294 



NATURE STUDY REVIEW 



[9:9— Dec, 1913 



Sound is one of the most 

 useful topics of physical science 

 for use in nature-study. An 

 excellent somometer is made 

 by fastening a wire to a door 

 hinge and passing the other 

 end around the knob. Musi- 

 cal instruments such as the 

 violin, brought by a pupil, 

 also illustrates laws of musi- 

 cal sound. 



Emphasis should be laid 

 upon experiments tending to 

 prove that all sounds are pro- 

 duced by vibration. 



Transmission of sound, its 

 speed and so forth, should 

 receive attention and be 

 demonstrated by such methods 

 as those suggested by fig. 5. 



Doubtless the most attrac- 

 tive nature-study especially to 

 boys is that chosen from the 

 field of electricity and mag- 

 netism. There is a good deal 

 of ground which :aiay be cover- 

 ed without making the work 

 too technical but a mention 

 here of one or two topics for 

 discussion is all that space 

 will permit. 



Electro-magnetism, being 

 the basis of most of our electri- 

 cal appliances, should be 

 demonstrated. A large nail 

 or small bolt wrapped a hun- 

 dred or more times with a few 

 cents worth of about No. 25 magnet wire purchased at an electri- 

 cal store will, when attached to a dry cell, become a powerful 

 magnet. 



© 



