Lennard's first feelings after the receipt of Mr Parmenter's cablegram, and the casting of the vast mass of metal which was to form the body of the great cannon, were those of doubt and hesitation, mingled, possibly, with that sense of semi-irresponsibility which will for a time overcome the most highly-disciplined mind when some great task has been completed for the time being.

For a full month nothing could be done to the cannon, since it would take quite that time for the metal to cool. Everything else had been done or made ready. The huge projectile which was to wing its way into Space to do battle for the life of humanity was completed. The boring and rifling tools were finished, and all the materials for the driving and the bursting charges were ready at hand for putting into their final form when the work of loading up began. There was literally nothing more to be done. All that human labour, skill and foresight could achieve for the present had been accomplished.

Dearly would he have loved to go south and join the ranks of the fighters; but a higher sense of duty than personal courage forbade that. He was the only man who could perform the task he had undertaken, and a chance bullet fragment of a shell to say nothing of the hundred minor chances of the battlefield, might make the doing of that work impossible.

No, his time would come in the awful moment when the fate of humanity would hang in the balance, and his place alike of honour and of duty was now in the equatorial room of the observatory at Whernside, watching through every waking hour of his life the movements of the Invader, that he might note the slightest deviation from its course, or the most trifling change in its velocity. For on such seemingly small matters as these depended, not only the fate of the world, but of the only woman who could make the world at least worth living in for him—and so he went to Whernside by the morning train after a long day's talk with Tom Bowcock over things in general.

"Yo' may be sure that everything will be all right, Mr Lennard," said Tom, as they shook hands on the platform. "I'll take t' temperatures, top, bottom and middle, every night and morning and post them to yo', and if there's any change that we don't expect, I'll wire yo' at once; and now I've a great favour to ask you, Mr Lennard. I haven't asked it before because there's been too much work to do—"

"You needn't ask it, Tom," laughed Lennard, as he returned his grip, "but I'm not going to invite you to Whernside just yet, for two reasons. In the first place, I can't trust that metal to anyone else but you for at least a week; and in the second place, when I do send you an invitation from Mr Parmenter I shall not only be able to show you the comet a bit brighter than it is just now, but something else that you may have thought about or read about but never seen yet, and I am going to give you an experience that no man born in England has ever had—but I'm not going to spoil sport by telling you now."

"Yo've thought it all out afore me, Mr Lennard, as yo' always do everything," replied Tom. "I'm not much given to compliments, as yo' know, but yo're a wonderful man, and if yo've got something to show me, it's bound to be wonderful too, and if it's anything as wonderful as t' lies I've b'n telling those newspaper chaps about t' cannon, I reckon it'll make me open my eyes as wide as they've ever been, for sure. Good-bye."

During the journey to Settle, Lennard began to debate once more with himself a question which had troubled him considerably since he had received Mr Parmenter's cablegram. Should he publish his calculations to the world at once, give the exact position of the Invader at a given moment in a given part of the sky, and so turn every telescope in the civilised world upon it—or should he wait until some astronomer made the independent discovery which must come within a short time now?

There were reasons both for and against. To do so might perhaps stop the war, and that would, at first sight, be conferring a great blessing upon humanity; but, on the other hand, it might have the very reverse effect upon the millions of men whose blood was now inflamed with the lust of battle. Again it was one thing to convince the rulers of the nations and the scientists of the world that the coming catastrophe was inevitable; but to convince the people who made up those nations would be a very different matter.

The end of the world had been predicted hundreds of times already, mostly by charlatans, who made a good living out of it, but sometimes by the most august authorities. He had read his history, and he had not forgotten the awful conditions in which the people of Europe fell during the last months of the year 1000, when the Infallible Church had solemnly proclaimed that at twelve o'clock on the night of the 31st of December Satan, chained for a thousand years, would be let loose; that on the morning of the 1st of January 1001 the order of Nature would be reversed, the sun would rise in the west and the reign of Anti-Christ begin. Then the remnants of the European nations had gradually awakened to the fact that Holy Church was wrong, since nothing happened save the results of the madness which her prophesies had produced.

But the catastrophe of which he would have to be the prophet would be worse even than this, and, moreover, as far as human science could tell, it was a mathematical certainty. There would be no miracle, nothing of the supernatural about it—it would happen just as certainly as the earth would revolve on its axis; and yet how many millions of the earth's inhabitants would believe it until with their own eyes they saw the approaching Fate?

In time of peace perhaps he might have obtained a hearing, but who would pause amidst the rush of the armed battalions to listen to him? How could the calm voice of Science make itself heard among the clash and clangour of war? The German Emperor had already laughed in his face, and accepted his challenge with contemptuous incredulity. No doubt his staff and all his officers would do the same. What possibility then would there be to convince the millions who were fighting blindly under their orders? No; it was hopeless. The war must go on. He could only hope that the AËrial Fleet which Mr Parmenter was bringing across the Atlantic would turn the tide of battle in favour of the defenders of Britain.

But there was another matter to be considered. Thanks to the control possessed by the Parmenter Syndicate over the Atlantic cables and the aerograph system of the world, he was kept daily, sometimes hourly, acquainted with everything that was happening. He knew that the Eastern forces of Russia were concentrating upon India in the hope that the disasters in England and the destruction of the Fleet would realise the old Muscovite dream of detaching the natives from their loyalty to the British Crown and so making the work of conquest easy. In the Far East, Japan was recovering from the exhaustion consequent upon her costly victories over Russia, and had formed an ominous alliance with China.

On the other hand Italy, England's sole remaining ally in Europe, had blockaded the French Mediterranean ports, and while the French legions were being drawn northward to the conquest of Britain, the Italian armies had seized the Alpine passes and were preparing an invasion which should avenge the humiliations which Italy had suffered under the first Napoleon.

In a word, everything pointed to universal war. Only the United States preserved an inscrutable silence, which had been broken only by four words: "Hands off our commerce." And to these the Leagued Nations had listened, if rather by compulsion than respect.

Who was he, then, that he should, as it were, sound the trump of approaching doom in the ears of a world round which from east to west and from west again to east the battledrums might any day be sounding and the roar of artillery thundering its answering echo.

But a somewhat different aspect was given to these reflections by a letter which he found waiting for him in the library at Whernside House. It ran thus:

"Sir,—You will not, I suppose, have forgotten a certain incident which happened towards the end of June 1907 in the Bay of Clifden, Connemara. You won that little swimming race by a yard or so, and since then it appears to me that, although you may not be aware of it, you and I have been running a race of a very different sort, although possibly for the same prize.

"You will understand what prize I mean, and by this time you ought to know that I have the power of taking it by force, if I cannot win it in the ordinary way of sport or battle. I am in command of the only really irresistible force in the world. I created that force, and, by doing so, made the invasion of England and the present war possible. I have done so because I hate England, and desire to release my own country from her tyranny and oppression; but I can love as well as I can hate, and whether you understood it or not, I, who had never loved a woman before, loved Auriole Parmenter from the moment that you and I lifted her out of the water, and she smiled on us, and thanked us for saving her life.

"Before we parted that day I could see love in your eyes when you looked at her, if you could not see it in mine. You are her father's private astronomer, and until lately you have lived in almost daily intercourse with her, in which, of course, you have had a great advantage over myself, who have not from that time till now been blessed by even the sight of her.

"But during that time it seems that you have discovered a comet, which is to run into the earth and destroy all human life, unless you prevent it. I know this because I know of the challenge you gave to the German Emperor in Canterbury. I know also of what you have been doing in Bolton. You are turning a coal pit into a cannon, with which you believe that you can blow this comet into thin air or gas before it meets the earth, and you threatened His Majesty that if the war was not stopped the human race should be destroyed.

"That, if you will pardon the expression, was a piece of bluff. You love Miss Parmenter perhaps as much as, though not possibly more than, I do, and therefore you would certainly not destroy the world as long as she was alive in it. You would be more or less than man if you did, and I don't believe you are either, and therefore I think you will understand the proposition I am going to make to you.

"Granted hypothesis that the world will come to an end by means of this comet on a certain day, and granted also that you are able to save it with this cannon of yours, I write now to tell you that, whether the war stops or not in obedience to your threat, I will not allow you to save the world unless Miss Parmenter consents to marry me within two months from now. If she does, the war shall stop, or at anyrate I will allow the British forces to conquer the whole of Europe on the sole condition of giving independence to Ireland. They cannot win without my fleet of Flying Fishes, and if I turn that fleet against them they will not only be defeated but annihilated. In other words, with the sole exception of my own country, I offer England the conquest of Europe in exchange for the hand of one woman.

"In the other alternative, that is to say, if Miss Parmenter, her father and yourself do not consent to this proposal, I will not allow you to save the world. I can destroy your cannon works at Bolton as easily as I destroyed the forts at Portsmouth and Dover, and as easily as I can and will kill you, and wreck your observatory. When I have done this I will take possession of Miss Parmenter by force, and then your comet can come along and destroy the world as soon as it likes.

"I shall expect a definite answer to this letter, signed by Mr Parmenter and yourself, within seven days. If you address your letter to Mr James Summers, 28a Carlos Street, Sheerness, it will reach me; but I must warn you that any attempt to discover why it will reach me from that address will be punished by the bombardment and destruction of the town.

"I hope you will see the reasonableness and moderation of my conditions, and remain, yours faithfully,

"John Castellan."