It is true that Idris gave her the easiest carrying camel and had made an excellent saddle so that she could sleep in it lying down; nevertheless the desert air, which she breathed day and night, mainly gave her strength to endure the hardships and irregular hours.
"In Desert and Wilderness"
Henryk Sienkiewicz
The surface of Mercury is probably rough and irregular and much like the moon.
"Lectures in Navigation"
Ernest Gallaudet Draper
Progress, however, was quite as difficult as over the irregular pack.
"My Attainment of the Pole"
Frederick A. Cook