Page:Popular Science Monthly Volume 26.djvu/685

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THE ACCURATE MEASUREMENT OF TIME.
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The second class of escapements which we shall find exampled in the waste-box is called the cylinder escapement, which still continues to be used in some of the cheaper Swiss movements in boys' watches, and such as the ladies wear suspended from the belt. It is the most compact escapement which has ever been made, and is employed in such very small specimens of the watch kind as are made to be set in the head of a pencil, a shirt-stud, etc. It is by far the most reliable escapement except the lever. Its principle is that the cylinder of the balance-wheel is so cut that each tooth of the scape-wheel must force it partly round to get past it. While it is making this turn, the next tooth of the scape-wheel is caught upon the blank side of the cylinder, and held until the recoil of the hair-spring brings the balance back.

Here and there a specimen is to be found of the old "duplex" escapement to which the modern "Waterbury" is allied. It is so rare as hardly to need our consideration. It is a good escapement when in order, but is rather liable to get out of order.

A third form of escapement, and the one now in use almost universally, is the detached lever. There are patent levers, straight-line levers, and various other levers, but they are all detached levers, for the reason that there is one point, in the course of each swing of the balance, when the lever is entirely free or detached from the balance-wheel, and so stands until the return-swing unlocks it. It is difficult to conceive of anything that would be an improvement upon this, and seemingly no improvement is needed.

Before we pass from the consideration of the escapement to that of the balance itself, a remark should be made as to the relative advantages of different rates of escapement. It is found that up to a certain point what is called the quickness of the train, or, in plain English, the rapidity with which a watch beats, makes a difference with its qualities as a time-keeper. This seems to be owing to the fact that where a watch beats more slowly it is more apt to lose an occasional beat through the jar and tossing about in the pocket. The Swiss manufacturers took the lead, and have for forty years or more made quick-train watches, beating five times to the second, or eighteen thousand times to the hour. The English watches commonly beat four times to the second, or fourteen thousand four hundred to the hour. American watches are made with the quick train of the Swiss, but more commonly with a beat intermediate between the two extremes. It is curious that the English, who have given so much money and thought in the past to the manufacture of time-pieces, do not to-day make a good watch nor a good common clock. Their adherence to the slow train is one of the reasons of their failure in watches, and their retention of the fusee is another. So great has been the decline in the English trade in watches and clocks, that a number of their experts in that line recently recommended petitioning the Government to cause an official investiga-