were more certain harbingers of inevitable doom than were those which bore this dreaded name. Whether he were high or low, the man who received one of them made ready for his end. He knew not where or when the fatal blow would be struck. He only knew that the invisible hand of the Terror would strike him as surely in the uttermost ends of the earth as it would in the palace or the fortress. Never once had it missed its aim, and never once had the slightest clue been obtained to the identity of the hand that held the knife or pistol.
Some such thoughts as these flashed one after another through Arnold’s brain as he stood talking with Natasha. He saw at once why she had only that one name. It was enough, and it was not long before he learnt that it was the symbol of an authority in the Circle that admitted of no question.
She was the envoy of him whose word was law, absolute and irrevocable, to every member of the Brotherhood; to disobey whom was death; and to obey whom had, so far at least, meant swift and invariable success, even where it seemed least to be hoped for.
Of course, Natasha’s almost girlish question about the air-ship was really a command, which would have been none the less binding had she only had her own beauty to enforce it. As she spoke the President and Colston — who had only lost himself for the time behind a mask and cloak — came up to Arnold and asked him if he was prepared to give an exhibition of the powers of his model, and to explain its working and construction to the Circle at once.
He replied that everything was perfectly ready for the trial, and that he would set the model working for them in a few minutes. The President then told him that the exhibition should take place in another room, where there would be much more space than where they were, and bade him bring the box and follow him.
A door was now opened in the wall of the room remote from that by which he and Colston had entered, and through this the whole party went down a short passage, and through another door at the end which opened into a very large apartment, which, from the fact of its being windowless, Arnold rightly judged to be underground, like the Council-chamber that they had just left.
A single glance was enough to show him the chief purpose to which the chamber was devoted. The wall at one end was covered with arm-racks containing all the newest and most perfect makes of rifles and pistols; while at the other end, about twenty paces distant, were three electric signalling targets, graded, as was afterwards explained to him, to one, three, and five hundred yards range.
In a word, the chamber was an underground range for rifle and pistol practice, in which a volley could have been fired without a sound being heard ten yards away. It was here that the accuracy of the various weapons invented from time to time was tested; and here, too, every member of the Circle, man and woman, practised with rifle and pistol until an infallible aim was acquired. A register of scores was kept, and at the head of it stood the name of Radna Michaelis.
A long table ran across the end at which the arm-racks were, and on this Arnold laid the case containing the model, he standing on one side of the table, and the members of the Circle on the other, watching his movements with a curiosity that they took no trouble to disguise.
He opened the case, feeling something like a scientific demonstrator, with an advanced and critical class before him. In a moment the man disappeared, and the mechanician and the enthusiast took his place. As each part was taken out and laid upon the table, he briefly explained its use; and then, last of all, came the hull of the air-ship.
This was three feet long and six inches broad in its midships diameter. It was made in two longitudinal sections of polished aluminium, which shone like burnished silver. It would have been cigar-shaped but for the fact that the forward end was drawn out into a long sharp ram, the point of which was on a level with the floor of the hull amidships as it lay upon the table. Two deep bilge-plates, running nearly the whole length of the hull, kept it in an upright position and prevented the blades of the propellers from touching the table. For about half its whole length the upper part of the hull was flattened and formed a deck from which rose three short strong masts, each of which carried a wheel of thin metal whose spokes were six inclined fans something like the blades of a screw.
A little lower than this deck there projected on each side a broad, oblong, slightly curved sheet of metal, very thin, but strengthened by means of wire braces, till it was as rigid as a plate of solid steel, although it only weighed a few ounces. These air-planes worked on an axis amidships, and could be inclined either way through an angle of thirty degrees. At the pointed stern there revolved a powerful four-bladed propeller, and from each quarter, inclined slightly outwards from the middle line of the vessel, projected a somewhat smaller screw working underneath the after end of the air-planes.
The hull contained four small double-cylinder engines, one of which actuated the stern-propeller, and the other three the fan-wheels and side-propellers. There were, of course, no furnaces, boilers, or condensers. Two slender pipes ran into each cylinder from suitably placed gas reservoirs, or power-cylinders, as the engineer called them, and that was all.
Arnold deftly and rapidly put the parts together, continuing his running description as he did so, and in a few minutes the beautiful miracle of ingenuity stood complete before the wondering eyes of the Circle, and a murmur of admiration ran from lip to lip, bringing a flush of pleasure to the cheek of its creator.
“There,” said he, as he put the finishing touches to the apparatus, “you see that she is a combination of two principles — those of the Aëronef and the Aëroplane. The first reached its highest development in Jules Verne’s imaginary “Clipper of the Clouds,” and the second in Hiram Maxim’s Aëroplane. Of course, Jules Verne’s Aëronef was merely an idea, and one that could never be realised while Robur’s mysterious source of electrical energy remained unknown — as it still does.
“Maxim’s Aëroplane is, as you all know, also an unrealised ideal so far as any practical use is concerned. He has succeeded in making it fly, but only under the most favourable conditions, and practically without cargo. Its two fatal defects have been shown by experience to be the comparatively overwhelming weight of the engine and the fuel that he has to carry to develop sufficient power to rise from the ground and progress against the wind, and the inability of the machine to ascend perpendicularly to any required height.
“Without the power to do this no air-ship can be of any use save under very limited conditions. You cannot carry a railway about with you, or a station to get a start from every time you want to rise, and you cannot always choose a nice level plain in which to come down. Even if you could the Aëroplane would not rise again without its rails and carriage. For purposes of warfare, then, it may be dismissed as totally useless.
“In this machine, as you see, I have combined the two principles. These helices on the masts will lift the dead weight of the ship perpendicularly without the slightest help from the side-planes, which are used to regulate the vessel’s flight when afloat. I will set the engines that work them in motion independently of the others which move the propellers, and then you will see what I mean.”
As he spoke, he set one part of the mechanism working. Those watching saw the three helices begin to spin round, the centre one revolving in an opposite direction to the other two, with a soft whirring sound that gradually rose to a high-pitched note.
When they attained their full speed they looked like solid wheels, and then the air-ship rose, at first slowly, and then more and more swiftly, straight up from the table, until it strained hard at the piece of cord which prevented it from reaching the roof.
A universal chorus of “bravas” greeted it as it rose, and every eye became fixed on it as it hung motionless in the air, sustained by its whirling helices. After letting it remain aloft for a few minutes Arnold pulled it down again, saying as he did so —
“That, I think, proves that the machine can rise from any position where the upward road is open, and without the slightest assistance of any apparatus. Now it shall take a voyage round the room.
“You see it is steered by this rudder-fan under the stern propeller. In the real ship it will be worked by a wheel, like the rudder of a sea-going vessel; but in the model it is done by this lever, so that I can control it by a couple of strings from the ground.”