A course of scientific lectures designed for the general public must necessarily consist in large part of elementary and well known material, selected and arranged to develop the principal line of thought. It is expected that lectures under the auspices of the Lowell Institute, however elementary their foundation, will present the most recent progress of the science. The explanations of general principles and the accounts of recent researches must be brief and often incomplete; nevertheless it is hoped that the lectures in book form will furnish a useful basis for more extended study, and to further this end they are supplemented by references to sources of additional information. The references are collected in an appendix, citations being made by numbers in the text corresponding to the numbers in the appendix.
It is further expected that such lectures will be accompanied by experiments and illustrations to the greatest possible degree; the nature and extent of this illustrative material is shown as well as may be by the aid of diagrams and pictures, nearly all fo which have been especially prepared, and much care has been taken to make them as expressive as possible of the original demonstrations and explanations.
The methods and instruments used in sound analysis by the author, and many of the results of such work, were described in the lectures in advance of other publication and it is the intention to supplement the brief accounts here given by more detailed reports in scientific journals.
The author is greatly indebted to many friends for the kindly interest shown during the progress of the experimental work here described; and he is especially under oblication to Professor Frank P. Whitman of Western Reserve University, and to Mr Eckstein Case and Professor John M. Telleen of Case School of Applied Science, for many helpful suggestions received whilte the manuscript was in preparation.
DAYTON C. MILLER