During the closing stages of the final editing of this symposium and when it was ready for the press, there came the tragic news of Dr. Harry Wexler's sudden and unexpected death on August 11. Inasmuch as the planning of completion of this publication was one of his last acts, the symposium which he had conceived and organized with such distinction memorial to Commander Matthew Fontaine Maury has also become a memorial to Dr. Wexler.