PART II

NON-NATURAL FEATURES

XV. THE CANALS 173

XVI. THEIR SYSTEM 184

XVII. GEMINATION OF THE CANALS 192

I. THE DIPLOPIC THEORY 196

II. THE INTERFERENCE THEORY 201

III. THE ILLUSION THEORY 202

XVIII. THE DOUBLE CANALS 204

XIX. CANALS IN THE DARK REGIONS 243

XX. OASES 249

XXI. CARETS ON THE BORDERS OF THE GREAT DIAPHRAGM 265

XXII. THE CANALS PHOTOGRAPHED 271