THE

ENGINEER'S AND MECHANIC'S

ENCYCLOPAEDIA,


PIANO-FORTE. A musical instrument, resembling the harpsichord, (of which it is an improvement,) in which the the tone is produced by hammers, instead of quills, upon the strings. Of all the keyed instruments, as observed in the Oxford Encyclopaedia, the piano-forte seems to merit the preference, on account of the superior tone, sweetness, and variety, of which, by the ingenuity of British artists, it has now become susceptible. It was, as early as the beginning of the last century, that hammer-harpsichords were invented at Florence, of which there is a description if the Giornale d'Italia, 1711. The invention made but a slow progress ; the first that was brought to England was by Father Wood, an English monk at Rome. The tone of this instrument was so superior to that produced by quills, with the additional power of producing all the shades of piano and forte by the finger, and though the touch and mechanism were so imperfect that nothing quich could be executed upon it, yet the Dead March in Saul, and other solemn and pathetic strains, when executed with taste and feeling, by a master a litttle accustomed to the touch, excited equal wonder and delight to the hearers. Backers, a harpsichord-maker, constructed several piano-fortes ; and although he improved the mechanism in several respects, he failed in the tone. After the arrival of John C. Bach in this country, and the establishment of his concert, in conjunction with Abel, all the harpsichord-makers tried their mechanical powers upon piano-fortes ; but the first attempts were always on the large size, till Zumpé, a German, constructed small piano-fortes, of the shape and size of the original, of which the tone was very sweet, and the touch, with a little use, equal to any degree of rapidity. Pohlman, whose instruments were very inferior in tone, fabricated a great number for such persons as Zumpé was unable to supply. Large piano-fortes afterwards received great improvements in the mechanism by Merlin, and, in the tone, by Broadwood, Stoddart, Clementi, and others. The harsh scratching of the quills of a harpsichord can now no longer be borne. A great number of improvements have been made of late years, which have been the subjects of numerous patents. Some of these we now proceed to notice.

The first which presents itself to our attention is the patented improvement of Mr. Wheatston, of Jermyn-street, for augmenting the tone by the introduction of drums, or similar vibrating surfaces, against which sounds elicited reverberate ; these, it is said, not only augment the tone, but improve the melody. For this purpose, wooden frames are fitted to the inside of the instruments, upon which is tightly stretched paper, parchment, vellum, or similar substances, which constitute the drum. These, being placed as near as possible to the sounding-boards of the instruments, are powerfully acted upon by the vibration of the notes given out ; and to conduct the sound elicited with greater effect to the ears of the auditory, trumpet-shaped apertures are made through the cases of the instruments.

To give to piano-fortes the rich and lengthened tones of the violin, a patent was taken out by Mr. Todd. This is effected by the pressure of the foot of the player upon a pedal, which puts in motion an endless band (furnished with powdered resin,) which is made to rub against the particular wire in connexion with thet key that is depressed by the finger of the player ; and thus the same effect is produced as by the bow over the strings of the violin. Instruments so constructed will therefore have two distinct sets of tones ; that it, when the pedal is acted upon, the lengthened and beautiful tones of the violin will be produced ; without it, those of the ordinary piano.

The invention is not, however, confined to piano-fortes, but to all other instruments wherein the sounds are produced by the vibration of wires, or strings of catgut ; but the most eligible instrument for its application, is thet piano, more especially those of the upright or cabinet kind, The annexed diagram we have therefore selected from the specification, to explain the construction and modes of action of this ingenious contrivance, when applied to piano-fortes of the latter description. The figure gives a vertical section of the part ; thus a shows one of the wires stretched across the bridges, by means of tension pins over the body of the instrument. c c is an endless band revolving over two cylinders, which are set in motion by the treadly d, operated upon by the pedal ; this band is to be made of cloth, catgut, or other material capable of holding powdered rosin. e e is a frame of wood on which is made to turn a swinging piece f, and there are as many of these frames and seinging pieces as there are keys to the instrument. On each swinging piece are fixed wires, bent in the maner shown ; their ends are reduced to a conical figure to form centres, upon which revolve small brass rollers, as that at g. h is one of the keys of the instrument moving on its fulcrum pin, and its two stops are shown at i i ; a vertical stem of wood j is fixed into the key, carrying above it, in a horizontal position, a wire k, which acts upon the swinging piece f ; the wire k is fixed to the stem j by means of nuts placed on either side of the stem, which screw on to the end of the wire, and by these means the extent of motion to be given to the swingin piece is regulated. It will now be seen that when any key is depressed by the finger of the player, the little brass roller g is pressed against the endless band, which, bending it a little out of the right lin, causes it to rub against the wire a, and thereby produce a similar effect to the drawing of the bow over the strings of a violin.

The next invention which we shall notice is that of Mr. James Stewart, of George-street, Euston-square, who had a patent for it in 1830. It will be observed that there are several motions connected with the operations of a piano which require great precision as to their time, duration, and intensity of action. THe hammer must be made to strike the string at the same instant that the damper is withdrawn, and the hammer having done its duty must be instantly removed (even before the finger of the performer has left the key,) from the string, to allow the vibration to take place, and then that the damper must return to stop the vibration of the string the moment that the finger is withdrawn from the key. Now as all the motions must be obtained by a very slight touch of the finger, and without any noise, the levers and connecting rods, by which they are transmitted from the keys to the strings, become important considerations with piano-forte makers, and Mr. Stewart has simplifief the action, and rendered it more certain, by the introduction of a short lever placed over, and parallel with the interior end of the finger lever. This lever being short, and joined near its movable end by a small conecting brass rod to the finger lever, furnishes in itself the reqiored variety of motions, by placing the rods which act upon the hamer, damper, &c. at different distances from the fulcrum on which it turns. In addition to this, Mr. Stewart has intruduced an improved inclined plane for receiving the tail of the hammer, and stopping it silently, after it has struck the string.

To obviate the objections which have been raised to the elevated casing of the upright or cabinet piano-fortes, especially those whose fronts are covered with silk, which have a tendency to deaden the voice in case of accompaniment, Mr. Simon Thompson, of Yarmouth, has contrived to obviate the necessity of any portion of the instrument rising above the locking board, so that the top of the instrument is flat like a table. This object he effects by lowering the string frame, till its upper surface coincides with the top of the locking board, and making the keys bent lever, turning twice at right angles betwen the fulcrum on which they move, and the extremities which act upon the hamers. On the inner ends of each key, rests an upright guide wire, or slight rod, and to this are attached various projecting pieces which actuate the hammers, the dampers, &c. much in the usual manner ; so that this improvement, which is a very important one, is obtained without in the smallest degree altering the other parts of the instrument.

The spirit of improvement in this interesting branch of art seems recently to have equally pervaded our transatlantic brethren. In the Journal of the Franklin Institute, (which contains accounts of all the American patents,) we observe one by Mr. Jesse Thompson, of New York, dated October, 1830, for an improvement in the action of the upright piano-forte, some points in which our own manufacturers may deem worthy of adoption in a modified form. The following claim attached to the specification of this ppatent, will give to those acquainted with the subject a general idea of the variations introduced in this action. "What I claim as new, and as my own invention, is, first, the application of the finger lever directly to the food of the connecting rod, dispensing with the jack, springs, and all intermediate gearing. By this more immediate operation of the finger on the hammer, no time is lost between the touch and the blow ; the action is more controllable by the finger ; the blow is quicker, and more powerful ; the hammer can never block ; it relieves less from the string, and requires much less depth of touch. The simplicity of its construction renders the work much cheaper, and less liable to get out of order , than any known action. From this perfection of the action, I have been able to render the span fo the natural action to six and a half inches, and the others in proportion, without in any degree interfering with a clear and rapid execution : or the common span of the octave may be retained. Second, the placing the dampers below th hammer rail, by which positino the dampers fall on the brass strings near the middle of them, and thus more instantaneously and effectually stop their vibration, and may be raised by the simpler and cheaper modes herein specified."

The introduction of cast iron into the framing of piano-fortes, in lieu of the cumbrous masses of wood previously used, to resist the tension of so many wires, was a great modern improvement, to which we believe we stand indebted to M. Pleyel and Co., of Paris. At the present time the substitution of metal for wood is general.

This part of the mechanism was considerably improved by Mr. J. C. Schwieso, of Regent-stret, for which he obtained a patent in 1831. The string board of the piano-forte is secured between a stout cast iron fram, and to the latter is cast a projecting plate, through which the tuning pins pass. These tuning pins are made of steel, their lower ends are turned cylindrical, for coiling the ends of the wire, and the upper ends are made square for the reception of the key. To give these tightening pins the requisite friction to retain any required degree of tension on the strings, and enable them to be turned with facility, they are tapped below the square head to receive a nut, which screws against the upper side of the projecting plate, and they have underneath a collar and washer, which are drawn against the plate by the action of the nut above, leather washers being also interposed to give a degree of elasticity to the bearing parts. To produce the requisite friction, the nuts are screwed up ; and in order that the pins may be turned at pleasure, without altering the friction by which they are held, each nut is perforated with two holes, and the square key which fits over the square heads has at its extremity two projecting pins, which enter the holes in the nuts, and therefure turn the pins and nuts together without altering the friction. Mr. Schwieso applies tightening pins of this kind to the harp and violin.

Since the introduction of cast-iron frames for piano-fortes, considerable expense has been incurred in drilling the holes for, and fitting in the pins, so as to give them the properties mentioned in Mr. Schwieso's patent. To remedy these inconveniences, Mr. W. Allen, of Catherine-street, Strand, casts two dovetailed grooves along that end of the frame where the tightening pins are to be inserted, into which he drives pieces of wood of a corresponding shape, to fill up the dovetailed grooves, and receive the tuning pins. It is evident, that by this ingenious and simple contrivance, the expense of manufacture will be diminished, and the instruments will be improved.

Self-acting Piano-fortes have of late years been introduced : they combine the most rapid and brilliant execution with distinctness and neatness. Their harmony is necessarily more full than con be produced by eight fingers, the elements of chords having no other limit than the extent of its scale ; the time cannot be otherwise thant perfectly equable throughout, yet where pathos is to be expressed, the time can be accelerated or retarded in any degree. The mechanism of a self-acting piano-forte usually or principally consists of a cylinder turning horizontally on its axis, acted upon by a coiled spring, and regulated by a fly-wheel. On the surface of the cylinder, a determined arragement of brass pins is formed, each of which, in passing under a rank of levers, elevates one end of the required lever, and depresses the other. The depressed end pulls down with a slender rod, which is connected by a slide with the tail of a bent lever, on the further end of which is the hammer which strikes the string. The slide can be shifted further from, or neared to the axis, on which the hammer lever turns, and thus the stroke of the hammer is made feeble or strong to any required degreee. When would up, the instrument will continue to play for a considerable time ; and it is provided with a mech of keys like the ordinary piano-forte, so that a person may accompany the instrument, or play a duet with it.

A very beautiful instrument of this kind we have seen, that was manufactured by Clementi and Co. ; it had two barrels, each of which played nine tunes. The velocity was regulated by two revolving balls, similar to the governor of a steam-ngine.

Messrs. Rolfe and Sons, of Cheapside, have distinguished themselves in this branch of art by several improvements, which were the subject of a recent patent. These improvements they divide into three sections ; and their self-acting piano-fortes are constructed either with the first section only, or with the first and second section combined, or with the three sections united. The first section consists of a new apparatus for effecting the transitions of forte and piano, by which means the difficulty of producing those desirable changes is removed, by transferring the mechanical action from the weakest and most uncertain part of the arrangement, viz. the cylinder, to the more powerful and certain action of the engine, by which transfer the liability to derangement in instruments intended for exportation is avoided. To this branch of their patent, Messrs. Rolfe and Sons have annexed a hand movement, or register, by which the existing arrangement, or distribution of forte and piano, may at any time be changed, or altered to suit particular views, or may at any moment e removed from the government of the self-acting apparatus which produces the effect, and be operated upon by the hand, and again be restored to the control of the machine, at pleasure.

The second section consists of a new barrel movement for changing the tunes, which is effected by the introduction of an inclined plane, which forms an abutment for the axis of the cylinder. This plane is fived into eight portions, and is moved by a radial lever upon a pinion, which by its rotation one revolution moves upon a second dial an index to the extent of one eighth of its circumference, moving the inclined plane to a proportionate extent. By this simple arrangement the motions are rendered very steady and accurate, and eight distinct airs may thus be performed.

The third section consists in the application of a set of dampers to the self-performing action, which are altogether independent of the dampers ; so that each note of the self-acting or mechanical part of the instrument, in common with each particular note of the finger actino, possesses its appropriate damper, connected wiht and identifued by its kindred note, hammers, or keys, and acting simultaneously therewith. In conjunction with the application of the mechanical dampers, suitable stables are introduced into the cylinders, which, acting upon each particular damper as occasion may require, suspends its operation, and enables them to retain the vibrations of any given note, or the root and relative intervals of harmonious combinations, in the same manner as the finger fo a performer sustains the vibration of chords, whose existence is to be prolonged by continued pressure of the keys, according to the duration expressed by the determined value given to them by the author in the composition performed. In addition to this, the whole set of mechanical dampers are occasionally raised by the cylinder, according to circumstances, in order to produce the effect, of full swell, of the open pedal when moved by the foot of the performer.


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