On the 27th of October, after having taken an active part, in the council s of the sovereign, and effected several cures of persons about the court attacked with the small-pox, he left the capital, and set out in search of the source of the Nile, which he discovered at Saccala, on the 14th of the following November. The joy he felt on the occasion is thus described by himself: 'It is easier to guess than to describe the situation of my mind at that moment standing in that spot which had baffled the genuis, history, and inquiry of both ancients and moderns, for the course of nearly three thousand years. Kings had attempted this discovery at the head of armies, and each expedition was distinguished from the last only by the difference of the numbers which had perished, and agreed alone in the disappointment which had uniformly, and without exception, followed them all. Fame, riches, and honor, had been held out, for a series of ages, to every individual of the myriads those princes commanded, without having produced one man capable of gratifying the curiosity of his sovereign, or wiping off the stain upon the enterprise and abilities of mankind, or adding this desideratum for the encouragement of geography. Though a mere private Briton, I triumphed here in my own mind over kings and their armies; and every comparison was leading the nearer to presumption, when the place itself where I stood, the object of my vain glory, suggested what depressed my short-lived triumphs. I was but a few minutes arrived at the source of the Nile, though numberless dangers and sufferings, the least of which would have overwhelmed me, but for the continual goodness and protection of Providence; I was, however, then but half through my journey, and all those dan g ers which I had already passed, awaited me again on my return. I found a despondency gaining ground fast upon me, and blasting the crown of laurels I had too rashly woven for myself.'
After returning to Gondar, our traveler found much difficulty in obtaining permission to proceed on his way homewards; it being a rule with the inhabitants never to allow a stranger to quit Abyssinia. A civil war breaking out in the country about the period of his intended departure, he was compelled to remain in it till the December of the following year, and took part in one of their battles, in which his valiant conduct was such that the king presented him with a rich suit of apparel, and a gold chain of immense value. At length, at the end of 1771, he set out from Gondar, and in the February of the following year, arrived at Senaar, where he remained two months, suffering under the most inhospitable treatment, and deceived in his supplies of money which compelled him to sell the gold chain he had been presented with. He then proceeded by Chiendi, and Gooz, through the Nubian desert, and on the 29th of November, reached Assouan, on the Nile, after a most dreadful and dangerous journey, in the course of which he lost all his camels and baggage, and twice laid himself down in the expectation of death. Having procured, however, fresh camels, he returned to the desert and recovered most part of his baggage, with which, on the 10th of January, he arrived at Cairo: where, ingratiating himself with the bey, he obtained permission for English commanders to ingratiating their vessels and merchandise to Suez, as well as to Jidda, an advantage no other European nation had before been able to acquire. In the beginning of March he arrived at Alexandria, whence he sailed to Marseilles; where he landed about the end of the month, suffering under great agony from a disease called the Guinea worm, which totally disabled him from walking, and had nearly proved fatal to him during his voyage. Notwithstanding, however, the perils he underwent, and the barbarities he witnessed in the course of his travels, and particularly at Abyssinia, yet even that country he left with some regret, and would often recall, with a feeling almost of tenderness, the kindnesses he had received there, especially from the ras's wife, Ozoro Esther, between himself and whom a very affectionate intimacy had existed.
After residing a few weeks in the south of France, he set out for Paris, in company with Buffon, to whom he communicated much valuable information which that celebrated naturalist has acknowledged in his advertisement to the third volume of the History of Birds. His health being still unconfirmed, he left the French capital in July, and made a second tour into Italy where he resided till the spring of 1774, when he again returned to France, and thence proceeded to England, which he reached in June following, after an absence of twelve years. Previously to leaving Scotland, he had contracted an engagement with a lady, whom, during his travels, he never forgot; and he was so incensed, on his arrival at Rome, on hearing that she had married an Italian marquess, that he insisted on fighting with her husband, who, however, declined the challenge. After remaining some months in London, he returned to his mansion at Kinnaird, to regulate his private affairs, which he found greatly disordered in consequence of his relations having supposed him dead, and taken possession of great part of his effects; to prevent a recurrence of which, he married the daughter of Thomas Dundas, Esq., of Fingask, who, after bearing him three children, died in the spring of 1785.