It now remains to be shewn how the time or the lengths of the different notes are determined. Long or slow, short or quick notes, such as the minim and demi•semiquaver, arc not well suited to bell-music, and, of course, are seldom introduced into tunes chosen for it ; the crotchet, quaver, and semiquaver, forming the greatest part of the composi tion : the minim and demi•semiquaver may, however, be brought in at sonic parts. It may be unnecessary to state, what is pretty generally known, the proportional value of the notes to one another ; suffice it to say, that a minim is equal to two crotchets, a crotchet to two quavers, a quaver to two semiquavers, and a semiquaver to two demisemi quavers. The time in which the barrel turns, after strik ing or lifting a hammer-tail, to strike any note on a bell, must be in the same proportion with the notes, according to their respective character. Let a wheel of 25u teeth, for example, be fixed on the end of the barrel, and let both be placed in the turn-bench, with the apparatus which has been described : To the turn-bench is now attached a steel or brass spring, having a knee or bending at one end, so that it may Iall into the spaces of the wheel-teeth. The tune of the Jolly Young Waterman (Sec Plate CCCVIII. Fig. 5.) being proposed to be laid on the barrel, will, by in spection, be seen to contain 20 bars of three crotchets each, being 60 crotchets : ii 250 the number of the wheel is di vided by 60, the number of the crotchets, we shall have four for the quotient, and ten for the remainder ; shewing that we may take four teeth or spaces for every crotchet, ten, the remaining part of it, serving as a run for locking, and the other part for a run at unlocking, for a tune to be played. Now as a crotchet is equal to four spaces, a quaver must be equal to two, and a semiquaver equal to one. In the tune proposed, the first note is F ; the curved arm is brought to the left hand, and the flat steel piece put into that notch ; the punch is then made to mark the barrel ; and this being a semiquaver, or the fourth part of a crotch et, the spring index is shifted into the next space of the wheel teeth, and the curved arm moved to the next note, which is G, on the left hand, and the flat steel piece being put into the notch corresponding to G, the punch is made to mark it on the barrel. This being a semiquaver also, the spring is shifted into the next space,'and the curved arm moved to note A on the left ; the steel piece is put into the corresponding notch, and the punch marks this on the barrel. A is here equal to a quaver and a half; therefore the spring index must be moved over three, or into the third space, and the curved arm moved to the next note, being B, on the left hand ; the steel piece being put into this notch, the note is marked on the barrel ; and as it is a semiquaver, one space is taken for it, and the arm moved to G. This being marked, and as it is a quaver, two spaces are taken, and so on. When crotchets are marked, four spaces are taken after marking them. In the tune which we have used, time bells or notes are all that is required ; and three more, or a dozen, would give such a compass as to take in almost any tune that might be required. In place of the spring index, it would be better to have a single threaded endless screw to work into the wheel teeth, one turn or which would be equal to a tooth or space. The arbor of the screw being squared on one end, and a small handle for turning it being put on, there would be less danger of making mistakes with the screw than with the index. On the arbor of the screw there might also be put a hand or index, to point to a circular space or dial of eight or ten divisions. This would give room to make parts of a turn, where great nicety is required. After one tune is laid on the barrel, either it or the music scale must be shifted a short space when the next one is to be put on. To shift the music scale is perhaps the preferable way of the two ; and the spaces for shifting should be marked on the top of one of the supports, and close by one end of the long slip of brass ; or they might be marked on a short line drawn longitudinally on the surface of the barrel, at or towards one of the ends of it ; or by taking both methods; the one would serve as a check on the other. The length of shifting depends on the distance between the hammer tails and the number of tunes to be put upon the barrel. For example, if the distance between the hammer tails is four-tenths of an inch, and it is proposed to put eight tunes on the barrel, then, if we divide four-tenths by eight, we shall have half a tenth for the length or space to shift for each tune ; and this is taking advantage of the whole space between the hammer tails, a circumstance which is fre quently overlooked ; for where the shifts have been con fined to a less space for shifting than might have been got, so much room is lost. The distance between the hammer tails depends on their number, and on the length of the barrel. We have made the distance a quarter of an inch, where the number of hammers were eleven, and the length of barrel about three inches and a quarter, the number of tunes put on the barrel seven, the spaces for shifting were three hundred parts of an inch, or thereabouts, and where the clock of itself shifted the tune. When the hammer tails are thin, a number of tunes could be made to have their shifts in a very short distance between the tails ; the diameter of the lifting pins must also be taken into account, being of some consideration where the spaces for shifting are extremely limited. Although we have taken the num ber of the wheel teeth 'for dividing the notes at 250, yet either a gre'ater or less number may be assumed ; all that is required is to proportion the number of turns of the end less screw, and parts of a turn, to the number of bars in the tune;and to the notes in each bar, and to have the tunes to go nearly round the barrel, so that a small part of a revo lution of it, after the tune is played over, may be left for what is called locking and running. If the dividing wheel was taken at 128 teeth, and the tune being supposed to have 20 bars, each bar having three crotchets, as in the former example, 128 teeth divided by 60, the number of crotchets, the quotient would be two, and the remainder would be eight ; so that each crotchet would require two teeth or turns of the endless screw, a quaver one turn, and a semiquaver half a turn, and the remaining eight teeth would serve for locking and running. When the tunes are all marked on the barrel, each mark must be drilled to ob tain holes for the lifting pins to be driven into them. Great care should be taken to have a stiff and excellent drill, •so as to run no risk of breaking, which would occasion a great deal of trouble ; and it should be of such a temper, and well and judiciously whetted up, so that it may drill all the holes without requiring to be once sharpened up : the ob ject here is to have all the holes of the same width, so that the lifting pins may be all of the same diameter. The holes being drilled, and the barrel polished, a number of pins should be prepared into lengths of half an inch or so each, and a very little tapered at one end. The stronger and harder the brass wire for the pins is, so much the bet ter ; some of the best kind of pins used in the female dress are very fit for this purpose. In placing the pins in the holes, if they should be found too long for knocking in by the hammer, they should be shortened by the cutting plyers before the hammer is applied, which will prevent bending, and allow the pinsto have a more secure hold of the barrel rim. After all the pins are put in, they must now be short ened to an equal and proper length or height. For this purpose prepare a hard cylindrical steel collet, having a hole in its centre sufficiently wide to allow it to be put readily on the pins ; the lower end of it hollowed, the upper end round ed, and the height of the collet about one-twentieth of an inch or a little more ; the height depending on the size of the barrel and the diameter of the pins. The collet being
placed on a pin, the cutting plyers are applied to cut the pin just over by the rounded end ; a small touch of a file takes away the burr made by cutting, and as the hardness of the collet prevents the tile from taking any more away from the height of one pin than from another, they must be all of an equal height. This operation being finished, the small burrs made on the top of the pins by the file must be taken off; this is done by a piece of steel wire, about six or seven inches long. The end where it is twirled about by the fore finger and thumb should, for the length of an inch or so, be made into an octangular form, for the more readily turning it round back and forward. On the face or point of the other end, two notches are made across each other, which may be either angular or round at bottom ; the latter may be the better of the two, if rightly executed, and should be made with the round edge of a flat file, whose thickness should not be more than the diameter of the pins. The point where the notche's are cut should be hardened, and the inside and bottom of the notches polished, so that a sharpness may be given to take away the burrs easily from the top of the pins.
The shape of the hammer tail is such as is represented at Plate CCCVIII. Fig. 3, a form which makes the hammer easy enough to be drawn, and the tail takes little or no room when falling ; and should two pins or notes succeed each other rather rapidly, the nib or point of the hammer tail will not be interrupted by the succeeding pin. In the first musical clocks, and even in those made long afterwards, the bells were all placed on one strong iron bell stud, the oppo site end of which was supported by what may be called an auxiliary stud, which occasioned a crampness that prevent ed the bells, when they were struck by the hammers, from vibrating, or giving out that full tone which they might have otherwise been made to produce ; and the improve ment made on this, as well as on the quarter bell studs af terwards, was effected by placing each bell separately on its own bell stud, which was made of well hammered brass, having some degree of elasticity. The sweetness given to the tone of the bells by this method was truly surprising. The bells in this kind of music may be sounding at the time that a succeeding note is struck out and sounding too, which may not be so pleasant to a very nice ear. This can be prevented by having a double set of hammers, and having every tune pinned twice over on the barrel, one set of the hammers having the heads of buff leather, or having a brass head with a piece of cloth sewed over it. These, when they strike the bell, will damp the sound of the note which is last struck. The buff hammer should fall on the bell to be damped, at the same instant that the brass hammer strikes the succeeding note on its bell. This improve ment, however, must greatly increase the expense on such a clock ; but the effect of buff or cloth hammers is so strik ing, that the additional price ought not to be grudged.
In Plate CCCVIII. Fig. 3, AA is a circle representing an end view of a clock music barrel, and a few of the lift ing pins. The dart shows the direction in which it turns. The letters a, a, a, a, a, represent a section or end view of a brass piece thus shaped. The length depends on that of the barrel, and the number of hammers to be let into this brass piece, which is called the hammer frame, the length of it being sometimes three or four inches, sometimes ten or twelve. The flat part of the hammer tails fills up the thick part of the hammer frame, into which slits are made to receive the hammers. Near to the outer and lower an gular part at a of the frame, a hole h is made through the whole length of it, not drilled, but ploughed, as the work men call it, and this is done before any slits are made in it for the hammers. A wire is put through this hole, and through corresponding holes in the flat part of the hammer tails. This wire is their centre of motion, and the holes in them are made so as to have freedom on it, and the flat part of the hammer tails are also made to have freedom in the slits made to receive them. On the under side of the hammer frame at b, the hammer springs c, c are screwed, one for each hammer, acting on that part of the hammer tail just where it conies out of the thick part of the ham mer frame. When the pins in the barrel raise up any ham mer by the nib, and carrying it away from the bell, at the instant the pin quits the nib, the spring c, c, by its return ing force, makes the hammer head give a blow on the bell, to elicit the sound. To prevent any jarring in the bell by the hammer head resting or touching it after having given the blow, each hammer has a counter-spring, acting near the lower end of the shank, and inside of it. All the counter springs are made to project from one slip of well hammered brass, and screwed on the top of three kneed brass cocks, fixed to the upper side of the brass frame. d d is a view of the side of one of the cocks ; and e e an edge view of one of the counter-springs. f f is a side view of one of the bell studs, which are also screwed on the upper side of the hammer frame : an edge view is seen at ff, Fig. 4. g, g, g, g are edge views of the bells. g, g, Fig. 4. is a side view of one of them as fixed to its stud. In some musical clocks, in place of the barrel heing made to shift for change of tune, the hammer frame is made to shift, carrying with it all the hammers and bells. The change, or shifts of the barrel, is either done by hand or by the clock itself. The mechanism for this commonly consists of a wheel fixed on a steel arbor, on the square of which a hand is put, which points to the name or number of the tune marked on a small dial, at -which the barrel for the moment stands. The diameter of this wheel is about one inch and a half, and sometimes more or less. The rim is a strong and thick hoop or con trate form, having as many steps on it as there are tunes set on the barrel, the height of the steps being equal to the space from one tune to another. On these steps rest the kneed end of a double lever about four inches long, whose centre of motion is in the middle, and is either upon strong pivots run into a kind of frame, or upon a stout pin, which goes through the lever and the brass stud in which the le ver moves. The other end of the lever bears on the end of one of the pivots of the music barrel, which is pressed against it by means of a pretty smart steel spring, acting against the end of the opposite pivot. Concentric with the hoop wheel, and fixed on the same arbor, is a star wheel of a number according with the steps on the hoop wheel, a jumper with a pretty strong spring works into the star wheel, by which means the barrel is kept always to its place, by the lever bearing at one place on every step. Although the Figures which have been given to represent the hammer frame, hammers, springs, and counter-springs, bell studs, and bells of music striking, are not exactly like those which are commonly made to strike quarters in clocks, yet they are equally .veil calculated for the purpose ; only the nibs of the hammer tails need not be so far from their centre of motion, being less confined by the pins in the quarter barrel, which are fewer in number than those on a music barrel. A quarter barrel need not be much in di ameter, if five quarters are only to be put on it. If ten is intended to be put on, then the diameter should be double that of the other.