Introductory Cosmic Rays.- The Galaxy and the Interstellar Medium.- Extragalactic Cosmic Rays.- Sidereal Daily Variations in Cosmic Ray Intensity and their Relationships to Solar Modulation and Galactic Anisotropies.- Energy Spectrum and Mass Composition of Cosmic Ray Nuclei from 1012 to 1020eV.- Nuclear Mass Composition at ‘Low’ Energies (i.e.