“We are now in the region of the usurper’s strongest support,” he told them. “It was the hotbed of traitors before he stole the throne, executing many of my loyal leaders. These people have, no doubt, been notified to be on the lookout for us and will try to destroy us with their _hilwai_ if we approach within range.” Hakon explained further that _hilwai_ were a kind of large gun, electrically operated, in lieu of the obsolete kind in which explosives had been used in previous centuries, before the planet’s mineral supply had been virtually exhausted. These guns had a range of about twenty miles horizontally. Though this was not a very great distance, considering the weak gravity on Mars, it was sufficient to make it uncomfortably dangerous for them if they undertook to view the “caret” at close range. Hakon was surprized to learn of their curiosity regarding the dark blotches and their caret-shaped junctures wherever they were joined to a canal, and readily explained this phenomenon. “The dark regions are vast, low sections which were covered by seas ages ago,” he informed them. “The carets are formed by two branches from the main canal where it enters the low region. From these fanlike branches, and the main canal which crosses the bottom, the low country extending beyond is fed. Thus the lowlands, which formerly formed the sea bottom, are cultivated, resulting in the largest, richest and most productive regions on the planet. Even small, precious lakes are formed in the lowest spots, and occasionally there are light falls of rain, which are unknown in any other parts of the planet.” Circling this region at a comfortable height, the adventurers examined it in turn through a telescope. What they saw tallied with Hakon’s explanation. The denser vegetation, fed directly from the main canal running across the bottom, appeared as a slightly darker strip. Two small lakes were visible. Both of these appeared to be only a mile or two in circumference. The western edge of the low region was hidden in a light cloud bank. Leaving this region behind, Robert pushed on toward the polar region ahead at full speed. After an hour had passed thus, Hakon suggested descending closer to the surface, that he might watch for landmarks to direct them to their objective. Though the country here looked much like that near the equator, there seemed to be fewer canals; at any rate, there were fewer latitudinal canals, for they had crossed very few during the last half hour. However, they had the opportunity of observing one of the “double” canals, which was really two canals running parallel, some seventy-five miles apart. Hakon explained that this was in order to take advantage of exceptionally productive districts which justified this deviation from the regular scheme. 16