He accordingly directed his course towards the chosen spot; but we had not proceeded very far before everything below us suddenly disappeared, being quite blotted out by something of an ochre tint, which entirely obscured our view of the country.
"Professor," exclaimed M'Allister, "what is the matter? I cannot see where we are going!"
"I can guess what it is," I replied; "we have run into one of those sand-clouds I told you of the other evening, and until we get through, or it passes away, we shall see nothing else. Perhaps we had better go on very slowly."
We went on accordingly, but instead of our getting through it, the cloud seemed to become denser and denser. However, we still pressed on, and, after what seemed quite a long time, we emerged into somewhat clearer air, although there was still a thin yellow cloud below us. Our course had been well maintained, for we seemed to be within ten miles of our destination, which we could just make out through the thin dust-cloud.
Presently M'Allister called out to me, "Professor, I don't know what is wrong, but the machinery is slowing down so much that I am afraid we shall soon come to a dead stop! I have switched on more power, but it does not seem to make any difference!"
"Well, try a little stronger current," I suggested; "but be careful not to overdo it, or we may land upon Mars more suddenly than we shall like."
He tried this, but we had not moved more than a hundred yards when he found that farther progress was impossible. So here we were, only a few miles from our destination, yet prevented by an impalpable and unknown obstacle from reaching it!
We consulted together, but could find no solution of the mystery of this invisible barrier to our progress. Then John suggested that, as we could not go straight on, we should try a different course. So M'Allister altered our course a few points, and once more put on the speed power, only to be brought to a standstill again after a very short spurt.
"My word!" he exclaimed, "I'll not be beaten like this. I've driven an old iron tramp-steamer through scores of miles of thick seaweed out in the tropics, although the machinery was almost worn out and the engines leaking at every joint. Here goes for full speed ahead!" he cried; and, so saying, he switched on full power, quite heedless of my shout of "Do be careful, M'Allister, or we shall all be smashed to pieces!"