The writer wishes to acknowledge his great indebtedness to the various compilations relating to clockmakers and instruments which have been consulted in the preparation of this work, and which have provided an invaluable basis for it.

He is especially grateful for the generous and interested assistance of the many who have cooperated in making this work possible. Particular credit must be given to Mrs. H. Ropes Cabot of the Bostonian Society; Mrs. Mary W. Phillips of the Department of Science and Technology of the U.S. National Museum; Prof. Derek J. de Solla Price, Avalon Professor of the History of Science at Yale University; Mr. Stephen T. Riley, Director of the Massachusetts Historical Society; and Mr. Charles E. Smart of Troy, New York.