Page:Popular Science Monthly Volume 43.djvu/148

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138
THE POPULAR SCIENCE MONTHLY.

Florists who do business in villages and towns enjoy opportunities for doing effective work among children by explaining to their young visitors the methods of propagation. The claims of children should never be forgotten in making up the lists of premiums for agricultural and horticultural fairs. Prizes should be given for plants grown by them and for bouquets and collections of wild flowers made by them. Village improvement societies are doing excellent work in many sections. Some have distributed seeds and plants to the school children with most satisfactory results.

 

African Pluck.—Mr. Alfred Coode Hore, in his Eleven Years in Central Africa, speaks well of the tribes of the Tanganyika region, which he finds are peaceable and industrious for the most part, but turbulent and aggressive when they have learned to dread molestation by strangers. "It seems hard," he says, "that a man should be called lazy because he has ample leisure between his busy times; who has made with his own hands from Nature's raw materials his house, his axe, hoe, and spear, his clothing and ornaments, his furniture and corn-mill, and all that he has, and who, though liable often in a lifetime to have to commence that whole process over again, has the energy and enterprise to do so. Too often have the same people been called savage and bloodthirsty who, through all experience and by all their traditions regarding armed strangers as enemies, defend themselves and their own with the desperate energy which, as displayed by our own ancestral relations, we term patriotism and courage."

 

Impurities in Ice.—The once popular theory that water is purified by freezing is, as Mr. Charles Platt shows in Science, not in accordance with facts. While water in its crystalline state should theoretically be nearly pure, still, owing to its formation in needle-like crystals, considerable foreign matter present in the water in suspension may be and is mechanically held within the mass. Another view, that in the freezing of still water a certain concentration of some species of bacteria on the surface of the water may take place, and the first inch of ice may contain these in increased numbers as compared with a sample of water from the same lake, may be well founded, but it is not yet proved that these bacteria have an increased or any vital activity. But when the ice is melted and the temperature of the water is considerably raised, "then we have another problem, that of possible decomposition and organic change in those organisms that may induce results equal to and exceeding those of the bacteria themselves." Disease has undoubtedly, Mr. Platt affirms, been produced by the use of ice from impure sources) and this, too, when mere analysis of the ice in comparison with water standards would not condemn it. But the standards in the analysis of ice must be higher than in that of water. The Massachusetts Board of Health has pointed out that it is not the number of bacteria alone that is to be considered, but their kind, and insists that no water supply that is not fit for drinking purposes should be used as a supply for ice. This is done when ice is gathered from stagnant ponds and sluggish canals that receive the drainage from various sources. Snow ice and ice that has been formed by flooding ice fields with surface water are very liable to be contaminated. In making artificial ice it is customary to use the entire contents of the water tanks. In that case the impurities, repelled at first by the ice forming at the sides of the vessels, are driven to the center and there concentrated, to be at last included in the freezing of the entire mass.

 

Protection of Orchards against Frost.—According to Charles Howard Shinn, in Garden and Forest, experiments are carried on on a practical scale for the protection of fruit against frost in the orange groves at Riverside, Cal. In some winters the temperature falls so low that the oranges are destroyed or injured. As a remedy the cultivators are using appliances for warming the orchards on a large scale. Their experiments show that the temperature can be raised from four to ten degrees by the use of fires. The moment the thermometer falls to the danger point electric bells can be rung and tanks of crude petroleum lighted. One man has fitted up an eighty-acre orchard at a cost of $10,000 or $12,000. He claims that his grove is absolutely protected, and that the running expense will be very little. Other