Having been honoured once again with a request that I should lecture
before the London Institution, I chose for my subject the Theory of
Tidal Evolution. The kind reception which these lectures received has
led to their publication in the present volume. I have taken the
opportunity to supplement the lectures as actually delivered by the
insertion of some additional matter. I am indebted to my friends Mr.
Close and Mr. Rambaut for their kindness in reading the proofs.