1. The Literal Sense:
* Clocks and Watches: The most common usage of "second hand" refers to the hand on a clock or watch that indicates seconds. This usage is very old, dating back to the development of clocks and watches with second hands.
* Mechanics: The term "second hand" also appears in mechanics to describe parts of a machine that are not in direct contact with the power source but instead receive motion from a primary moving part. This refers to the way the second hand on a clock is indirectly powered by the other hands.
2. The Figurative Sense:
* Pre-Owned Goods: The use of "second hand" to describe something previously owned by someone else is a figurative extension of the literal meaning. Imagine a clock: its second hand is the last part to move after the others, similar to how a second-hand item is the last part of its lifespan in the original owner's possession. This usage emerged in the 1800s.
3. Evolution of Language:
* "Second-hand" vs "Used": The phrase "second hand" gradually became more associated with the idea of pre-owned goods. While "used" is now a more common term for this, "second hand" remains in use, particularly in certain contexts like antique shops or vintage clothing stores.
In Summary:
The phrase "second hand" has roots in the literal sense of clock mechanisms and mechanical systems. Its figurative extension to pre-owned goods reflects a metaphorical comparison to how the second hand on a clock receives its motion from a primary source. This usage has persisted, though "used" has become more widespread in modern English.