Early life John Campbell was born in the parish of Kirkbean, Scotland. His father, John Campbell (died 1733), was
minister of Kirkbean and John was at an early age apprenticed to the master of a coasting vessel. That vessel's mate was pressed into the navy, and John is said to have entered the navy by offering himself in exchange for him. He served for three years in
Blenheim,
Torbay, and
Russell before being appointed in 1740 as a midshipman to
Centurion. On
Centurion's ensuing
circumnavigation of the world as the flagship of
Commodore George Anson, he was promoted
master's mate when a vacancy came up soon after sailing, and was promoted to
master after the 1743 engagement against the Manila galleon
Nuestra Señora de Covadonga. One of his fellow midshipmen was
Augustus Keppel, who from then on became a lifelong friend. He was married, but his wife's name is not known. Returning home in early January 1745, Campbell passed the examination for lieutenant on 16 January 1745, and with Anson's influence behind him, he was promoted to
commander on 27 May 1747, The
astronomer royal,
James Bradley, was shown Campbell's results and found them to correspond exactly with the actual distances in the sky, and Bradley and Campbell together made frequent observations at
Greenwich of the Moon's distance from the Sun and stars, and of the stars' distances from one another. His next commands after
Bellona were
Mermaid,
Prince (
90 guns) and – in 1757 –
Essex (
64 guns) under
Edward Hawke in the
Bay of Biscay and the blockade of Brest (barring an interlude in 1758/59, as flag captain to Anson in
Royal George when he temporarily took over command of the Brest fleet). During Campbell's command of
Essex, in 1756, James Bradley suggested to the
Board of Longitude (chaired by Anson) that Campbell should give a sea trial to
Tobias Mayer's new
lunar tables and
reflecting circle, and Campbell did so successfully within sight of the French coast, 'though they [the observations] were not taken with all the advantages that might have attended them, had I been alone; for I was all the cruise in company with an admiral whose motions I was obliged to follow', in trials which would profoundly influence marine navigation for the next 250 years. He compared Mayer's new reflecting circle instrument with the common wooden
Hadley octant as means of observing lunar distances, and in doing so found Mayer's was much too heavy whereas Hadley's – though it could not measure angles beyond 90° and was often unstable in its wooden frame – was far more useful. From this, he suggested modifications to the Hadley octant, extending its arc from 45° to 60° (to allow the measurement of arcs up to 120°) and making it of brass not wood. In 1759
John Bird, commissioned by the Board of Longitude, produced an instrument taking up both suggestions, a sextant of 20 inches radius with a brass frame and 1/3 the weight of the reflecting circle, Campbell held the governorship from 1782 to his death in London in 1790. During this time he returned to Britain periodically, allowing him in 1784 and 1785 – at
Hans Moritz von Brühl's request – to arrange trials of
Thomas Mudge's first chronometer on his passage to and from Britain and in Newfoundland (borrowing an achromatic telescope from the Board of Longitude to ascertain Newfoundland's longitude). Also, as a result of Campbell's proclamation of religious freedom for all inhabitants of Newfoundland,
Bishop James Louis O'Donel authorised the construction of a Catholic church. Campbell was promoted to
vice-admiral of the white on 24 September 1787. == In popular media ==