The invention of the first chronometer is often attributed to John Harrison, an English clockmaker. While it's not entirely accurate to say he invented the first chronometer, his work was pivotal in developing the first accurate and reliable marine chronometer.

Here's why:

* Prior to Harrison's work: There were attempts to create timekeeping devices for navigation, but they were inaccurate and unreliable.

* Harrison's contributions: He spent decades developing a series of increasingly precise timepieces, culminating in his H4 chronometer in 1761. This device proved incredibly accurate, keeping time within a few seconds per day, a remarkable feat for the time.

* The "Marine Chronometer": While Harrison's H4 was a monumental achievement, the term "chronometer" itself was not widely used until later. The term was coined in the 18th century, and it was used to describe any high-precision timekeeping device, not just Harrison's work.

So, while John Harrison's work is undeniably significant, the term "chronometer" didn't exist during his lifetime. However, his H4 chronometer is widely recognized as the first truly reliable and accurate timekeeping device for navigation at sea.