Page:The Sources of Standard English.djvu/453

16

Airy (G. B.) — continued.

The undulatory theory of optics is presented to the reader as having the same claims to his attention as the theory of gravitation: namely, that it is certainly true, and that, by mathematical operations of general elegance, it ''leads to results of great interest. This theory explains with accuracy a'' ''vast variety of phenomena of the most complicated kind. The plan of this'' tract has been to include those phenomena only which admit of calculation, and the investigations are applied only to phenomena which actually have keen observed.

This volume consists of sections, which again are divided into numbered articles, on the following topics: — General recognition of the air as the medium which conveys sound; Properties of the air on which the forma&shy;tion and transmission of sound depend; Theory of undulations as applied to sound, &c.; Investigation of the motion of a wave of air through the atmosphere; Transmission of waves of soniferous vibrations through dif&shy;ferent gases, solids, and fluids; Experiments on the velocity of sound, &c.; On musical sounds, and the manner of producing them; On the elements of musical harmony and melody, and of simple musical composi&shy;tion; On instrumental music; On the human organs of speech and hearing.

As the laws of Magnetic Force have been experimentally examined with philosophical accuracy, only in its connection with iron and steel, and in the influences excited by the earth as a whole, the accurate portions of this work are confined to the investigations connected with these metals and the ''earth. The latter part of the work, however, treats in a more general way'' of the laws of the connection between Magnetism on the other hand and Gal&shy;vanism ''and Thermo-electricity on the other. The work is divided into'' Twelve Sections, and each section into numbered articles, each of which states concisely the subject of the following paragraphs.