i6o NA TURE-STUD Y REVIEW [11 :3— Mar., 1915 



IV. Forest trees. 



Study of trees found around Mankato which may grow elsewhere in 

 forests. 

 Problems — 



How may the different species of trees in the following groups be 



identified: oaks, ashes, maples, elms, evergreens? 

 How are the fruits of trees adapted for seed dispersal? 

 What references are found to trees in literature? 



V. Means of Travel. 



1. On land. 



A. Steam cars — the steam engine. » 



B. Street cars — the motor. 



C. Automobile — the gasoline engine. 



D. The motor cycle. 

 Problems — 



How does the steam engine work? 



How does the gasoline engine differ from the steam engine? 

 How is the motor constructed? 



Which is the more useful, the steam engine, the motor, or the gaso- 

 line engine? 



2. On water. 



Steamboats, sail-boats, submarines; Archimedes principle. 

 The compass, the gyroscope. 

 Problems — 



How is the modern steamboat constructed? 

 How does one manage a small sail-boat? 



Why is the gyroscope sometimes used on ships instead of the com- 

 pass? 

 We will perform some simple experiments to learn why a canoe or 

 boat floats when it is loaded. 



3. In air. 



A. Aeroplanes ; use of barometer to tell height. 



B . B alloons— common and dirigible. 

 Problems — 



What are the differences between the aeroplane and the dirigible 



balloon? 

 Which offers the greater possibilities of usefulness? 

 How can the air man tell how high he is? 

 In what way is a balloon in the air like a boat on water? 



VI. Means of Communication. 



1 . The telephone. 



2. The telegraph — both common and wireless. 

 Problems — 



How are the telephone and telegraph constructed? 



Which is the more useful? 



How does the wireless differ from the ordinary telegraph? 



