Page:Popular Science Monthly Volume 37.djvu/732

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THE POPULAR SCIENCE MONTHLY.

still more, thus assuring the doctor's presence oftener, and 168 in a million die. It is thus with every disease: the fewer it kills the more people fear it, because, if they did not fear it, they would play the fool, and give it a chance to kill more people. If bakers, grocers, dry-goods men, carpenters, tailors, and members of all other lines of business, gave as much of their labor in charity as doctors do, poverty would instantly be wiped from the earth."

 

Dragon-flies and Mosquitoes.—A study of practicable methods of getting rid of the nuisances of flies and mosquitoes has been set on foot by Mr. Robert H. Lamborn, of New York, aided by Mr. Morris K. Jessup; and the first fruits of the effort will shortly appear in the publication of three essays, for which prizes have been awarded. Mr. Lamborn, having been struck with the voracity of dragon-flies, and their activity in destroying mosquitoes and flies, invited attention to the investigation of their life history, and of the possibility of propagating them and applying them directly to the destruction of the noxious insects. The investigations showed that under natural conditions dragon-flies were among the most formidable enemies that the offensive insects had to encounter; but the results as to the practicability of artificial propagation and application were not encouraging. Mrs. Aaron, of Philadelphia, to whom the first prize was awarded, found that, as they do not breed in the same waters as the mosquito, they would have to be produced on an enormous scale and then taken to the mosquitoes; and that the artificial breeding of them is attended with great difficulties. Mr. Archibald C. Weeks, of Brooklyn, made experiments in breeding them artificially, and failed. They can not, moreover, be kept in houses and cities without changing their habits. Mr. William Beutenmuller, of the American Museum of Natural History, finds that dragon-flies are the natural enemy of the mosquito in its various forms and of flies, and that those insects disappear before them, but concedes the difficulty of raising them artificially. These experiments do not dispose of the question of our calling dragonflies into service. Early efforts usually fail of the success that follows patient persistence. Much may be accomplished at once by encouraging the natural multiplication of the Libellulidæ; and future effort may yet develop a practicable way of raising them artificially. Other remedies are suggested which seem efficient and more immediately practicable. Among them are the cultivation of the yeast-fungus, which is fatal to flies, and attacks them frequently; fish-planting; thorough draining of spots where water can stand; and insecticides, one of the most efficient of which is kerosene. One drop of oil applied to a pool having ten square inches of surface cleared it very quickly of all life; and three dollars' worth of crude oil will be sufficient to apply to a mosquito-pond of a hundred acres five times in a season. Spraying petroleum on compost-heaps and other breeding-places is equally effective to prevent the development of flies.

 

Walking-Sticks and Umbrella-Handles.—The art of making walking-sticks and umbrella-handles has been greatly developed during the last forty years. Formerly, only a very few native woods and some foreign species were used for these purposes. Twenty years ago the first collection illustrating the materials used was presented by a London firm to the museum at Kew. The collection has been completed by a supplementary one from the same house, and in its later form exemplifies many points in the advance of the art. There is now hardly any limit to the material that can be turned to account for the purposes under consideration, and manufacturers keep a keen lookout for new sources of material, and novelties in sticks and fashion. The cultivation of sticks for the market has been taken up as a business at some places in continental Europe, and special attention is often paid to making the roots grow into shapely forms for the handles. A London manufacturing establishment, the floor space of which nearly covers an acre, have extensive storehouses filled with native and foreign sticks, from which stock is drawn, as it is wanted, for the shops. These, as they grow, are often very crooked, and have to be straightened. A heap of sand is provided on the top of a very hot stove, into which the sticks are plunged, and kept till they have become pliable. "The workman then takes