"That is the only explanation, Mr. Devoran. It is five hours since the apparatus, sensitive enough in all purpose, has recorded any movement. Well, Carnon?" "’Persia’ in sight, sir," replied the quartermaster, who had taken up his position, telescope in hand, on top of the fore conning-tower. "Capital!" exclaimed Captain Restronguet. "She’ll be close alongside within half an hour. Pass the word to the leading boat, Mr. Devoran, and tell them to stand by ready to cast off." Rapidly the "Persia" approached, then, laying-to to windward of the string of boats, waited for them to be towed under her lee. Boat after boat discharged its band of passengers, the empty craft being turned adrift, and within half an hour of the liner’s arrival five hundred Dutchmen had found shelter under the Blue Ensign. Great though the attention was towards the rescued men the chief object of interest to the British passengers and crew of the "Persia" was the strangely unfamiliar outline of the "Aphrodite." Much had been heard of the mysterious submarine, the avowed rival of the piratical "Vorwartz," and now the liner’s people had a unique opportunity of viewing her at close quarters. When the work of transferring the rescued Dutchmen was completed Captain Restronguet took off his cap and saluted the captain of the huge liner. Simultaneously a tremendous burst of cheering came from throats of hundreds; and with the echoes of the prolonged chorus of welcome and approbation ringing in their ears, the crew of the "Aphrodite" quietly yet majestically disappeared beneath the waves. CHAPTER XIX. STRUCK BY LIGHTNING. "It’s a jolly fortunate thing that we fell in with the ’Persia,’" remarked Kenwyn, within two hours of parting company with the liner. "Otherwise it would have been a serious matter with those Dutchmen in the boats." "You are right," assented Devoran. "It is going to be dirty weather. The glass is falling rapidly." "It will soon be over," observed Hythe. "’Long foretold, long last; short notice, soon past.’ That’s how the rhyme goes, doesn’t it?" "And a brute of a business while it lasts," added the second officer. The three officers were standing on the after deck of the "Aphrodite." The submarine had again risen to the surface and was plugging away in a southerly direction on her vague quest for the unbeatable "Vorwartz." Captain Restronguet remained below, absorbed in some abstruse problem. The sea was smooth, but dark clouds, edged with bright, copper-tinted hues, were rapidly banking up against the westerly breeze, while the rumble of distant thunder was heard at frequent intervals. Even though it was close on midday the sun’s light was greatly obscured; while, on the other hand, the far away Sudan coast stood up clearly under the effect of atmospheric refraction. There was every indication of a sharp yet severe storm. "Are you going to submerge her, Devoran?" asked the sub.