THIRTY-ONE POUND HOES

IF the boy on the farm had to wield for a few days a hoe weighing thirtyone pounds, he would probably consider hoeing the garden with a two-pound American hoe in the nature of a pleasure. The Kafirs of Africa use clumsy implements of great weight for hoeing corn. They even disdain to use the lightweight English or American hoes which the South African farmers have tried to introduce among them. It is needless to say that very little effective hoeing is accomplished in a day by these dusky natives of the Dark Continent.

It is also needless to say that the year's yield of corn suffers accordingly.

HORSE WRECKS TRAIN

AN unusual accident recently wrecked

a train, known as the finest operating in Oklahoma. While traveling sixtyfive miles an hour the flyer struck a horse and threw it against a switch stand, thus turning stand, thus turning the switch and wrecking the train.

Four coaches were converted intc kindling wood, and forty-eight people were injured-one death resulting.

A quarter of a million dollars represents the railroad company's lossfigures which will probably be largely increased by damage suits.

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The

HE run from Dover to Calais -the shortest water route from England to France-is just about twenty-two miles, but, even so, the misery that can be crowded into that comparatively brief trip fairly beggars description at times. A submarine tunnel from England to France would completely alter all these conditions. This idea in itself is not novel, but the fact remains that, while started years ago, an underwater route has never been completed. reason for this was that the English feared a military invasion, and they pictured themselves being pushed irresistibly toward the Irish Sea before the relentless bayonets of the French or the even more dreaded German soldiers. Mark you, these ferocious warriors were to come like an army of ants from underground and by way of the subaqueous tunnel which was to bind the British Islands closer to the Continent; and England's sagest military experts could conceive of no way of effectually blocking the tunnel against this imagined horde. This sounds funny, doesn't it? But these are the cold facts.

From time to time since, the project has been discussed anew, but as recently as six years ago it was vetoed because of the imagined military danger a completed tunnel might constitute. But now, England realizes that a far greater peril menaces from the sky in the shape of fleets of bomb-dropping dirigible airships, and still the foe most dreaded is Germany. The Channel Tunnel no longer looms up in its former appalling light, and sanity and commercial advantages are having their day of consideration. Accordingly, we are prepared for the announcement that a movement is on foot to link France and England by an

underwater tunnel capable of handling all of the passenger traffic and a large share of the more valuable freight. The point debated is whether it would be cheaper to complete the tunnel already started-representing an outlay of millions or to construct along an entirely new line. To Americans, interest in the undertaking should be aroused by the fact that one of our own countrymen has drawn up and submitted to the English authorities plans for an underwater tunnel of a novel character. Mr. Simon Lake, who is best known because of his work in the development of submarine torpedo boats, is the man in question.

In driving the borings for the tunnel back in the eighties-even though these extended but a short distance beneath the Strait of Dover-on several occasions crevices in the supposedly solid grey chalk were encountered through which for a while a disturbing amount of water entered the excavation. Fortunately, the overlying sit followed and automatically plugged the cracks. before the shaft was flooded. However, this was disquieting, and even today there is no certainty that worse conditions might not be encountered. Therefore, any scheme that would avoid this peril and which would not make it necessary to dig too far below the Channel surface, would have its advantages, provided a tunnel so built were otherwise secure. Here is where Mr. Lake claims that his system is far superior to others and, at the same time, can be built more rapidly and more cheaply.

What he proposes is a double tunnel planted in a broad trench dug in the bed of the Channel or the bottom of the Strait of Dover, as the authorities may elect. This subaqueous ditch would be just deep enough to allow the two traffic

tubes to sink below the level of the water floor, and over these tubes he would spread the rock-like chalk dug away for their reception. This chalk can be cut very easily, and the upper stratum being largely saturated can be dealt with pretty nearly as easily as some kinds of cheese. Mr. Lake has devised a special dredge which would be able to clear

is. Each tunnel section, or structural unit, will be from four to five hundred feet long, and the groundwork of each cylindrical link will be of sturdy steel. Inside it will be lined with cement and outside it will be similarly coated-thus shielding the metal work from attack. Before launching, each of these sections will be substantially complete-having

away the necessary trench at a rapid rate, and this is one of the numerous contrivances which he has planned for this and other allied submarine engineering undertakings. But you will probably ask, "How about the tunnel itself? In what manner is he going to build his tubes down there in the water a hundred and more feet beneath the surface and right upon the bottom exposed to the sweep of the strong tidal drift?"

Mr. Lake does not propose to construct his tunnel under water. He would build it on shore and plant the entire affair section by section after it had been fashioned on land and thoroughly tested before being sunk in place. Possibly this strikes you as being too radical to be practicable, but wait a moment and you will see how simple the fundamental idea

the rails in place and other operative fittings attached. But, temporarily, the open ends will be sealed by stiff bulkheads of steel set in place a short way in from the ends. Rising from the roof of the tube will be a chimneylike detachable shaft, and through this, workmen can later on pass up and down and ventilation can be established with the free atmosphere.

The tunnel unit, on being launched, is towed to its intended position and anchored. Then water ballast is let into it until it is just heavy enough to sink and rest lightly in the trench. It is then moved so that its adjacent end either fits into, or over, the neighboring end of the section previously planted. When this contact is accomplished, the operatives in the other tube start the pumps and drain

The

the water away from between the nearby bulkheads. This produces an air pocket, or partial vacuum, against which the enveloping sea shoves the newly-laid unit, in this manner effectually sealing the joint which is later made permanently secure by bolts and nuts. next thing is to pile the broken stone or chalk over the new section in order to anchor it in the trench for all time. When this is done, the water ballast is pumped out and the workmen go down. through the roof shaft to complete their tasks within. The adjoining bulkheads are removed, only the end one farthest away is left in place. The air shaft and workmen's passageway is removed finally in this fashion: a door, or heavy plate, is dropped into the opening on the roof of the tunnel and sealed by cement -the shaft is detached after a door in its bottom has been closed. The shaft can also be removed, after the hatchway into the tube has been sealed by a diver. But Mr. Lake's principal aim is to limit as far as possible the employment of workers of this sort because of their expense and the risks they run and the short periods they are able to perform effective service.

The planting and the attaching of succeeding tunnel sections are similar to the processes already described, and the work can be pushed along just as fast as the

units can be built, equipped, tested, and launched. Nothing is left to speculation, or guesswork-every part of every section can be examined thoroughly before it is put into the water, and this supervision and foresight are the best guarantees against delays and disaster. Somewhat 'similar work was done in Paris when tubes for the Underground were built on land and sunk in the bed of the river Seine, and the manner in which the Detroit River Tunnel was laid is another evidence of the advantages of this system. But in the .case of the Channel Tunnel, Mr. Lake is virtually dealing with the open sea, and therefore he has difficulties of an unusual nature to meet. However, he believes he has the means of overcoming successfully each and all of them.

There are a number of engineering advantages inherent in tunnel laying in trenches dug in the bed of a river or any other body of water, all of which make for economy and quickness of building, but there is one which even the layman may appreciate. Tunnels dug below the waterbed, as most of them are, are so deep that the land approaches must either be at very sharp angles or they must reach shoreward for long distances. A system like Mr. Lake's shortens the land ends, because the rise to the surface can be made more quickly.

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VERYONE is familiar with the bar of light with its ghastly greenish illumination used in power houses and in factories where the employes would submit to its use. This "mercury vapor lamp", as it is called, has gradually spread all over the United States because of its great economy, and in spite of the disagreeable greenish tinge that it gives to everything illuminated by its light. Scientists have written pages and pages to prove that the green light is beneficial to the eyes; economists have expounded upon its saving in electric light bills; civic councils and factory owners have endeavored to introduce it; but the people would have none of it! That ghastly greenish glare was simply too much-it made your neighbor look as if he had died several weeks before, and the appearance of your own hands assured you that you

LAMP

had jaundice in its most virulent form! This light is produced by vaporizing mercury in a long glass tube by means of a powerful electric current. There are no red rays in this light, because vapor of mercury gives out only yellow, green, and blue rays and so can never show in the natural colors anything it illuminates. To the average man it would seem easy enough to put red rays into the light by making the tube of red glass, but the actual effect of such an experiment was to eclipse the light entirely. The reason is, of course, that red glass will pass nothing but red rays, and, the incandescent mercury vapor having none, no light is forthcoming.

Another attempt to eliminate the objectionable green tinge was the experiment of increasing the intensity of the current or decreasing the length of the tube. The mercury vapor then