When did the following event happen?
The UK officially adopts the Union Jack as its national flag.
Select a space in the timeline below.
1757
John Campbell invents the sextant to enable sailors to measure the angle between an astronomical object and the horizon for the purposes of celestial navigation.
Note:
BCE means that the date is the number of years before the current era (CE/AD).
c. is short for 'circa' and indicates that the date is considered approximate.