applied to it, and nouc but actual use for a considerable time would be of mucLi value.
The Westminster Clock.
It is unnecessary to repeat the account of the long dispute between the Government, the architect of the House of Parliament, the astronomer royal, Sir E. Beckett, and some of the London clock- makers, which ended in the employment of the late E. J. Dent and his successor F. Dent from the designs and under the superintend ence of Sir E. Beckett, as the inscription on it records The fullest account of these was given in the 4th and 5th editions of the Treatise on Clocks, and we shall now only describe its construction. Fi". 27 is a front elevation or section lengthwise of the clock, The frame is 16 feet long and 5? wide, and it rests on two iron plates lying on the top of the walls of the shaft near the middle of the tower, down which the weights descend. That wall reaches up to the bell chamber, and those iron plates are built right through it, and so is the great cock which carries the pendulum. The clock- room is 28 feet x 19, the remaining 9 of the square being occupied by the staircase and an air-shaft for ventilating the whole building. The going part of the clock, however, not requiring such a long barrel as the striking parts, which have steel wire ropes 55 inch thick, is shorter than they are, and is carried by an intermediate bar or frame bolted to the cross bars of the principal frame. The back of them is about 2^ feet from the wall, to leave room for a man behind, and the pendulum cock is so made as to let his head come within it in order to look square at the escapement. The escape ment is the double three legs (fig. 13), and the length of the teeth or legs is 6 inches. The drawing represents the wheels (except the Welled wheels leading off to the dials) as mere circles to prevent confusion. The numbers of teeth and the time of revolution of the principal ones are inserted and require no further notice. Their size can be taken from the scale ; the great wheels of the striking parts are 2
The maintaining power for keeping the clock going while winding is peculiar and probably unique. None of those already described could have kept in gear long enough, maintaining sufficient force all the time, as that part takes 10 minutes to wind, even if the man does not loiter over it. This is managed without a single extra wheel beyond the ordinary winding pinion of large clocks. The winding wheel on the end of the barrel is close to the great wheel, and you see the pinion with the winding arbor in the oblique piece of the front frame of the clock. Consequently that arbor is about 6 feet long, and a little movement of its back end makes no material obliquity in the two bushes ; i.e., it may go a little out of parallel with all the other arbors in the clock without any impediment to its action. Its back pivot is carried, not in a fixed bush, but in the lower end of a bar a little longer thanthe great wheel s radius, hang ing from the back of the great arbor ; and that bar has a spring click upon it which takes into ratchet teeth cast on the back of the great wheel. When the great wheel is turning, and you are not winding, the ratchets pass the click as usual, but as soon as you begin to wind the back end of the winding arbor would rise but for the click catching those teeth, and so the great wheel itself become the fulcrum for winding for the time. After the winding has gone a few minutes a long tooth projecting from the back of the arbor catches against a stop, because that end of the hanging bar and pinion have all risen a little with the motion of the great wheel. Then the man is obliged to turn the handle back a little, which lets down the pinion, &c., and the click takes up some lower teeth ; and so if he chooses to loiter an hour over the winding he can do no harm. The winding pinion "pumps" into gear and out again as usual. The going part will go Si days, to provide for the possible forgetting of a day in winding. The weight is about 160 K ; but only one-14th of the whole force of that weight is requisite to drive the pendulum, as was found by trial ; the rest goes in overcoming the friction of all the machinery, including a ton and a half of hands and counterpoises, and in providing force enough to drive them through all weathers, except heavy snows, which occasionally accumu late thick enough on several minute hands at once, on the left side of the dials, to stop the clock, those hands being 11 feet long. For the dials are 22 feet in diameter, or contain 400 square feet each, and there are very few rooms where such a dial could be painted on the floor. They are made of iron framing rilled in with opal glass. Each minute is 14 inches wide. The only larger dial in the world is in Mechlin church, which is 40 feet wide ; but it has no minute hand, which makes an enormous difference in the force required in the clock. They are completely walled off from the clock-room by a passage all round, and there are a multitude of gas lights behind them, which are lighted by hand, though provision was originally made in the clock for doing it automatically. The hour hands go so slow that their weight is immaterial, and were left as they were made of gun metal under the- architect s direction but it was impossible to have minute hands of that construction and weight without injury to the clock, and so they were removed by Sir E. Beckett, and others made of copper tubes, with a section com posed of two circular arcs put together, and are consequently very stiff, while weighing only 28 lt>. The great weight is in the wheels, tubes, and counterpoises. The minute hands are partly counterpoised i-.utside, making their total length 14 feet, to relieve the strain upon their arbors. They all run on friction wheels imbedded in the larger tubes 5k inches wide, which carry the hour hands, which themselves run on fixed friction wheels.
Fig. 27.—Section of Westminster Clock.
There is nothing peculiar in the quarter striking part except its size, and perhaps in the barrel turning in an hour and a half, i.e., iu three repetitions of the five chimes already described. The cams are of wrought iron with hard steel faces. Each bell has two hammers, which enables the cams to be longer and the pressure on them less. The hour-striking wheel has ten cams 24 in. wide cast on it ; but those cams have solid steel faces screwed on them. All this work was made for a hammer of 7 cwt., lifted 13 inches from the bell, i.e., about 9 inches of vertical lift. The hammer was reduced to K cwt. after the partial cracking of the bell. The rod from the lever to the hammer is made of the same wire rope as the weight ropes, and the result is that there is no noise in the room while the clock is strik ing. The lever is 5 feet 4 inches long, and strikes against the buffer spring shown in the drawing, to prevent concussion on the clock-frame, of which you cannot feel the least. The quarter ham mer levers have smaller springs for the same purpose, and the stops of the striking part are also set on springs instead of rigid as usual. The ilies, for which there was not room in the drawing, are near the top of the room and are each 2 feet 4 inches square. They make a considerable wind in the room when revolv ing. The only noise made in striking is their running on over their ratchets when the striking stops. Each striking weight is a ton and a half or was before the great hammer was reduced. They take 5 hours to wind up, and it has to be done twice a week, which was thought better than making the parts larger and the teeth more numerous and the weights twice as much, to go a week, and of course the winding must have taken twice as long, as it was adapted to what a man can do continuously for some hours. Con- sequently it was necessary to contrive something to stop the man.
