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��Popular Science Monthfy
��the salts on top by passing up through the porous substance from the magne- sium chlorid below. In this way a good sliding surface is maintained.
��Limbering the Muscles of Fire-Fighters
THAT the fireman's life is not all velvet was proved in New Or- leans recently, when the fire depart- ment turned out in force and did some remarkable feats of quick lad- der-climbing for the edification of the public. A tall wooden tower was erected, ladders were hoisted into position, and up these the firemen climbed in record-breaking time. The fire chief was so pleased with the demonstration that he ordered the tower to remain in its original position, to be used in the future for regular ladder-climbing exercise.
In New York, where there is a fire college connected with Central Head- quarters to which firemen from all parts of the world come to be enlightened in the latest methods of combating blazes, ladder-climbing forms one of the most rigid courses of training. All sizes of ladders are put up against the rear wall of the college and up these the "rookies" or probationary firemen are ordered by their superiors. At the topmost point of the highest ladder the rookies are sometimes sent with scaling ladders, which they attach to stone outcroppings or window sills and go up fifty or sixty feet further. This is the kind of training which instills a spirit of daring in the men. The training is made to resemble, as closely as possible, the problems in- volved in the actual work of fire-fighting.
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���One Reason for Appreciating the Value of Birds
THE fecundity of certain insect forms is astounding. The progeny of one little insect, the "hopaphis," sees thirteen generations born to it in a single year, and would, if unchecked to the end of the twelfth generation, multiply to the inconceivable number of ten sex- tillions of individuals. If this brood were marshaled in line, ten to the inch, it would extend to a point so sunk in the profundity of space that light from the head of the procession , traveling at the rate of one hundred and eighty-four thousand miles a sec- ond, would take two thousand five hundred >^ e a r s to reach the earth.
In eight years the progeny of one pair of gypsy moths could destroy all the foli- age in the United States, if un- checked.
���A demonstration of firemen's ability in ladder-climbing in New Orleans, La. These men proved so efficient in practical life-saving methods, that their chief ordered the tower to be left in position for the drilling of recruits
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