From:  http://www.1911encyclopedia.org/Joseph_Thomson

JOSEPH THOMSON (1858-1895), Scottish explorer in Africa, was born on the 14th of February 1858 at Penpont, Dumfriesshire, being the fifth son of William Thomson, originally a working stonemason, who had attained the position of a master builder. In 1868 his father removed to Gatelawbridge, where he rented a farm and a quarry.

Joseph Thomson was soon attracted by the geological formation and historical associations of Nithsdale. For a short time he worked in his father's quarry. In 1875 he went to Edinburgh University, where he paid particular attention to geology and botany, and after completing his course in 1878 he was appointed geologist and naturalist to the Royal Geographical Society's expedition to East Central Africa under Keith Johnston. The latter died at Behobeho, between the coast and the north end of Lake Nyasa, on the 28th of June 187 9, and Thomson then took command.

Though only twenty one his coolness and tact were remarkable, and he successfully conducted the expedition across the desolate region of Uhehe and Ubenato the north end of Lake Nyasa, and then by a hitherto unexplored trackto Lake Tanganyika, where he investigated the moot question of the Lukuga outlet. From Tanganyika he started to reach the Congo, but troubles with his carriers, who dreaded the warlike Warua, obliged him to retrace his steps. Going round the south end of Tanganyika he discovered Lake Rukwa, whence he marched via Tabora to the coast at Bagamoyo, reaching London in August 1880. In the following year he published an account of his travels under the title To the Central African Lakes and Back. About this time the sultan of Zanzibar, being anxious to develop certain supposed coal beds on the river Rovuma, was advised to obtain independent expert opinion as to their value. Application was made to Thomson, who undertook to survey them, and started from Mikindani, on the 17th ofJuly 1881. The coal, however, turned out to be merely bituminous shale, and Thomson, on his return to Zanzibar, had to endure much delay and vexation through the sultan's chagrin.

For a considerable time theexplorer had directed his attention to Masailand, a region of EastAfrica occupied by a powerful tribe of warriors who had a reputation for savagery and intractability somewhat greater than their actions warranted. Through their territory ran the shortest route from the seato the headwaters of the Nile.

 

In 1882 the Royal Geographical Society took up the question, and requested Thomson to report on the practicability of taking a caravan through the Masai country, which no European had yet been able to penetrate beyond Mt Kilimanjaro. By undaunted courage and great resourcefulness he succeeded in crossing the Njiri desert and exploring the eastern rift-valley. Thence he went with a picked company through Laikipia to Mt Kenya and Lake Baringo, afterwards traversing the unknown region lying between Baringo and Victoria Nyanza, reached on the 10th of December 1883. On his way back he visited Mt Elgon and discovered there a series of wonderful caves. The account of this adventurous journey appeared in 1884, under the title of Through Masailand, and it is a classic in modern travel.

The hardships and anxieties attendant on such a career began to tell upon Thomson's exceptionally hardy constitution, but in 1885 he undertook an expedition to Sokoto for the National African (afterwards the Royal Niger) Company, and succeeded in obtaining the signatures of the sultans of Sokoto and Gando to treaties with which he had been entrusted by the company, treaties which did much to secure British interests in Nigeria. In 1888, by way of recreation, he travelled through southern Morocco and explored a portion of the Atlas range, and published the results in the following year, under the title Travels in the Atlas and Southern Morocco. In 1890 he entered the service of the British South Africa Company and in that and the following year, starting from Quilimane he traversed the region between lakes Nyasa and Bangweulu and the Zambezi.

 

It was a period of great tension between the Portuguese and the British, and Thomson's party on leaving the Portuguese frontier was fired on by the Portuguese who, too late, realized that they had allowed a treaty-making envoy to pass through their territory in the guise of a peaceful trader. Thomson concluded treaties with native potentates which gave to the Chartered Company political, trading and mining rights over a large part of the district since known as North-East Rhodesia. This journey, in which he covered nearly a thousand miles of hitherto unexplored country, proved disastrous to a constitution already undermined.

In 1893 he visited South Africa in search of health, but unavailingly. He died in London on the 2nd of August 1895. The accounts of his travels not recorded in the books mentioned were published in magazines or in the Proceedings of the Royal Geographical Society. Thomson was the last, as he was one of the most successful, of the great geographical pioneers in Africa. He had an extraordinarily keen topographical instinct which enabled him to comprehend at a glance the natural features of the countries he traversed. To undaunted courage and promptness of decision he added a forbearing and patient disposition. "Joseph Thomson," wrote Sir Clements Markham, "had the high and glorious distinction of never having caused the death of a native. This is a proof of very rare qualities in the leader of an expedition, and places him in the very first rank of explorers. "Besides the accounts of his own travels Thomson wrote, in collaboration with Miss E. Harris Smith, Ulu (London, 1888), a novel based on his insight into the working of the African mind, Mungo Park and the Niger (London, 1890), a sound critical biography and many magazine articles on African politics.

See Joseph Thomson, African Explorer (London, 1896), abiography by his brother, the Rev. J. B. Thomson, which contains a list of the published writings of the explorer.