XVII. IN THE LABORATORY

XVIII. INTO THE STORM

XIX. THE "LIGHTNING CAGE"

XX. THROUGH THE AIR

XXI. VAULTING TO THE RESCUE

XXII. "Z. 2. X."

XXIII. ON THE BORDER LINE

XXIV. "THE THREE BUTTES"

XXV. INTO THE BEYOND

XXVI. THE START FOR THE UNKNOWN

XXVII. THE PROFESSOR'S SECOND DILEMMA

XXVIII. THE UPPER REGIONS

XXIX. A MUD BATH

XXX. NIGHT ON THE COLORADO

XXXI. THE ISLAND OF MYSTERY