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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 for- 

 gotten hi 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 improve- 

 ment 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 aggres- 

 sive when they have learned to dread moles- 

 tation by strangers. " It seems hard," he 

 says, " that a man should be called lazy be- 

 cause 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 orna- 

 ments, 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 enter- 

 prise 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 ene- 

 mies, defend themselves and their own with 

 the desperate energy which, as displayed by 

 our own ancestral relations, we term patriot- 

 ism 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 near- 

 ly pure, still, owing to its formation in 

 needle-like crystals, considerable foreign mat- 

 ter 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 spe- 

 cies of bacteria on the surface of the water 

 may take place, and the first inch of ice may 

 contain these in increased numbers as com- 



pared 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 hag 

 undoubtedly, Mr. Platt affirms, been pro- 

 duced 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 con- 

 sidered, but their kind, and insists that no 

 water supply that is not fit for drinking pur- 

 poses should be used as a supply for ice. 

 This is done when ice is gathered from stag- 

 nant 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 impuri- 

 ties, 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 hi the orange groves at 

 Riverside, Cal. In some winters the tem- 

 perature falls so low that the oranges are 

 destroyed or injured. As a remedy the cul- 

 tivators are using appliances for warming 

 the orchards on a large scale. Their experi- 

 ments 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 



