486 NATURE-STUDY 



the engine, its parts, etc. Use diagrams and models to illus- 

 trate general principles. Do not make complex, simply the 

 principle of steam pressure and the action of the slide valve 

 and piston. Uses of the steam engine. What would be 

 some of the results without it ? Visit factory, power plant, 

 machine-shop. Examine school steam-plant. Brief study of 

 the locomotive and a modern passenger train. The engineer. 

 The mechanic. 



Sound: Simple principles; vibration, transmission, echo, 

 sounding-boards. Musical instruments to illustrate the 

 principles of quality and pitch — piano, violin, flute, whistle, 

 organ pipe, drum. The phonograph. Make a record. 

 Thomas A. Edison. The inventor. The physics of the 

 ear * and the voice.* 



Sources of light. Rays, sunbeams in dust, mirrors* and 

 reflection (very simple; do not try to construct image). 

 Uses of mirrors. Where do you seem to stand ? Move your 

 right hand. Which seems to move ? How is a mirror made ? 

 Study of shadows,* conditions. Experiment with a burning 

 glass.* Show in a dark room how the rays are brought to- 

 gether. Very simple study of a reading lens or magnifying 

 glass. Pin-hole camera.* 



References: Physics; 251, 259, 261, 450, 255, 318, 317, 

 25o> 257, etc. 



Invention: 292, 293, 294, 285, 288, 289, etc. 



Boys' books for construction and experiments: 279, 281, 

 283, 284. 



Weather: Review of atmospheric physics:* Moisture, 

 evaporation, condensation, clouds, precipitation, rain, snow, 

 ice, frost, convection, winds. Pressure and barometer.* 

 Relation between storms and pressure. Cyclonic storms, 



