Five Weeks in a Ballon Jules Verne

It was then about one hundred miles from Kazeh, an important establishment in the interior of Africa, where, thanks to a south-southeasterly current, the travellers might hope to arrive on that same day. They were moving at the rate of fourteen miles per hour, and the guidance of the balloon was becoming difficult, as they dared not rise very high without extreme dilation of the gas, the country itself being at an average height of three thousand feet. Hence, the doctor preferred not to force the dilation, and so adroitly followed the sinuosities of a pretty sharply-inclined plane, and swept very close to the villages of Thembo and Tura-Wels. The latter forms part of the Unyamwezy, a magnificent country, where the trees attain enormous dimensions; among them the cactus, which grows to gigantic size.