Just as the tone of a piano depends very largely upon the condition of the felts on the hammers which strike the wires, so does the tone of a clock gong or bell depend on its hammer action. The deep, soft, resonant tone in either instance depends on the vibration being produced by something softer than metal. Ordinarily this condition is reached by facing the hammer with leather. The second essential is that the hammer shall immediately rebound, clear of the bell, so as not to interfere with the vibrations it has set up in the bell, wire or tube. As the leather gets harder the tone becomes harsher and “tinny,” sometimes changing to another much higher tone and entirely destroying the harmony. The remedy is either to oil the leather on the hammers, or if they are much worn to substitute new and thicker leathers until the tone is sufficiently mellowed, so that a vigorous blow will still produce a mellow tone of sufficient carrying power. A piece of round leather belting will be found very convenient for this purpose.

The superiority of a chiming clock lies in its hammer action. If this mechanism is not perfect, only inferior results can be obtained. The perfect hammer is the one that acts with the smallest strain and is operated with the least power. Heavy weights create a tremendous strain on the mechanism and bring disastrous results when one of the suspending cords break. The method of lifting the hammer is one of importance, and the action of the hammer-spring is but seldom right on old clocks brought in for repairs, especially if it be a spring bent over to a right angle at its point. If there are two springs, one to force the hammer down after the clock has raised it up, and another shorter one, fastened on to the pillar, to act as a counter-spring and prevent the hammer from jarring on the bell, there will seldom be any difficulty in repairing it; and the only operation necessary to be done is to file worn parts, polish the acting parts, set the springs a little stronger, and the thing is done. But if there is only one spring some further attention will be necessary, because the action of the one spring answers the purpose of the two previously mentioned, and to arrange it so that the hammer will be lifted with the greatest ease and then strike on the bell with the greatest force, and without jarring, requires some experience. That part of the hammer-stem which the spring acts on should never be filed or bent beyond the center of the arbor, as is sometimes done, because in such a case the hammer-spring has a sliding motion when it is in action, and some of the force of the spring is thereby lost. The point of the spring should also be made to work as near to the center of the arbor as it is possible to get it, and the flat end of the spring should be at a right angle with the edge of the frame, and that part of the hammer-stem that strikes against the flat end of the spring should be formed with a curve that will stop the hammer in a particular position and prevent it jarring on the bell. This curve can only be determined by experience; but a curve equal to a circle six inches in diameter will be nearly right.

The action of the pin wheel on the hammer tail is also of importance. The acting face of the hammer tail should be in a line with the center of the pin wheel, or a very little above it, but never below it, for then it becomes more difficult for the clock to lift the hammer, and the hammer tail should be of such a length as to drop from the pins of the pin wheel, and when it stops be about the distance of two teeth of the wheel from the next pin. This allows the wheel-work to gain a little force before lifting the hammer, which is sometimes desirable when the clock is a little dirty or nearly run down. We might also mention that in setting the hammer-spring to work with greater force it is always well to try and stop the fly with your finger when the clock is striking, and if this can be done it indicates that the hammer spring is stronger than the striking power of the clock can bear, and it ought to be weakened, because the striking part will be sure to stop whenever the clock gets the least dirty.

Gong wires are also the cause of faulty tones. In the factories these are made by coiling wires of suitable lengths and sections on arbors in a lathe. They are then heated to a dull red and hardened by dipping in water or oil. After cooling they are trued in the round and the flat like a watch hairspring and then drawn to a blue temper. The tone comes with the tempering, and if they are afterwards bent beyond the point where they will spring back to shape the tone is interfered with. Many repairers, not being aware of this fact, have ruined the tone of a gong wire while trying to true it up by bending with pliers. When the owner is particular about the tone of the clock, a new gong should always be put in if the old one is badly bent.

The wires are soldered to their centers and if they are at all loose they should be refastened in the same manner if it can be done without drawing the temper of the wire. When this cannot be done a plug of solder may be driven in between the wire and the side of the hole so as to stop all vibration or the solder already in place may be driven down so as to make all tight, as any vibration at this point will interfere with the tone.

Tuning the Bells.—Bells only very slightly out of tone offend the musical ear, and they may easily be corrected to the extent of half a tone. To sharpen the tone make the bell shorter by turning away the edge of it if it be a shell, or by cutting off if it be a rod or tube; to flatten the tone, thin the back basin-shaped part of the bell by turning some off the outside. Bells which are cracked give a poor sound because the edges of the crack interfere with each other when vibrating. They may be repaired by sawing through the crack to the end of it, so that the edges will not touch each other when vibrating. If there is danger of the crack extending further into the bell, first drill a round hole in the solid metal just beyond the end of the crack, and then saw through into the hole; this will generally prevent any further trouble.

Marking the Chime Barrel.—The chime barrel in small clocks is of brass and should be as large in diameter as can be conveniently got in. To mark off the positions of the pins for the Cambridge chimes, first put the barrel in the lathe and trace circles round the barrel at distances apart corresponding to the positions of the hammer tails. There are five chimes of four bells each for every rotation of the barrel, and a rest equal to two or three notes between each chime. Assuming the rest to be equal to three notes, divide the circumference of the barrel into thirty-five equal parts by means of an index plate, and draw lines at these points across the barrel with the point of the tool by moving it with the slide rest screw. Call the hammer for the highest note D, and that for the lowest note F. Then the first pin is to be inserted where one of the lines across the barrel crosses the first circle; the second pin where the next line crosses the second circle; the third pin where the third line crosses the third circle and the fourth pin where the fourth line crosses the four circle, because the notes of the first chime are in the order, D, C, Bb, F. Then miss three lines for the rest. The first note of the second chime is Bb and the pins for it will consequently be inserted where the first line after the rest crosses the third circle, and so on. Where two or more notes on the same bell come so close as to make it difficult to strike them properly, it is usual to put in another hammer, as it shown in Fig. 121, where there are two Fs. In fine clocks the pins are of varying lengths so as to strike the hammers on the bells with varying force and thus give more expression to the music.

The following gives the Cambridge Chimes, which are used in the Westminster Great Clock. They are founded on a phrase in the opening symphony of Handel’s air, “I know that my Redeemer liveth,” and were arranged by Dr. Crotch for the clock of Great St. Mary’s, Cambridge, in 1793.

In Europe these chiming clocks are sometimes very elaborate, as the following description of a set of bells in Belgium will show:

“So far as the experience of the writer goes the Belgian carillons are invariably constructed on one prevailing plan, with the exception that the metal used for the cylinder is generally brass; here, however, it is of steel, and consists of a large barrel measuring 4 feet 2 inches in width and 3 feet 6 inches in diameter, its surface being pierced with horizontal lines of small square holes about ? inch square. There are lines of 60 of these in the width of the barrel, while there are 120 lines of them round the circumference, making a total of 7,200 holes. The drilling of these, of course, takes place when the cylinder is made, and, so far as this part is concerned, the barrel is complete before it is brought to the tower.

“Into these square holes are fixed the ‘pins,’ adjusted on the inside of the cylinder by nuts.

“The pins are of steel of finely graduated sizes, corresponding with the value of the notes of music. Some idea of the precision obtainable may be gathered by the fact, as the carillonneur told the writer, that there were no less than 24 grades of pins, so as to insure the greatest accuracy of striking the bells.

“Over the cylinder are 60 steel levers with steel nibs; these are lifted by the ‘pins’ and, connected by wires with the hammers, strike the bells.

“The 35 bells are furnished with 72 hammers, which are fixed as ordinary clock-hammers outside of the bells; three of the bells (in the ring of eight) have a single hammer only, the limited space in the ‘cage’ making it impossible to put more, while others are supplied with two or three apiece for use in rapidly repeating notes of the music. On a visit some years ago to the carillon at Malines, the writer noticed that some of the bells there had no less than five hammers apiece.

“Obviously, though there are 72 hammers in connection with the carillon, only 60, corresponding with the number of levers, can be used at one time; these are selected according to the requirement of the tune; in case of new tunes, the wires can easily be adjusted so as to bring other hammers and bells into use.

“The feature of the Belgian carillons is that instead of the single notes of the air being struck as with the old familiar ‘chimes’ harmonized tunes of great intricacy are rendered with chords of three, four or even five bells striking at one time.

“The cylinder here is capable of 120 ‘measures’ of music, but as, a matter of fact it is subdivided so that half a revolution plays every hour.

“A march is, as a rule, played at the odd hours, and the national air at the even, but the bells are silent after 9 p. m. and start again at 8 a. m.

“The motive power is supplied by a weight of 8 cwt., and is controlled by a powerful fly of four fans artistically formed to represent swans. It may be mentioned that the keyboard for hand-playing consists of thirty-five keys of wood and eleven pedals; these, as indeed the whole apparatus of this part, are entirely separate from the automatic carillon; in this instance the keys connect with the clappers of the bells and have no association with the hammers. The pedals are connected with the eleven largest bells and are supplementary to the hour key.”

Tubular Chimes are tubes of bell metal, cut to the proper lengths to secure the desired tones and generally, but not always, nickel plated. As they take up much room in the clock, they are generally suspended from hooks at the top of the back board of the case, being attached to the hooks by loops of silk or gut cords, passed through holes drilled in the wall of the tubes near the top ends. The hour tube, being long and large, generally extends nearly to the bottom of a six-foot case, while the others range upwards, shortening according to the increase of pitch of the notes which they represent.

This makes it necessary to place the movement on a seat board and hang the pendulum from the front plate of the movement, so that such clocks have, as a rule, comparatively light pendulums. On account of the position and the great spread of the tubes, the chiming cylinder and hammers are placed on top of the movement, parallel with the plates, and operated from the striking train by means of bevel gears or a contrate wheel. The hammers are placed vertically on spring hammer stalks and connected with the chiming cylinder levers by silken cords. This gives great freedom of hammer action and results in very perfect tones. The hammers must of course be each opposite its own tube and thus they are rather far apart, which necessitates a long cylinder. This gives room for several sets of chimes on the same cylinder if desired, as a very slight horizontal movement of the cylinder would move the pins out of action with the levers and bring another set into action or cause the chimes to remain silent.

Practically all of the manufacturers of “hall” or chiming clocks import the movements and supply American cases, hammers and bells. The reason is that there is so little sale for them (from a factory standpoint) that one factory could supply the world with movements for this class of clocks without working overtime, and therefore it would be useless to make up the tools for them when they can be bought without incurring that expense.