<p>
	The chronometer from the Greek &quot;chronos&quot;(time) and the Latin &quot;metrum&quot; (to measure) is a navigational instrument used to determine longitude.&nbsp; It was invented in the early 18th C and was essential to navigation until radiotelegraphy was invented in the 20th C.&nbsp; Despite the use of GSN-GPS at the end of the 20th C its presence on board is still obligatory.&nbsp;<br />
	The 19th C chronometer in its round brass case and its mahogany box is highly prized by collectors</p>