A GRADED COURSE OF NATURE-STUDY 455 



derived from the use of machines and tools. Study in a 

 simple way, more for their practical use, some simple 

 machines.* Crowbar, lever, the incline, screw (book-press), 

 windlass, pulley. Point out the advantages gained by means 

 of each. (For references, see the last, also 289, 288, 292.) 



Discuss in a similar way, applying the principles already 

 learned: lamps,* chimneys,* stoves,* fireplaces, kites, wind- 

 mills,* sails,* water-wheels,* clocks.* Illustrate each by 

 observation of the actual object or experiment. Note the 

 natural agencies taken advantage of. Show how man has 

 learned to make these inanimate forces help him, just as he 

 has domesticated animals for his service. (References as 

 the last.) 



Metals: Identify common metals, test their useful prop- 

 erties. Note applications. Discuss why a particular metal 

 and not some other is used for special purposes. Espe- 

 cially emphasize the use of iron. 



Visit a blacksmith's shop.* (263, etc., 315, 317, 323.) 



Magnet :* Experiments with attraction. Make magnets. 

 Uses. Magnetic compass. Make one. (250,251,259,318, 

 340, 449.) 



Chemistry: Experiments to show in a simple way the 

 process of combustion. Study charcoal (carbon). Make 

 oxygen gas. Show power to support combustion. Burn 

 charcoal in oxygen. Show with lime-water the presence 

 of CO J. Observe the heat produced by the combustion. 

 Prove the formation of CO 3 by burning a candle. Illustrate 

 the production of heat by decay. Decay, a process of burn- 

 ing. Apply to hot-bed. (262, 263, 270, 272, 317, 317.) 

 Simple experiments to show nature of acid— muriatic, vinegar, 

 lemon; of alkah— lye, soap, soda. (274, 262, 263, 270, 272, 



