His father died in 1744 bequeathing to James 14,300 acres (and making smaller bequests to the two younger sons William and Henry).

He embarked on a continental Grand Tour to Paris then Rome, meeting more Jacobite sympathisers along with the experienced traveller Robert Wood.

On 5 May 1750, Wood, Dawkins, Dawkins' Oxford friend John Bouverie and the Italian draughtsman Giovanni Borra set off from Naples in the Matilda to tour and study the Aegean, the coast of Anatolia, Egypt, Nazareth, Syria (including the ruins of Palmyra and Baalbek), Tripoli and Cyprus, returning in Naples on 7 June 1751.

The British government issued a warrant for Dawkins's arrest in retaliation, but it was not put into effect when he returned to England in 1754.

The anonymous 1756 pamphlet, Reflections physical and moral upon the ... numerous phenomena ... which have happened from the earthquake at Lima, attributed to Dawkins, shows his philosophy to have been opposed to that of Rene Descartes and Isaac Newton.