french silver 35mm medal great inventions england John Harrison marine chronomet

Description

12grs approx, in very fine condition as scanned,rim nicks, mintmarks on edge
John Harrison
(3 April [
O.S.
24 March] 1693 – 24 March 1776) was a self-educated English
carpenter
and
clockmaker
who invented the
marine chronometer
, a long-sought-after device for solving the
problem of calculating longitude
while at sea.