altogether better sounding quarters. The quarter bells are the 1st, 2d, 3d, and 6th of a peal of 6 independent of the hour bell ; and the following is their arrangement:—
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01 /3126 2(1 ( 3213 1326 3d 6213 1236 1st hour. ..10
The interval between each successive chime of four should be two or at most two and a half times that between the successive blows. At Cambridge it is three times, decidedly too slow; at Westminster twice, which is rather too fast ; at Worcester cathedral and most of the later large clocks 2J times, which sounds the best.
At Cambridge the chimes are set on a barrel which turns twice in the hour, as this table indicates, and which is driven by the great wheel with a great waste of power ; the clock is wound up every day. An eight-day clock would require a very heavy weight, and a very much greater strain on the wheels, and they arc alto gether inexpedient for these quarters on any large scale of bells.
Indeed there is some reason for doubting whether the modern introduction of eight-day clocks is an improvement, where they have to strike at all on large bells. Such clocks hardly ever bring the full sound out of the bells ; because, in order to do so, the weights would have to be so heavy, and the clock so large, as to increase the price considerably. A good bell, even of the ordinary thickness, which is less than in the Westminster bells, requires a hammer of not less than ^th of its weight, rising 8 or 9 inches from the bell, to bring out the full sound ; and therefore, allowing for the loss by friction, a bell of 30 cwt, which is not an uncommon tenor for a large peal, would require a clock weight of 15 cwt., with a clear fall of 40 feet ; and either the Cambridge quarters on a peal of ten, or the Doncaster ones on the 2d, 3d, 4th, and 7th bells of a peal of eight, will require above a ton, according to the usual scale of bells in a ring ing peal (which is thinner than the Westminster clock bells). Very few clocks are adapted for such weights as these ; and without abundance of strength and great size in all the parts, it would be unsafe to use them. But if the striking parts are made to wind up every day, of course }th of these weights will do ; and you may have a more powerful clock in effect, and a safer one to manage, in half the com pass, and for much less cost. Churches with such bells as these have always a sexton or some other person belonging to them, and in attendance every day, who can wind up the clock just as well as a clockmaker s man, The going part always requires a much lighter weight, and may as well go a week, and be in the charge of a clock- maker, where it is possible.
There should be some provision for holding the hammers off the bells while ringing, and at the same time a friction-spring or weight should be brought to bear on the fly arbor, to compensate for the removal of the weight of the hammers ; otherwise there is a risk of the train running too fast and being broken when it is stopped.
No particular number of cams is required in the striking wheel ; any number from 10 to 20 will do ; but when four quarters on two bells are used, the quarter-striking wheel should have half as many cams again as the hour-wheel ; for, if not, the rope will go a second time over half of the ban-el, as there are 120 blows on each quarter bell in the 12 hours to 78 of the hours, while with the three quarters there are only 72. If the two quarter levers are on the same arbor, there must be two sets of cams, one on each side of the wheel ; but one set will do, and the same wheel as the hour- wheel, if they are placed as in fig. 23. The hour-striking lever, it will be seen, is differently shaped, so as to diminish the pressure on its arbor by making it only the difference, instead of the sum, of the pressures.at the two points of action. This can be done with the two quarter levers, as shown in the Rudimentary Treatise; but the arrangement involves a good deal of extra work, and as the quarter hammers are always lighter than the hour one, it is hardly worth while to resort to it. The shape of the cams is a matter requiring some attention, but it will be more properly considered when we come to the teeth of wheels. The 4th quarter bell in the Cambridge and Westminster quarters should have two hammers and sets of cams longer than the others, acting alternately, on account of the quick repetition of the blows.
The fly ratchets should not be made of cast-iron, as they some times are by clockmakers who will not use cast-iron wheels on any account, because the teeth get broken off by the click. This break ing may perhaps be avoided by making the teeth rectangular, like a number of inverted V s set round a circle, and the click only reach ing so far that the face of the tooth which it touches is at right angles to the click ; but, as before observed, cast-iron and steel do not work well together.
The hammer of a large clock ought to be left " on the lift," when the clock has done striking, if the first blow is to be struck exactly at the hour, as there are always a good many seconds lost in the train getting into action and raising the hammer. Moreover, when it stops on the lift, the pressure on the stops, and on all the pinions above the great wheel, is only that due to the excess of the power of the clock over the weight of the hammer, and not the full force of the weight, and it is therefore easier for the going part to discharge, and less likely to break the stops.
In fig. 22 the wheel marked 60 in each of the striking parts is a winding wheel on the front end of the barrel, and the winding pinion is numbered 10 ; a larger pinion will do where the hammer does not exceed 40 ft ; and in small clocks no auxiliary winding wheel is needed. But in that case the locking-plate must be driven by a gathering pallet, or pinion with two teeth, on the arbor of the second wheel, with a spring click to keep it steady. In all cases the hammer shanks and tails should not be less than two feet long, if possible ; for the shorter they are, the more is lost by the change of inclination for any given rise from the bell. In some clocks with fixed (not swinging) bells, the hammer-head is set on a double shank embracing the bell, with the pivots, not above it in the French way, which makes the hammer strike at a wrong angle, but on each side of the bell, a little below the top. On this plan less of the rise is lost than in the common mode of fixing. The Westminster clock hammers are all fixed in this way.
The first thing to remark in the going part of fig. 22 is that the hour-wheel which carries the snails for letting off the quarters and striking, is not part of the train leading up to the scape-wheel, but independent, so that the train from the great wheel to the scape- v/heel, is one of three wheels only. If it were a dead escapement, instead of a gravity escapement clock, the wheel numbered 96 would be the scape-wheel ; and as it turns in 90 seconds, it would require 36 teeth or pins for a 1J sec. pendulum which most of these gravity -escapement clocks have ; it is about 6 feet long to the bottom of the bob, which, if sunk just below the floor, brings the clock-frame to a very convenient height. The hour-wheel rides loose on its arbor, or rather the arbor can turn within it, carrying the snails and the regulating hand and the bevelled wheel which drives all the dials, and it is fixed to the hour-wheel by means oi clamping screws on the edge of a round plate on the arbor just behind it, which turn by hand. In a gravity escapement clock this adjusting work is not really necessary ; because you can set the clock by merely lifting the pallets oli the scape-wheel, and letting the train run till the hands point right. The regulating hand, you observe, in fig. 22 turns the wrong way; because, where the dial is opposite to the back of the clock, no bevelled wheels are wanted, and the arbor leads straight off to the dial. It used to be the fashion to put clocks in the middle of the room, so that the leading- off rod might go straight up to the horizontal bevelled wheel in the middle, which drove all the dials. But the clock can be set much more firmly on stone corbels, or on cast-iron brackets built into the wall; and it is not at all necessary for the leading-off rod to be vertical. Provided it is only in a vertical plane parallel to the wall, or the teeth of the bevelled wheels adapted to the inclination, the rod may stand as obliquely as you please ; and when it does, it ought on no account to be made, as it generally is, with universal joints, but the pivots shouldgo into oblique pivot-holes at the top and bottom. The joints increase the friction considerably, and are of no use whatever, except where the rod is too long to keep itself straight. Where the rod does happen to be in the middle of the room, and there are three or four dials, the two horizontal bevelled wheels at each end of it must be a little larger than all the others both the one in the clock and those of the dial-work ; for otherwise the three or four wheels in the middle will meet each other and stick fast.
When the pendulum is very long and heavy, it should be sus pended from the -wall, unless the clock-frame has some strong support near the middle ; but a six-feet pendulum, of not more than two cwt., may be suspended from the clock-frame, provided it is as strong as it ought to be for the general construction of the clock, and supported on corbels or iron beams. It has generally been the practice to hang the pendulum behind the clock-frame ; but inasmuch as the rope of the going part may always be thinner than that of the striking part, and that part requires less depth in other respects, a different and more compact plan is adopted in the clocks we are describing. The back pivots of the going wheels run in bushes in an intermediate bar, three or four inches from the back of the frame, joining the two cross bars, of which the ends are dotted in the drawing. The pendulum cock is set on the back frame, and the pendulum hangs within it. And in the gravity escapement clocks there is yet another thin bar about half way between the back frame and the bar on which the bushes of the wheels are set the only use of which is to carry the bush of the scape-wheel, which is set behind the fly; the wheel, the fly, and the pallets, or gravity- arms, stand between these two intermediate bars ; and the pallet- arbors are set in a brass cock screwed to the top of the pendulum- cock. The beat-pins should be of brass, not steel, and no oil put to them, or they are sure to stick. The escapement in fig. 22 is not drawn rightly for the present form of them, which is given hi fig. 13.
The same gen.eral arrangement will serve for a dead escapement
