BOOKS RECOMMENDED. 125 



Marvels of the Elements. 



Marvels of Heat, Light and Sound. 



Marvels of Invention and Scientific Puzzles. 



Marvels of Earth, Air and Water. 



Marvels of Geology and Physical Geography 



Marvels of Electricity and Magnetism. 



Marvels of Astronomy. 



Marvels of Animal and Plant Life. 



Half Hours of Scientific Amusement. 



