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, which served as a prototype of the marine sextant still used today. Seven Years War Campbell, meanwhile, returned to Royal George as flag captain in November 1759, this time under Hawke (when Hawke moved his flag to that ship), serving as such during the decisive battle of Quiberon Bay on 20 November 1759. It was Campbell whom Hawke sent to England on 24 November in the frigate Vengeance with news of the victory, and after a six-day voyage Campbell, accompanied by Lord Anson (now First Lord of the Admiralty), personally gave the king the news. Next, Campbell was captain of Dorsetshire (70 guns), on the home station and in the Mediterranean, from 1760 to the