THE BOTTOM OF THE LAGOON.
"I thought so," said the Doctor, smiling, "and so I've arranged that we will go to the reef to-morrow morning to see how beche-de-mer is taken. "We must make an early start, so as to be there at daylight."
Further talk about the Society Islands was indefinitely postponed, and the party adjourned to bed. All were up in ample season on the morrow for the excursion to the reef.
The best time for visiting the reef is at low tide. The tides in the Society Islands differ from those in most parts of the world, by never varying from one day to another throughout the year. At noon and at midnight is the height of the flood, and at six o'clock morning and evening is the lowest of the ebb. Ordinarily the rise is about two feet; periodically twice a year there comes a tidal-wave that breaks over the reef with great violence, and sweeps across the lagoon to the shore.
Frank and Fred sought an explanation of this tidal peculiarity, but were unable to obtain a satisfactory one. A resident of Papéiti said the tides were so certain in their movements that many people were able to tell the time of day very nearly by a glance at the reef.
