"Well," remarked John, "some of our millionaires would give half their fortunes to have such lovely bridges as these in their private parks!" "Heh, mon!" replied M'Allister, "it's very clear the Martians could teach our engineers something about bridge-building, if nothing else!" "Wait and see our water-lifting and water-propelling machinery," said Merna; "I think that will be something which will suit you as an engineer!" I noticed that many of the lines were apparently groves of trees, and asked Merna whether they were canals or not. "Yes," he replied, "they are canals. You will understand that in the hotter parts of our world it is necessary to protect the water from too rapid evaporation, or else the canals would be almost run dry long before the need for their use ceased at the end of the season. Some are arched over entirely, but in most cases it is sufficient to plant trees along each side. Would you like to examine one?" he asked; "we can do so very soon, if you wish?" I said I should be glad to do so, and our course was accordingly directed to one of the groves, which appeared to be about two miles distant. It, however, proved to be more than six miles away, for we had not yet become accustomed to the effect of the clear Martian air in making distant objects appear much closer than they really were. However, it did not take long for our air-ship to reach it; and we descended in the space between the canals and then walked over into the grove. When we turned into it, we were greatly surprised at the charming effect of the trees over the canal. The trees were something like our willows, but taller than elms, and had a multitude of very long, thin, and supple branches, with very little bare trunk. They were planted rather close together, all along each side of the canal, with their trunks sloping slightly towards the water. The long branches thus met at the sides and high overhead, intertwining together, and forming a high leafy archway extending all along the canal in both directions as far as the eye could see. The thick, soft Martian grass along each side of the canal was like a velvet-pile carpet to walk upon; the sunlight filtering between the green leaves of the trees cast bright flecks of light on the clear shimmering water which ran beneath them; whilst water-fowl swimming here and there gave a bright touch of colour and the animation of life which so adds to the general charm of such scenery. Some of the water-fowl were very large birds, with brilliant coloured plumage. "What a delightful place for a quiet walk on a hot day like this," I exclaimed; "plenty of air and no excess of heat!"