Unlike some other reproductions of classic texts (1) We have not used OCR(Optical Character Recognition), as this leads to bad quality books with introduced typos. (2) In books where there are images such as portraits, maps, sketches etc We have endeavoured to keep the quality of these images, so they represent accurately the original artefact. Although occasionally there may be certain imperfections with these old texts, we feel they deserve to be made available for future generations to enjoy.

Unlike some other reproductions of classic texts (1) We have not used OCR(Optical Character Recognition), as this leads to bad quality books with introduced typos. (2) In books where there are images such as portraits, maps, sketches etc We have endeavoured to keep the quality of these images, so they represent accurately the original artefact. Although occasionally there may be certain imperfections with these old texts, we feel they deserve to be made available for future generations to enjoy.

Unlike some other reproductions of classic texts (1) We have not used OCR(Optical Character Recognition), as this leads to bad quality books with introduced typos. (2) In books where there are images such as portraits, maps, sketches etc We have endeavoured to keep the quality of these images, so they represent accurately the original artefact. Although occasionally there may be certain imperfections with these old texts, we feel they deserve to be made available for future generations to enjoy.

Lord Rayleigh (1842-1919) won the Nobel Prize for physics in 1904. His early research was in optics and acoustics but his first published paper, from 1869, was an explanation of Maxwell's electromagnetic theory. In 1871, he related the degree of light scattering to wavelength (part of the explanation for why the sky is blue), and in 1872 he wrote his classic Theory of Sound (not included here). He became a Fellow of the Royal Society and inherited his father's peerage in 1873. Rayleigh nevertheless continued groundbreaking research, including the first description of Moire interference (1874). In 1881, while president of the London Mathematical Society (1878-1880) and successor to Maxwell as Cavendish Professor of Experimental Physics at Cambridge (1879-1884), Rayleigh published a paper on diffraction gratings which led to improvements in the spectroscope and future developments in high-resolution spectroscopy. This volume contains papers from 1869 to 1881.

This volume includes papers from 1887, when Lord Rayleigh became Professor of Natural Philosophy at the Royal Institution in London, to 1892. An 1888 contribution on the densities of hydrogen and oxygen led to a series of experiments on the densities of the atmospheric gases. This resulted in the unsettling discovery that the density of atmospheric nitrogen seemed very slightly to exceed the density of nitrogen derived from its chemical compounds. A substantial 1888 paper, on the wave theory of light, was written for the Encyclopaedia Britannica in the immediate aftermath of the crucial Michelson Morley experiment in which the speed of light had been measured. In addition, this wide-ranging volume shows Rayleigh's developing interest in the properties of liquid surfaces, with a discourse on foams (1890), and a paper on surface films (1892). It also includes a charming brief appreciation (1890) of James Clerk Maxwell's legacy to science.

This volume of Lord Rayleigh's collected papers begins with a brief 1892 piece in which the author addresses the troubling discrepancies between the apparent density of nitrogen derived from different sources. Intrigued by this anomaly and by earlier observations by Cavendish, Rayleigh investigated whether it might be due to a previously undiscovered atmospheric constituent. This led to Rayleigh's discovery of the chemically inert element, argon, to his 1904 Nobel Prize in physics, and to the discovery of all the 'rare' gases. Debate over the nature of Roentgen rays, is reflected in a short 1898 paper, written in the wake of their discovery. 1900 saw a key contribution, the elegant description of the distribution of longer wavelengths in blackbody radiation. Now known as the Rayleigh Jeans' Law, this complemented Wien's equation describing the shorter wavelengths. Planck's law combined these, in a crucial step toward the eventual development of quantum mechanics.

This final volume of papers by Lord Rayleigh covers the period from 1911 to his death in 1919. The first of the Solvay Conferences in 1911 played a key role in the foundation of quantum theory. Although invited, Rayleigh did not attend. His principal achievements lay in development and consolidation across classical physics, in which he continued to work. In a 1917 paper, he used electromagnetic theory to derive a formula for expressing the reflection properties from a regularly stratified medium. In 1919, he investigated the iridescent colours of birds and insects. Rayleigh continued his long-standing participation in the Society for Psychical Research, founded in 1882 for the study of 'debatable phenomena'. One of his last publications was his presidential address to that society, which considers several highly unorthodox views and practices. He concludes by asserting the importance to scientists of maintaining open minds in the pursuit of truth.

As Cavendish Professor of Experimental Physics at Cambridge University, Lord Rayleigh focussed his considerable energies on the study of electricity - building on the work of his illustrious predecessor, James Clerk Maxwell. This second volume of his papers, covering 1881-7, includes a series of four major contributions from 1881 and 1883 concerning the absolute determination of the ohm. Related reports include the measurement of current, and the electrical properties of various materials. A note from 1884 pessimistically predicts an absolute practical limit of less than 50 miles for a working telephone cable. In 1884, Rayleigh stepped down from his post as Cavendish Professor but continued his research work from his private laboratory. He proposed the existence of surface waves in a paper of 1885. These 'Rayleigh waves' roll along the surface of the earth and are responsible for producing most of the shaking experienced in an earthquake.

Lord Rayleigh served as President of Royal Society from 1905 to 1908, when he became Chancellor of the University of Cambridge. In 1904 he was awarded a Nobel Prize. He received the physics award while Ramsey, with whom he had conducted the research and announced the discovery of argon, received the Nobel Prize for chemistry. In 1906 he published his electron fluid model of the atom, a modification of Thomson's 'plum pudding' proposal. This was superseded by a series of other (also invalid) models, until Bohr's atomic theory of 1913. In 1907 Rayleigh published a detailed observational study on how humans can perceive sound and distinguish the directions of pure and complex tones. His interest in optics also continued, with a 1907 analysis of the theoretical basis for unusual banding patterns arising when polarised light was shone on diffraction gratings. This volume includes his papers from 1902 to 1910.

John William Strutt, third Baron Rayleigh (1842-1919), was an English physicist best known as the co-discoverer of the element argon, for which he received the Nobel Prize in Physics in 1904. Rayleigh graduated from Trinity College, Cambridge, in 1865 and after conducting private research was appointed Cavendish Professor of Experimental Physics in 1879, a post which he held until 1884. These highly influential volumes, first published between 1877 and 1878, contain Rayleigh's classic account of acoustic theory. Bringing together contemporary research and his own experiments, Rayleigh clearly describes the origins and transmission of sound waves through different media. This textbook was considered the standard work on the subject for many years and provided the foundations of modern acoustic theory. Volume 1 discusses the origin and transmission of sound waves in harmonic vibrations, the vibrations of bars, stretched strings, plates and membranes, through mathematical models and experimental discussions.

John William Strutt, third Baron Rayleigh (1842-1919), was an English physicist best known as the co-discoverer of the element argon, for which he received the Nobel Prize in Physics in 1904. Rayleigh graduated from Trinity College, Cambridge, in 1865 and after conducting private research was appointed Cavendish Professor of Experimental Physics in 1879, a post which he held until 1884. These highly influential volumes, first published between 1877 and 1878, contain Rayleigh's classic account of acoustic theory. Bringing together contemporary research and his own experiments, Rayleigh clearly describes the origins and transmission of sound waves through different media. This textbook was considered the standard work on the subject for many years and provided the foundations of modern acoustic theory. Volume 2 discusses theories of aerial vibrations, with discussions of experimental procedures of aerial vibrations in tubes and rectangular chambers, and the theory of resonators.