§ 13. Mr. Philip Harry’s Sensitive Flame
§ 15. Constitution of Liquid Veins: Sensitive Water-jets
§ 1. Interference of Water-Waves
§ 3. Experimental Illustrations
§ 4. Interference of Waves from Organ-pipes
§ 5. Lissajous’s Illustration of Beats of Two Tuning-forks
§ 6. Interference of Waves from a Vibrating Disk. Hopkins’s and Lissajous’s Illustrations
§ 7. Quenching the Sound of one Prong of a Tuning-fork by that of the other
§ 1. The Facts of Musical Consonance
§ 2. The Theory of Musical Consonance. Pythagoras and Euler
§ 4. Sympathetic Vibration in Relation to the Human Ear
§ 5. Consonant Intervals in Relation to the Human Ear
§ 6. Graphic Representation of Consonance and Dissonance
§ 7. Composition of Vibrations
Fog-Siren
PREFACE TO THE THIRD EDITION
In preparing this new edition of “Sound,” I have carefully gone over the last one; amended, as far as possible, its defects of style and matter, and paid at the same time respectful attention to the criticisms and suggestions which the former editions called forth.
The cases are few in which I have been content to reproduce what I have read of the works of acousticians. I have sought to make myself experimentally familiar with the ground occupied; trying, in all cases, to present the illustrations in the form and connection most suitable for educational purposes.
Though bearing, it may be, an undue share of the imperfection which cleaves to all human effort, the work has already found its way into the literature of various nations of diverse intellectual standing. Last year, for example, a new German edition was published “under the special supervision” of Helmholtz and Wiedemann. That men so eminent, and so overladen with official duties, should add to these the labor of examining and correcting every proof-sheet of a work like this, shows that they consider it to be what it was meant to be—a serious attempt to improve the public knowledge of science. It is especially gratifying to me to be thus assured that not in England alone has the book met a public want, but also in that learned land to which I owe my scientific education.
Before me, on the other hand, lie two volumes of foolscap size, curiously stitched, and printed in characters the meaning of which I am incompetent to penetrate. Here and there, however, I notice the familiar figures of the former editions of “Sound.” For these volumes I am indebted to Mr. John Fryer, of Shanghai, who, along with them, favored me, a few weeks ago, with a letter from which the following is an extract: “One day,” writes Mr. Fryer, “soon after the first copy of your work on Sound reached Shanghai, I was reading it in my study, when an intelligent official, named Hsii-chung-hu, noticed some of the engravings and asked me to explain them to him. He became so deeply interested in the subject of Acoustics that nothing would satisfy him but to make a translation. Since, however, engineering and other works were then considered to be of more practical importance by the higher authorities, we agreed to translate your work during our leisure time every evening, and publish it separately ourselves. Our translation, however, when completed, and shown to the higher officials, so much interested them, and pleased them, that they at once ordered it to be published at the expense of the Government, and sold at cost price. The price is four hundred and eighty copper cash per copy, or about one shilling and eightpence. This will give you an idea of the cheapness of native printing.”
Mr. Fryer adds that his Chinese friend had no difficulty in grasping every idea in the book.
The new matter of greatest importance which has been introduced into this edition is an account of an investigation which, during the past two years, I have had the honor of conducting in connection with the Elder Brethren of the Trinity House. Under the title “Researches on the