Page:Encyclopædia Britannica, Ninth Edition, v. 6.djvu/35

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CLOCKS
25

however, be mentioned here that the earliest form in which a spring seems to have been used was not that of a spiral rib bon of steel rolled up, but a straight stiff spring held fast to the clock frame at one end, and a string from the other end going round the barrel, which was wound up ; but such a spring would have a very small range. Spring clocks are generally resorted to for the purpose of saving length ; for as clocks are generally made in England, it is impossible to make a weight-clock capable of going a week, without either a case nearly 4 feet high, or else the weights so heavy as to produce a great pressure and friction on the arbor of the great wheel. But this arises from nothing but the heavi ness of the wheels and the badness of the pinions used in most English clocks, as is amply proved by the fact that the American and Austrian clocks go a week with smaller weights and much less fall for them than the English ones, and the American ones with no assistance from fine work manship for the purpose of diminishing friction, as they are remarkable for their want of what is called "finish" in the machinery, on which so much time and money is wasted in English clock-work.

All the ornamental French clocks, and all the short " dials," as those clocks are called which look no larger than the dial, or very little, and many of the American clocks, are made with springs. Indeed we might omit the word "French" after "ornamental;" for the manufacture of ornamental clocks has practically ceased in England, anil we are losing more of all branches of the horological trade yearly, as w r e are unable, i.e., our workmen do not choose, to compete with the cheaper labour of the Continent, or with the much more systematic manufacture of clocks and watches by machinery in America than exists here, though labour there is much dearer. It is true that most of the American clocks are very bad, indeed no better than the old-fashioned Dutch clocks (really German) made most ingeniously of wood and wire, besides the wheels. But some better American ones are also made now, and they will no doubt improve as their machine made watches have done. Though this has been going on now for 30 years and more, no steps appear to have been taken to establish anything of the kind in this country, except that watch " movements," which means only the wheels set in the frame, are to a certain extent made by machinery in Lancashire and Coventry for the trade, who finish them in London and elsewhere. That is the real meaning of the advertisements of "machine-made watches" here.

The French clocks have also been greatly improved within the same time, and are now, at least some of them, quite different both in construction and execution from the old-fashioned French drawing-room clock which generally goes worse than the cheapest "Dutchman," and is nearly always striking wrong, because they have the locking-plate striking work, which if once let to strike wrong, either by altering the hands or letting it run down, cannot be set right again except by striking the hours all round, which few people know how to do, even if they can get their fingers in behind the clock to do it, .The Americans have a slight wire hanging down a little below the dial which you can push up and so make the clock strike. All locking- plate clocks ought to have a similar provision.

There is not much use in having clocks to go more than a little over eight days (to allow the possible forgetting of a day), as a week is the easiest period to remember. The French spring-clocks generally go a fortnight, but most people wind them up weekly. Occasionally English clocks are made to go a month by adding another wheel ; and even a year by adding two. But in the latter case it is better to have two barrels and great wheels acting on opposite sides of a very strong pinion between them, as it both reduces the strain on the teeth and the friction of the pivot of that pinion. Such clocks sometimes liave a 5 feet or l sec. pendulum, as the case must be a tall one. The great thing is to make the scape-wheel light, and even then you can never get more than a small arc of vibration, which is undesirable for the reason given above, and such a long train is peculiarly sensitive to friction.

In the American clocks the pinions are all of the kind called lantern pinions, which have their leaves made only of bits of wire set round the axis in two collars ; and, oddly enough, they are the oldest form of pinion, as well as the best, acting with the least friction, and requiring the Last accuracy in the wheels, but now universally disused in all English and French house clocks. The American clocks prove that they are not too expensive to be used with advantage when properly made ; although, so long as there are no manufactories of clocks here as there are in America, it may be cheaper to make pinions in the slovenly way of cutting off all the ribs of a piece of pinion wire, so as to reduce it to a pinion a quarter of an inch wide, and an arbor 2 or 3 inches long. On the whole, the common English house clocks, so far from having improved with the general progress of machinery, are worse than they were fifty years ago, and at the same time are of such a price that they are being fast driven out of the market by the American plain clocks and by the French and German ornamental ones.

Clocks have been contrived to wind themselves up by the alternate expansion and contraction of mercury and other fluids, under variations of temperature. Wind-mill decks might be made still more easily, the wind winding up a weight occasionally. Water-clocks have also been made, not on the clepsydra principle, where the flow of the water determined the time very inaccurately ; but the water is merely the weight, flowing from a tap into a hollow hori zontal axis, and thence by branches into buckets, which empty themselves as they pass the lowest point of the circle in which they move, or flowing directly into buckets, so emptying themselves. But the slopping of the water, and the rusting of any parts made of iron, and the cost of the water itself always running, destroy all chance of such things coming into use.


Electrical Clocks.


It should be understood that under this term two, or wo may say three, very different things are comprehended. The first is a mere clock movement, i.e., the works of a clock without either weight or pendulum, which is kept going by electrical connection with some other clock of any kind (these ought to be called electrical dials, not clocks) ; the second is a clock with a weight, but with the escape ment worked by electrical connection with another clock instead of by a pendulum ; and the third alone are truly electrical clocks, the motive power being electricity instead of gravity; for although they have a pendulum, which of course swings by the action of gravity, yet the requisite impulse for maintaining its vibrations against friction and resistance of the air is supplied by a galvanic battery, instead of by the winding up of a weight.

If you take the weight off a common recoil escapement

clock, and work the pallets backward and forwards by hand, you will drive the hands round, only the wrong way ; consequently, if the escapement is reversed, and the pallets are driven by magnets alternatively made and unmade, by the well-known method of sending an electrical current through a wire coil set round a bar of soft iron, the contact being made at every beat of the pendulum of a standard clock, the clock without the weight will evidently keep exact time with the standard clock ; and the only question

is as to the best mode of making the contact, which is not