The Book of Chronicles was an electronic book that allowed the user to record video footage of events that he or she witnessed.
History
Nothing is known of the Book's history, aside from the fact that it was in the possession of Turaga Nokama by the time that the Toa Mata arrived. After a wandering Matoran named Takua helped to save Ga-Koro from a Tarakava attack and Po-Koro from an epidemic, Turaga Onewa decided that the valiant Matoran was worthy of being the island's Chronicler, and gave Takua a golden chisel to give to Nokama as a sign of the Stone Turaga's faith in the Matoran.
After giving it to Turaga Nokama, Takua was appointed to the position of Chronicler by the Turaga of Water, Takua received the Book of Chronicles from her; this would enable him to record his experiences during his travels around the island, and so that even if something happened to him, they would still have a full record of the events he witnessed.
Takua presumably used the Book of Chronicles for the rest of his tenure as Chronicler; it is unknown if it was used by his successors in the position, Hahli and later Kopeke.