LIST OF ILLUSTRATIONS 



FIG. SECT. PAGE 



1. Interrelation of the Sciences . . . . 21 12 



2. Four right angles ....... 31 18 



3. Angular measurement of distance . . . . 33 20 

 4.*Inverse Squares ....... 36 22 



5. Swing of a pendulum ...... 54 33 



6. Wave-motion 57 35 



7. Prismatic Refraction ...... 62 37 



8. Diagram of the Solar Spectrum . . . 63 39 



9. Curvature of the Earth . . . . . . 81 49 



10. Direction of rotation round North Pole . . 88 53 



11. Direction of rotation round South Pole . . 88 54 



1 2. *Diagrammatic section of the Earth . . . 93 58 



13. Revolution of a non-rotating body .... 102 67 



14. Revolution of a body rotating in the same time . 102 67 



15. Problem of the Earth and Sun . . . .106 70 

 i6.*Ellipse representing Earth's Orbit . . . . 109 72 



i7.*Cause of the Seasons 121 80 



1 8. Angle of Light Rays 124 82 



i9.*Zones of Climate . . . . . . . 125 83 



