problem was to secure a fuller tone, with more sustained or 'singing' quality, and more variety. For this longer, heavier and tenser strings were demanded. At the same time the compass of the keyboard was being stretched from 4-5 octaves in the earlier patterns to 5½ and 6 before 1795, and to 7 by about 1825, with two or three strings to most of the keys. Hence the strain upon the frame was mounting up prodigiously. Hitherto the frame had been made wholly of wood, most ingeniously built up. In 1799 a London patent was taken out for longitudinal metal braces, and by 1808 Broadwood began to use steel tension-bars; but the union of wood and metal was not altogether successful. In 1825, however, the first full iron frame in one piece was introduced by Babcock of Boston, Mass., and in 1831 a similar feature appeared in London. Metal frames, either of combined sections or cast solid, soon generally displaced the old wooden ones, except for small instruments. For a time the union of different materials necessitated 'compensating' devices to meet variations in temperature. The important safeguard of 'agraffes' to keep the strings from being displaced by the hammer-blows was first used in 1808. 'Overstringing' came in about 1835, allowing for a decided consolidation of the frame.
In the search for sonority the character of the string-wire was a critical point. In the 18th century only brass or iron was used, but of so poor a quality that no great tension was possible. In the early 19th, brass was gradually given up and the iron was much improved. In 1834, if not earlier, the introduction of steel wire changed the whole problem, making possible the enormous tensions now common (amounting in present concert grands to 20-30 tons!). Still another most important factor was seen to be the material, form and fitting of the soundboard—a matter that was mainly settled empirically, as in the shaping of the body of the violin.
In the 18th century the two standard forms of piano were the 'grand' (shaped like the harpsichord) and the 'square' (like the clavichord). In 1800 Hawkins of Philadelphia patented the first true 'upright,' which involved radical modifications of both frame and action. This type was soon developed in Europe and became a favorite, as it still remains.
In the long line of distinguished piano-makers, following pioneers like Broadwood and Stein (see sec. 160), the following may be named as specially enterprising at this period in invention or the establishing of factories:—
Sébastien Érard (d. 1831), after returning from London to Paris in 1796 (see sec. 160), made his first grand, in 1809 introduced agraffes and worked out the principle of the 'repeating' action (patented by his nephew in 1821), and contributed to the betterment of the harp and the reed-organ. Pierre Érard (d. 1855), his nephew, worked first as his uncle's representative at London, but later became the head of the establishment at Paris. The latter published a treatise on the Érard system in general (1834).
In Germany the great firm of Schiedmayer was founded at Erlangen in 1781 by Johann David Schiedmayer (d. 1806), transferred in 1809 to Stuttgart by his son Lorenz Schiedmayer (d. 1860), and greatly developed by four
