarded as one great family, the members of which differ from one another in certain particulars, such as energy, but yet bear the essential family likeness. lYhen recently Professor Picard, with his assistant, risked his life by ascend- ing over ten miles into the upper air. he was engaged in research of the Cosmic- ray. a brother of the X-ray, of electricity. of light. A clear picture of this huge family of waves will be obtained by considering its numerous forms, for the story of these waves, their strange qualities. their immense power, and man's indomitable perseverance and ingenuity in discover- ing and then harnessing them to his purpose, is indeed a romance. Let us consider first visible light waves. remembering that they occupy onlv one division of the seventy odd that make up the universal scale. Une day in 1675 Sir Isaac Newton took with him into his dark-room a prism of glass. Could the far reaching results of his experiment have been foreseen, the linking up of continents by radio, the healing of human ills by radio-theraphy, none would have been more surprised than he. In a very dark chamber , he tells us, at a round hole about a third of an inch broad, made in the shutter of a window, I placed a glass prism, whereby the beam of the sun's light which came in by the hole might be turned towards the opposite wall of the chamber.

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moi THE ASHBURIAN Of this lither nobody in the world knows its exact nature, but it is thought to be of an immense density, and for this reason. Sound travels quicker in water than in air and quicker still in metals. So, it may well be agreed that the speed of waves depends on the density of the medium through which they pass. Now the speed of light is almost instantaneous and therefore the density of the ether must be almost infinite. Any article on Radiation would be incomplete without mention being made of the wonders of the X-ray, certain of which carry sufficient energy to penetrate two inches of lead. There are the soft X-rays, less penetrative than the others. such as are used in the shoestores for a correct Fitting, and the hard X-rays, used for medical purposes. But there remained yet another division in Radiation. that of the Cosmic rays explored by Professor Picard in recent times. The penetrating power of these rays can be imagined when it is realized that they are capable of penetrat- ing several yards of lead and have been detected under 800 ft. of water. They were first discovered in the early part of the twentieth century by McLellan and Rutherford and subsequent investigations showed that the amount of cosmic Radiation was independant of the earth's position. Neither day nor night nor the seasons of the year effect the energy received from this source. Evidently they cannot originate in the sun for if this was the case they would be interrupted by the earth's rotation and thus it was concluded that they started from somewhere outside our system. The effect of Cosmic rays on life generally and human life in particular has not yet been fully determined, but Sir .lames .leans asserts that every second Cosmic radiation disintegrates millions of molecules in our bodies. Every second also it is breaking up twenty molecules in each cubic inch of air. So much for the Cosmic-ray, Now let us consider briefly the question of the speed of light. a question inextricably bound up with Radiation. Light travels at the rate of 136,000 miles a second. lf we could travel on a beam of light from our earth we should reach the moon in lk seconds, the sun in 81,5 minutes and Proima Centauri, the nearest star. in four vears. If there were inhabitants on a planet in the Hercules Cluster, and their astronomers directed a super-telescope upon our earth, they would at this hour see something of our life in the Neolithic Age. XYhy is this you may ask. The answer is that the Hercules Cluster is 36,000 light years distant from the earth. That is light travelling at 136.000 miles a second would take 36.000 years to reach that Cluster.