Most high quality mantel clocks are driven by means of a pendulum, which was the norm for clocks from the seventeenth century until the advent of electric clocks in the 1930s. Pendulum-driven clocks are very sensitive so care has to be taken when adjusting the pendulum, though periodic adjustment is necessary for the mechanism to maintain proper time.
The first step, before the clock is running is to set the time. Though your can set the time once the clock is running, it is usually safer to do so when the clock is still as this minimizes the chances of accidently affecting the mechanism. You should probably set the clock back by a few minutes so that you can fine tune the setting by pushing the minute hand forward (clockwise) just a bit once the clock is running. You should always try to set the clock by the minute hand, leaving the hour and second hands alone as much as possible.
Next you must get the pendulum running. First wind the clock. Most pendulum clocks have to be wound before they will run at all. Once the clock is wound you can either light push the pendulum from side to side or you can tip the clock lightly from side to side. Either method should get the pendulum to begin swinging. If the pendulum fails to start then theree is probably a problem with your clock and you should consult with a trained clock repair person or restorer.
Once your clock is running, you can fine tune the time setting using a digital or electric clock by determining whether or not the clock is running correctly. If it is running extremely fast or slow, this should be readily evident within an hour or so. More often, the discrepancy is smaller and harder to notice, so you should probably monitor the clocks progress against your electric or digital clock over a period of a few hours. Chances are your clock will need an adjustment.
The basic rule of thumb to follow when setting a pendulum is that the longer the pendulum is, the slower it runs and the opposite is also true. If your clock is running fast, you will need to lower the pendulum bob; if it is running slow, you will need to raise it. As this is a normal part of owning and operating a pendulum clock, virtually all pendulum clocks make this process fairly easy to accomplish.
Most modern pendulum clocks have a nut or disk at the bottom of the pendulum bob that can be turned. Turning it to the left lowers the bob, lengthening the pendulum and thus slowing the clock, with the opposite being true if you turn it to the right. Some older clocks, especially antique clocks from the 1920s and earlier, have more complex mechanisms for accomplishing the same thing, but most are fairly obvious and user-friendly. Some rare clocks, however, require a special key to make this adjustment and if the key has been lost it is probably worth the time to consult with a professional clock expert as opposed to risking damaging the clock.
Tags: adjustment, clock, electric clocks, mantel clocks, mechanism, pendulum, proper time, seventeenth century, side