'There are most essential secrets connected with the structure and working of this remarkable "chariot of the skies" which no one but my master understands, and he takes good care to keep them to himself,' he declared. 'When you reach Mars, for instance, you will see there numerous airships and flying-machines of many kinds. It has, indeed, been much easier for the Martians to learn to build such contrivances than for the dwellers upon the Earth, because, as I have before mentioned, the air upon Mars is so much denser. But though you will see many such things flying about, you will not see one that can compare with this; not one that can venture out into space, or, indeed, very far above the surface of the planet.'

Often Mr Armeath accompanied the young people, and listened with interest to the engineer's explanations; for, scientist though he was, he found he had almost as much to learn in their new surroundings as they had.

Truly, the great airship was a wonder from every point of view. It may assist readers to understand the stupendous scale upon which she had been designed if it is explained that she was more than twice the size of Britain's great warship the Dreadnought. But nothing less in bulk would have been of any use if we consider the tremendous strength required, and the accommodation necessary for the number of people she carried—of whom there were between two and three thousand. In addition, room had to be provided for enormous quantities of stores and other equipment.

Another feature which illustrates the gigantic scale upon which everything was carried out was to be found in the fact that a large space was given up to ornamental gardens and conservatories. In these were graceful, waving, palm-like trees, wondrous flowers and shrubs, and trees growing delicious fruits, interspersed amongst fountains and pleasant walks, with what appeared to be a sunny sky overhead. There was even a sort of 'Zoo' or menagerie on board, in which were many very curious animals which the new passengers had never seen or heard of before. To these had now been added quite a collection of more familiar creatures which King Ivanta had acquired during his stay upon Earth, and was taking back for the edification of his subjects at home.

The chums were fond of wandering about in this miniature zoological garden, looking at those creatures which were new to them, and studying their ways and habits. Some were natives of Mars; these were mostly small, for—as they soon learned from Monck—just as Mars was a smaller globe than the Earth, so the animals generally were smaller in proportion. But in this Zoo were specimens brought, as it appeared, from the great planet Saturn, some of which were large and terrible creatures.

It was with one of these that Gerald met with an unpleasant adventure one day when they had been but a short time 'out.' He had strolled in alone, in the early morning, as was now his almost constant habit, and went towards the cage of a creature called by the Martians an amalpi. Gerald was especially interested in it on account of its resemblance to an immense unicorn. It was, indeed, something between that fabled creature and a rhinoceros. It had a very long, straight, sharp horn upon the frontal bone, and a body very much like a heavily-built cart-horse, covered with skin almost as thick as that of an elephant. It was a most savage, dangerous creature, and all attempts to tame it, even in the smallest degree, had failed.

When Gerald walked up to its cage on this particular occasion he met with a surprise, for the cage was empty and the barred gate was standing ajar. Ere he had time to consider what this might mean he received a second surprise. There was a loud, bellowing roar, and the next he knew was that the creature itself was charging down upon him with lowered head like a bull, the terrible, long, sharp horn pointed straight at him.

For an instant the young fellow stood as if spell-bound; then, by a happy flash of thought, he dashed into the empty cage and pulled the gate to after him. It fastened, as he knew, automatically, with a huge spring-catch. A moment later there was a frightful crash as the ferocious animal ran full tilt at the bars, its long horn pushing between them, and just failing to reach Gerald by some few inches.

For some time he had the novel experience of being a prisoner in the great cage, while his enemy, furious with disappointment, charged again and again at the bars. Such was the strength and determination of its rushes that it seemed almost as if the bars must give way.

At last the noise of its bellowing brought some of the keepers upon the scene. Then Gerald had an opportunity of learning more of the weapons the Martians were armed with, and how they used them. Each keeper carried in his hand one of the large wands or staves, with triple points at the top, similar to those the soldiers had carried who had marched Gerald as a prisoner before the 'Ogre' and his chief. Gerald had seen similar wands many times since, but had never seen how they were used. Nor was he, indeed, much the wiser now. All he saw was a slight flash of very brilliant light which seemed to leap from the tridents towards the great roaring animal, as it stood for a moment tossing its head and stamping its feet ere charging down upon the rescue-party. But it never started upon its rush, for, lo! it suddenly sank upon its knees and rolled helplessly over upon the ground, where it lay quiet and still—a big, inert mass.