Part 17 (2/2)

THE SOUNDING-BOARD AND FRAME OF A PIANO

A piano has its strings strained across a _frame_ of wood or steel, fro square-ended pins in the bottoes near both ends

The tuner is able, on turning a pin, to tension its strings till it gives any desired note Readers e tension of a string is 275 lbs, so that the total strain on the fra between 20 and 30 _tons_

To the back of the fra-board_, made of spruce fir (the familiar Christmas tree) This is obtained from Central and Eastern Europe, where it is carefully selected and prepared, as it is essential that the tirain of the wood runs in the proper direction

THE STRINGS

These aresteel wire of the best quality If you examine the wires of your piano, you will see that they vary in thickness, the thinnest being at the treble end of the frae and the sahly-tensioned thick wires for the bass, and finer, shorter wires for the treble, taking advantage of the three factors--weight, tension, and length--which we have noticed above The wires for the deepest notes are wrapped round with fine copper wire to add to their weight without increasing their diahly one-third of a rand piano

THE STRIKING MECHANISM

We now pass to the apparatus for putting the strings in a state of vibration The grand piano135 may be taken as typical of the latest improvements The essentials of an effective mechanism are:--(1) That the blow delivered shall be sharp and certain; (2) that the string shall be immediately ”damped,” or have its vibration checked if required, so as not to interfere with the succeeding notes of other strings; (3) that the hammer shall be able to repeat the blows in quick succession The _haany covered with felt, the thickness of which tapers gradually and regularly from an inch and a quarter at the bass end to three-sixteenths of an inch at the extrehty-five haether in one piece, and then they are cut apart fro is very important If too hard, it yields a harsh note, andwith a needle In the diagram the felt is indicated by the dotted part

[Illustration: FIG 135--The striking e_ which operates the hammer is somewhat complicated

When the key is depressed, the left end rises, and pushes up the whole carriage, which is pivoted at one end The ha upon a knob, N, called the _notch_, attached to the under side of the shank When the jack has risen to a certain point, its arainst the button C and jerks it from under the notch at the very moainst the string As it rebounds, the haht on the _repetition lever_ R, which lifts it to allow of perfect repetition

The _check_ catches the tail of the ha its descent when the key is raised, and prevents it coe and rest The tail is curved so as to wedge against the check without jains to rise, the rear end of the key lifts a lever connected with the _da If the key is held down, the vibrations continue for a long time after the blow; but if released at once, the daains its seat A bar, L, passing along under all the _da the loud pedal The _soft pedal_ slides the whole keyboard along such a distance that the has allotted to all except the bass notes, which have only one string apiece, or two, according to their depth or length In soainst the strings; and a third kind of device s so that they deliver a lighter blow These two h-class piano is the result of very careful workulated by its tiny screws to a minute fraction of an inch It must be ensured that every ha, since on this depends the musical value of the note The adjustment of the dampers requires equal care, and the whole work calls for a sensitive ear coe, so that the instruth, and certainty of action throughout the whole keyboard

THE QUALITY OF A NOTE

If two strings, alike in all respects and equally tensioned, are plucked, both will give the same note, but both will not necessarily have the same quality of tone The quality, or _timbre_, as musicians call it, is influenced by the presence of _overtones_, or _harmonics_, in combination with the _funda

The fact is, that while a vibrating string vibrates as a whole, it also vibrates in parts There are, as it were, s fundamental waves Points of leastit into two, three, four, five, etc, parts, which , considered as halved by one node, gives the first overtone, or octave of the fundaive the second overtone, or twelfth of the fundaive the third overtone, the double octave

Now, if a string be struck at a point corresponding to a node, the overtones which require that point for a node will be killed, on account of the excessiveat that spot Thus to hit it at the middle kills the octave, the double octave, etc; while to hit it at a point one-third of the length from one end stifles the twelfth and all its sub-multiples

A fundamental note robbed of all its harret, as it is a et a rich tone we must keep as many useful harmonics as possible, and therefore a piano ha at a point which does not interfere with the best harmonics, but kills those which are objectionable Pianofortetone is excited when the point against which the hath of the wire from one end

The nature of theis also of importance The harder the substance, and the sharper the blow, the more proulate carefully both the duration of the blow and the hardness of the ha

[26] Tyndall, ”On Sound,” p 75

[27] A Broadwood ”grand” is made up of 10,700 separate pieces, and in its manufacture forty separate trades are concerned

[28] Twelve notes higher up the scale