(6) The "strings," made of steel wire, one end of each being fastened to the string-plate and the other coiled around tuning-pins in the wrest-plank. They increase in length and thick ness from the treble to the bass. In the bass, in order to make the rate of vibration slower, they are over-spun or wound around with fine copper or mixed-metal wire. For the lowest tones (A,-F2) only one wire is employed; for each tone (GI-C) two strings; and above that, three strings. One of the most remarkable dif ferences between the modern and old pianos is due to the vast increase in the tensile strength of piano wire drawn under modern methods. The breaking strength of English piano wire ranges from 225 pounds for No. 12 music, 0.029 inch diameter, to 650 pounds for No. 22, 0.052 inch diameter ; giving an ultimate tensile strength of 340,000 pounds to the square inch, about five times that of the best old hand-drawn wire.
(7) The the principal varieties of which have already been carefully described, and which consist of the entire mechanical de vice by which the hammers are propelled against the strings, including the keyboard and its row of keys, which are manipulated by the fingers. The keyboard of a modern piano has a com pass of seven octaves, A-A, or seven octaves and a minor third, A-C, ffie extreme notes of which are very near the limits of the power of the average human ear to distinguish musical sounds. Cristofori's pianos were four-octave instruments. The keys corresponding to the natural tones and called ((naturals)) are made of ivory, and those corresponding to the chromat ically altered notes and called "sharps" are made of ebony. They are shorter than the nat urals and are raised above them. When a key is pressed down its rear end rises and lifts the "jack," which throws the hammer against the strings. The hammers are attached to shanks of light wood, such as pear wood, hickory or white beech, sufficiently tenacious not to fracture under the hardest blow, and yet elastic enough to rebound. The wooden ham mer-head is covered with felt, of compressed sheep's wool, cut from one piece, and increasing in thickness from treble to bass. The texture of the felt should be neither too hard nor too soft. A hammer witha hard surface leaves the strings immediately after contact with it and allows the very dissonant upper partial tones to run their course, while a hammer with a soft surface dings slightly to the string, or at least long enough to clamp such discordant partials. Simultaneously with the throw of the hammer the "damper" is raised, thus allowing the string to vibrate freely, but by a "check" which pre vents its rebound. the damper remains raised as long as the key is pressed down and the string continues to vibrate.
(8) The "pedals," a set of levers, usually two in number, which are pressed down by the feet. They are called the "piano" and "fortes pedals; some makers add a third called a tone sustaining pedal. The left foot presses upon
the °piano') or soft pedal, which either throws all of the hammers cearer to the strings so that the striking distance is lessened by one-half, or by shifting the keyboard action bodily, removes the stroke of the hammer from three to two strings, one being left unstruck, but not silent, since it vibrates in sympathy with the sounding strings with which it is in tune. This sympa thetic vibration gives a beautiful molian tone quality that has been recognized by modern composers from. Chopin to Liszt as of much ad vantage. The "forte" or loud pedal is pressed by the right foot and raises all the dampers so that the strings struck continue to vibrate even after the keys are released. The "tone sustaining" pedal, although not invented by the Steinways, is often found in their grand pianos. It is an arrangement that, instead of raising all the dampers, allows the player to prolong any note or group of notes by keeping raised only such dampers as are raised by the keys when the pedal is down. In many upright pianos a soft pedal (Celeste) is applied by mechanically interposing a strip of thin felt be tween the hammers and the strings, thus ma terially diminishing the sound, and affording a great convenience in practising.
The earliest compositions for the piano forte appear in a volume entitled 'Sonate da Cimbalo di Piano e Forte, detto volgarmente di Martellatti.' Dedicato a Sua Altezza Reale. II' serenissimo D. Antonio Infante Di Porto gallo, e Composto da Lodovico Guistini di Pis toia. Opera Prima, Firenzi, 1732, the year after Cristofori died. The first compositions which showed a technique characteristic of the pianoforte are the three sonatas by Muzio Clementi, published in 1773. From that date the composers studied the new instrument and employed the proper technique, with the result, as in the case of Beethoven's magnificent piano forte compositions, that they went beyond the capabilities of the instruments of that time, and stimulated the piano-makers to increase both the compass and the power of the instruments. Increase in the power of tone demanded strings of greater thickness, while the extension of scale called for an increased number of strings, and, consequently, an enormous increase in the tension strain on the frame. These conditions led to the use of metal for frames, beginning with the hollow metal tube framing patented by Allen and Thom in 1820, followed by the cast iron frame of Babcock of Boston, in 1825, and the improvements of Jonas Chickering, who in troduced the full iron frame in 1837. Then came Steinway and Sons, who in 1859 intro duced the overstrung scale, permitting a much larger number of wires in a small space; thus the modern pianoforte was developed to its present state of perfection and power (see Fig. 11).