The work to be done in all cases was threefold. First, in the places where there was a deficiency of water--of which places there were several in the lower sections, particularly in the deserts of Duruma, Teita, and Ngiri--wells had to be dug and, where there was no spring-water, cisterns made capacious enough to supply water sufficient not merely for the workmen during the construction of the road, but afterwards for the men and cattle of the caravans that passed that way. As there occur in Equatorial Africa at all seasons of the year heavy storms of rain, which in the so-called hot season are only much less frequent than in the so-called rainy season, there was no danger that large cisterns draining the rain-water from a sufficiently wide area would be exhausted even in the hot months; but the cisterns had to be protected from the direct rays of the sun as well as from impurities. The former was effected by providing the cisterns with covering and shelter; the second by making the rain-water filter through layers, several yards thick, of sand and gravel. The natural water-holes, which are found in all deserts, but which dry up in times of protracted drought, indicated the spots where it would be most practicable to construct cisterns, for such spots were naturally the lowest points. The larger of these water-holes needed only to be deepened, the evaporation of the water guarded against, and the cisterns surrounded by the above-mentioned natural filter, and the work was then finished. Of these in the different sections twenty five were dug, with a depth of from nine to sixteen yards and a diameter of from two to nine yards. Of ordinary wells with spring-water thirty-nine were made. Each of these artificial supplies of water was placed under the protection of a watchman. In the second place, there was the road-making itself. In general, the route which the expedition had taken from Mombasa to the Kenia was chosen, and merely freed from obstacles and widened to twice its original width where it led through bush. But at certain places, particularly where steep heights had to be traversed, it was necessary to look for a fresh and less hilly track. That several bridges had to be built scarcely need be mentioned. The third part of the work consisted in the erection of primitive houses of shelter, at suitable places, for both men and cattle. Accommodation for several hundred men, pens for cattle, and storehouses for provisions, were constructed at sixty-five stations, at distances varying from seven to twelve miles.