7H 



THE POPULAR SCIENCE MONTHLY. 



still more, thus assuring the doctor's pres- 

 ence 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 instant- 

 ly 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 vo- 

 racity of dragon-flies, and their activity in 

 destroying mosquitoes and flies, invited at- 

 tention to the investigation of their life his- 

 tory, and of the possibility of propagating 

 them and applying them directly to the 

 destruction of the noxious insects. The in- 

 vestigations showed that under natural con- 

 ditions 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 mos- 

 quito, 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 Beutenmuiler, 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 dragon- 

 flies into service. Early efforts usually fail of 

 the success that follows patient persistence. 



Much may be accomplished at once by en- 

 couraging the natural multiplication of the 

 Libellulidce ; and future effort may yet de- 

 velop a practicable way of raising them arti- 

 ficially. Other remedies are suggested which 

 seem efficient and more immediately practi- 

 cable. Among them are the cultivation of 

 the yeast-fungus, which is fatal to flies, and 

 attacks them frequently ; fish-planting ; thor- 

 ough 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 sur- 

 face 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. Spray- 

 ing petroleum on compost-heaps and other 

 breeding-places is equally effective to pre- 

 vent the development of flies. 



Walking-Sticks and Tmbrella-Handles. 



— The art of making walking-sticks and um- 

 brella-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 illus- 

 trating the materials used was presented by 

 a London firm to the museum at Kew. The 

 collection has been completed by a supple- 

 mentary 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 considera- 

 tion, and manufacturers keep a keen look- 

 out for new sources of material, and novel- 

 ties in sticks and fashion. The cultivation 

 of sticks for the market has been taken 

 up as a business at some places in conti- 

 nental Europe, and special attention is often 

 paid to making the roots grow into shapely 

 forms for the handles. A London manufact- 

 uring establishment, the floor space of which 

 nearly covers an acre, have extensive store- 

 houses 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 straight- 

 ened. 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 



