In 1898 Dubois conceived the idea of launching the first general freight company to use trucks, avoiding the need for porters in the French Sudan and also turning a profit.

Dubois spent several years in Paris before embarking on another expedition in 1907, this time crossing the Sahara from north to south.

He found relics of ancient civilizations in the Hoggar Mountains of southern French Algeria, but was unable to take the time to explore them properly.

In 1890 L'Illustration asked him to accompany and report on the expedition led by Henri Brosselard-Faidherbe to explore Guinea and the sources of the Niger River.

[8] On the other hand, he wrote of these people: A wonderful impulse was imparted to this country in the sixteenth century, and a marvellous civilisation appeared in the very heart of the black continent.

This civilisation was not imposed by circumstances and force, as is so often the case, even in our own countries, but was spontaneously desired, evoked, and propagated by a man of the negro races.

Unfortunately, its fairest promises were never fulfilled, owing, not so much to the native successors, as to the civilised (some say white) peoples who ruthlessly destroyed all this good seed, and caused the tares of barbarism to sprout anew.

[13] In 1897 Dubois was recruited by the French colonial authorities to accompany a military expedition under Captain Marius Gabriel Cazemajou to reach Chad before the British.

[3] In the fall of 1898 Dubois attended an exhibition of cars and bicycles which gave him the idea of introducing motorized wagons into the French Sudan in place of porters.

Trentinian had been removed from office, the local authorities were hostile to the enterprise, the European staff and Chinese drivers were incompetent and became ill, the roads had deteriorated from overuse and poor maintenance, and there was an epidemic of yellow fever.

[14] Despite all this, Dubois managed to deploy 55 vehicles with fuel drums, and made a symbolic journey from Kati to Bamako on 1 January 1900 that was widely reported in the international press.

[17] Dubois lost all his money but retained his reputation, and in 1900 was special commissioner for the French Sudan at the Exposition Universelle.

Dubois inherited some of the royalty rights to his father's books, and made fairly profitable investments with the capital.

[17] In 1907, at the age of 45, Dubois was assigned another official mission in Africa, to cross the Sahara without escort from Algeria to the Sudan.

Dubois was to study the people of the Sahara, the conditions of the region and the possibility of establishing regular commercial contacts between Algeria and Sudan.

[18] He was fascinated by his findings of traces of ancient civilization, and dreamed of returning with a better equipped expedition to undertake a more careful and focused study of the topography, archaeology and ethnography of the region.

[19] From the Hoggar Mountains Dubois's route took him south to Gao, then west to Timbuktu, which was now a quiet colonial town, and from there up the Niger to Koulikoro and then by train to Kayes.

His last book Notre beau Niger (1911) celebrated the social and economic benefits that the French colonial rule had brought to West Africa.

His account of his travel in the desert, L'enigme du Sahara, was advertised as due to appear after Notre Beau Niger.

[23] In January 1913 he launched a company with a capital of 6 million gold roubles to exploit the resources of the Kuznetsk Basin in Siberia.

During World War I he traveled to Canada, where he became interested in the Alberta oilfields, and continued to invest in this area until at least 1925, again losing his money.