CONTENTS
[CHAPTER I.] THE POWER OF THE AIR
[CHAPTER II.] AN ENCOUNTER WITH A CHARACTER
[CHAPTER III.] THE PROFESSOR'S DILEMMA
[CHAPTER IV.] "WHERE IS HE?"
[CHAPTER V.] CHESTER CHADWICK—INVENTOR
[CHAPTER VI.] THE RADIO TELEPHONE
[CHAPTER VII.]THE GREAT TEST
[CHAPTER VIII.] TALKING THROUGH SPACE
[CHAPTER IX.] THE BOYS FACE TROUBLE
[CHAPTER X.] AN INVOLUNTARY AËRONAUT
[CHAPTER XI.] BY THE ROADSIDE
[CHAPTER XII.] MAKING ENEMIES
[CHAPTER XIII.] THE LEADEN TUBE
[CHAPTER XIV.] IN THE HOSPITAL
[CHAPTER XV.] A TALE OF THE COLORADO
[CHAPTER XVI.] ZEB CUMMINGS
[CHAPTER XVII.] IN THE LABORATORY
[CHAPTER XVIII.] INTO THE STORM
[CHAPTER XIX.] THE "LIGHTNING CAGE"
[CHAPTER XX.] THROUGH THE AIR
[CHAPTER XXI.] VAULTING TO THE RESCUE
[CHAPTER XXII.] "Z. 2. X."
[CHAPTER XXIII.] ON THE BORDER LINE
[CHAPTER XXIV.] "THE THREE BUTTES"
[CHAPTER XXV.] INTO THE BEYOND
[CHAPTER XXVI.] THE START FOR THE UNKNOWN
[CHAPTER XXVII.] THE PROFESSOR'S SECOND DILEMMA
[CHAPTER XXVIII.] THE UPPER REGIONS
[CHAPTER XXIX.] A MUD BATH
[CHAPTER XXX.] NIGHT ON THE COLORADO
[CHAPTER XXXI.] THE ISLAND OF MYSTERY
[CHAPTER XXXII.] THROUGH THE WOODS
[CHAPTER XXXIII.] THE SECRET AT LAST
[CHAPTER XXXIV.] THE INTERLOPERS
[CHAPTER XXXV.] TRIUMPH
[CHAPTER XXXVI.] THE HOMECOMING