8 THE NA TURE-STUD Y BE VIEW [6:1-j an., 1910 



among the cooking utensils, dumb waiters, refrigerating ma- 

 chinery, vacuum cleaners, laundry machinery, steam dryers, de- 

 vices for controlling temperatures, fireless cookers, steam or 

 electric heaters, coffee perculators, double boilers, thermos bot- 

 tles, ice cream freezers, chafing dishes, cofifee mills, egg beaters, 

 electric Hghts, electric bells, telephones, machanical piano play- 

 ers, sewing machines, electric irons, children's mechanical toys, 

 the baby's go-cart, bicycles, clocks, watches, fountain pens, trol- 

 ley cars, etc. 



It goes without saying that young people who dwell out- 

 side of large cities will have abundant contact with machinery^ 

 in these days when nearly every man who earns a living on a 

 farm or in a shop does so by operating some machine. 



The children should study interesting accounts of the strug- 

 gles, trials and successes of inventors and their inventions. 

 Goodyear and vulcanized rubber; Elias Howe and the sewing 

 machine; Stevenson, Fulton, Watt, and Bessemer, and promot- 

 ers like Morse of the telegraph, Field of the Atlantic cable, 

 Marconi of wireless telegraphy and Edison the inventor and 

 promoter of appliances innumerable. Cooking and other do- 

 mestic processes furnish countless illustrations which belong to 

 the realm of physical science: Combustion, canning and pre- 

 serving; cracking of fats in frying and roasting; combustible 

 vapors formed from a kettle of hot lard; characteristics of boil- 

 ing cocoa, milk, soap suds, etc., compared with those of boiling 

 water; osmose; diffusion; emulsion; charring. Bread gets dry, 

 and crackers get moist. Changes of starch and sugar; action 

 of baking powder, yeast, soaps and other cleansers ; disinfectants. 

 Effect of water, alcohol, hot dishes, etc., upon polished tables; 

 bleaching; fading; tanning; soldering; welding; tempering; 

 sharpening knives; properties of iron, tin, brass, copper, alumi- 

 num and silver; rusting; tarnishing; alloys, galvanized iron, 

 agate iron, enamelled and plated ware. What is there in iron 

 which should make two stoves which look alike cost such wide- 

 ly different prices? Why should one knife cost 25c, and an- 

 other $1.50? 



Physics and chemistry quite as much as biology lead us 

 to hygiene and the public welfare. Teachers have done much to 

 make boards of health possible. They have aided the move- 

 ment for introducing fresh air into public buildings. Let us 

 next propose to ventilate, filter, and humidify the air of large 



