Between 1586 and 1588, Hues travelled with Thomas Cavendish on a circumnavigation of the globe, performing astronomical observations and taking the latitudes of places they visited.

[6] According to the Oxford Dictionary of National Biography, there is unsubstantiated evidence that after completing his degree Hues was held in the Tower of London, though no reason is given for this, then went abroad after his release.

[9] Hues became interested in geography and mathematics – an undated source indicates that he disputed accepted values of variations of the compass after making observations off the Newfoundland coast.

He either went there on a fishing trip, or may have joined a 1585 voyage to Virginia arranged by Raleigh and led by Richard Grenville, which passed Newfoundland on the return journey to England.

An anonymous 17th-century manuscript states that Hues circumnavigated the world with Cavendish between 1586 and 1588 "purposely for taking the true Latitude of places";[11] he may have been the "NH" who wrote a brief account of the voyage that was published by Hakluyt in his 1589 work The Principall Navigations, Voiages, and Discoveries of the English Nation.

[12] In the year that book appeared, Hues was with Edward Wright on the Earl of Cumberland's raiding expedition to the Azores to capture Spanish galleons.

[13] In the meantime, delayed in small harbours in the Strait with crew members dying from the cold, illness and starvation, Cavendish turned back eastwards to return to England.

He returned to England after Cavendish died,[15] and published his discoveries in the work Tractatus de globis et eorum usu (Treatise on Globes and Their Use, 1594),[16] which he dedicated to Raleigh.

[17] Apparently, the book was also intended to encourage English sailors to use practical astronomical navigation,[1] although Lesley Cormack has observed that the fact it was written in Latin suggests that it was aimed at scholarly readers on the Continent.

[22] Tractatus de globis begins with a letter by Hues dedicated to Raleigh that recalled geographical discoveries made by Englishmen during Elizabeth I's reign.

[26][28] In the work, Hues also published for the first time the six fundamental navigational propositions involved in solving what was later termed the "nautical triangle" used for plane sailing.

For participating in the Bye Plot, a conspiracy by Roman Catholic priest William Watson to kidnap James I and force him to repeal anti-Catholic legislation, Grey was attainted and forfeited his title in 1603.

[31] Together with the scientist Nathanael Toporley and the mathematician Thomas Allen, the men kept abreast of developments in astronomy, mathematics, physiology and the physical sciences, and made important contributions in these areas.

[32] According to the letter writer John Chamberlain, Northumberland refused a pardon offered to him in 1617, preferring to remain with Harriot, Hues and Warner.

[33] However, the fact that these companions of Northumberland were his "Three Magi" studying with him in the Tower of London has been regarded as a romanticisation by the antiquarian John Aubrey and disputed for lack of evidence.

Quo defuncto, ad studia henrici Comitis Northumbriensis ibidem vocatus est, cujus filio instruendo cum aliquot annorum operam in hac Ecclesia dedisset et Academiae confinium locum valetudinariae senectuti commodum censuisset; in ædibus Johannis Smith, corpore exhaustus, sed animo vividus, expiravit die Maii 24, anno reparatae salutis 1632, aetatis suæ 79.

[37] [Here lies a highly lettered man, of the highest moral and religious integrity, Robert Hues, on account of his erudition in all subjects, both Theology and History, and Rhetoric, Philology, and Philosophy, but especially Mathematics (of which a notable volume [i.e., his book] remains in print).