Then in the latter part of the eighteenth century Broadwood and Clementi of London and Erard of Strasburg and Petzold of Paris commenced the manufacture of their fine instruments. Erard particularly made many improvements in that and in the nineteenth century in the piano, its hammers and keys, and Southwell of Dublin in the dampers. By them and the Collards of London, Bechstein of Berlin, and Chickering, Steinway, Weber, Schomacher, Decker and Knabe of America, was the piano “ripened after the lapse of more than 2,000 years into the perfectness of the magnificent instruments of modern times, with their better materials, more exact appliances, finer adjustments, greater strength of parts, increase of compass and power, elastic responsiveness of touch, enlarged sonority, satisfying delicacy, and singing character in tone.” A piano comprises five principal parts: first, the framing; second, the sounding board; third, the stringing; fourth, the key mechanism, or action, and fifth, the ornamental case. To supply these several parts separate classes of skilled artisans have arisen, the forests have been ransacked for their choicest woods, the mines have been made to yield their choicest stores, and the forge to weld its finest work. Science has given to music the ardent devotion of a lover, and resolved a confused mass of more or less pleasant noises into liquid harmonies. In 1862 appeared Helmholtz’s great work on the “Law and Tones and the Theory of Music.” He it was who invented the method of analysing sound. By the use of hollow bodies called _resonators_ he found that every sound as it generally occurs in nature and as it is produced by most of our musical instruments, or the human voice, is not a single simple sound, but a compound of several tones of different intensity and pitch; all of which different tones combined are heard as one; and that the difference of quality or _timbre_ of the sounds of different musical instruments resides in the different composition of these sounds; that different compound sounds contain the same fundamental tone but differently mixed with other tones. He explained how these fundamental and compound tones might be fully developed to produce either harmonious or dissonant sensations. His researches were carried farther and added to by Prof. Mayer of New Jersey. These theories were practically applied in the pianos produced by the celebrated firm of Steinway and Sons of New York; and their inventions and improvements in the iron framing, in laying of strings in relation to the centre of the sounding-board, in “resonators” in upright frames, and in other features, from 1866 to 1876, produced a revolution in the art of piano making.