upon the earth from the distant sun. That light really does sway infinitely small particles was first experimentally proved by the Russian Lebedev. Two Americans, Nichols and Hull, improved upon his method. They cast the solar effulgence into mighty mathematical scales and found that the earth sustains a light load of no less than 75,000 tons. It remained for the broad mind of a Swedish physicist, Svante Arrhenius, to apply the principle of light pressure cosmically, and to explain, 1874 NEPTUNE 1895 URANUS 1903 SATURN 1908 JUPITER 1910 THE ORBIT OF HALLEY'S COMET, WHICH IT PASSES OVER IN 75 TO 77 YEARS easily be driven away from the sun by radiation pressure. To understand how it is possible for so immaterial a thing as a sunbeam to produce so huge an effect, we have only to take a very simple example. Assume that you have before you a block of wood weighing one pound. The block exposes a certain amount of surface to the sun's light. Saw the block in half, and you increase the amount of that surface. Divide each half again into half, and the exposed surface is further augmented. If this process of subdivision is carried on far enough, the block will be reduced to sawdust. The entire mass of sawdust still weighs one pound; but its surface has been vastly enlarged. Indeed, the particles of sawdust, individually considered, may be said to consist of much surface and very little weight. If it were possible to take each granule of visible sawdust and subdivide it into invisible particles, a point would be reached where the pressure of light would exactly counterbalance the pull of gravitation, so that the particles would remain suspended in space, perfectly balanced in the scale of opposing cosmic forces. Finally, if the subdivision be continued beyond this critical point, the particles will be wrenched away from the gripof gravitation and hurled out into space by the pressure of light. So much has been discovered about the particles that compose a comet's tail that the more pro gressive scientists of our day have accepted this ingenious theory. It has been discovered, for example, that the delicate tresses of a comet are to a large extent composed of fine particles of dust and soot. Before we can completely accept the view that light pressure forms this train of soot we must ascertain whether the pressure of light is capable of accounting for the flash-like rapidity with which a comet's tail changes. A comet may throw out a tail sixty million miles long in two days. Is it actually possible for light pressure to accomplish that astonishing feat? Arrhenius has computed that 865,000 miles an hour is the speed of a light-flung particle of one-half the critical diameter. Because they are only oneeighteenth as large as this particle of critical diameter, cometary dust grains would be propelled over the same 865,000 miles in less than four minutes. It follows that the solar radiation would experience no difficulty in tossing out a tail of sixty million miles in two days. FOREWORD Hartford, the capital of the State of Connecticut, is one of the most prosperous and beautiful cities in New England-and New England is not uncommonly nor unreasonably supposed to be the most enlightened section of the United States. The figures of the last census gave the city a population of eighty thousand inhabitants, and its unusual wealth is indicated by the single fact that the total assets of the fire and life insurance companies which have their head offices in Hartford and are the creation of Hartford capital and skill amount to one hundred and seventy-five millions of dollars.. Hartford is the seat of Trinity College and one of the chief theological seminaries of the Congregational Church; moreover, its public school system is an admirable one, and it spends annually on these schools a sum amounting to between three and four hundred thousand dollars. Thomas Hooker, the famous clergyman and statesman of colonial times, a graduate of Emmanuel College, Cambridge, England, in 1608, was a citizen of Hartford, and is by some historians called the father of American democracy, which gives Hartford an excellent claim to the title of being the birthplace of that democracy. If, with all these historical, social, and material advantages, such conditions can prevail among the newsboys and newsgirls of Hartford as are portrayed in the accompanying illustrations from life, no argument needs to be stated to prove the need of such an organization as the National Child Labor Committee, in the process of some of whose investigations the photographs were taken upon the streets of Hartford. Under the auspices of the State Consumers' League and the National Child Labor Committee, a bill was introduced last winter to remedy some of these conditions, but it was rejected by the State Senate. Our able contemporary the Survey points out the significant fact that on the same day that this bill was rejected the Connecticut Senate passed a bill providing that women and children may be employed in shops and department stores every night of the year until ten o'clock, and without any limit whatever as to hours of work in the week preceding Christmas. No doubt there are other cities where the conditions of newsboys and newsgirls are quite as bad as those prevailing in Hartford, but the retort of tu quoque will not serve to remove from Hartford the distinction of setting to-day a typical if not a flagrant example of American indifference to the welfare of children made day-laborers before their time.-THE EDITORS. |