Why does a Watch Need a Second Hand?

A useful feature of the second hand is to know the watch is still running.

A wall clock, desk clock or watch has 3 basic hands. These are the hour, minute and second hands. But when we check time, we only need the hour and minute hands. So what is the second hand appearing on the dial for? Do we let our free time have nothing to do, can we sit and watch time slowly pass in vain?

In fact, the second hand is not so essential on the dial, but not useless either. And the second hand also has a pretty heroic history and a great deal of responsibility, which many of us may not even know.

When did the second hand appear?

The seconds hand is actually a later innovation on modern timepieces, but they have appeared from the 15th century. Although, at the time, the seconds hand was still uncommon. This is partly due to user’s needs and partly due to technology.

The second hand first appeared in the 15th century on pocket watches made in Germany. At that time, the second hand was mainly used for specialized watches, rather than for conventional watches.

With conventional watches, the second hands had no practical effect and were also difficult to manufacture. Until the 17th century, watchmakers added a “4th wheel” to a standard 3-wheel movement, with a rotation period of exactly 1 minute.

Then, this 4th gear is combined with an external gear, responsible for stop time. Since then, it has become simpler for the manufacturers to add an extra dial and second hand to the watch, and also more common.

In the 19th century, the second hand and seconds sub dial became popular. It was not until the 20th century that the second hand was introduced into the center, on the same axis and dial as the minute and hour hands. However, the second hand was still considered only a subset of the powertrain inside the watch.