The owner of the voice replied:  ‘You have no torpedoes?’

’We have only the armament agreed upon by you to protect this immense mass of bullion from the attacks of the unscrupulous,’ said Mr. Macrae.  ’I take heaven to witness that I am honourably observing every article of our agreement, as per yours of August 21.’

‘All right,’ answered the voice.  ’I dare say you are honest.  But I may as well tell you this, that while passing under your yacht we attached two slabs of gun-cotton to her keel.  The knob connected with them is under my hand.  We placed them where they are, not necessarily for publication—­explosion, I mean—­but merely as a guarantee of good faith.  You understand?’

‘Perfectly,’ said Mr. Macrae, ’though I regard your proceeding as a fresh and unmerited insult.’

‘Merely a precaution usual in business,’ said the voice.  ‘And now,’ it went on, ’for the main transaction.  You will lower your gold into boats, row it across, and land it here on my deck.  When it is all there, and has been inspected by me, you will send one boat rowed by two men only, into which Miss Macrae shall be placed and sent back to you.  When that has been done we shall part, I hope, on friendly terms and with mutual respect.’

‘Captain McClosky,’ said Mr. Macrae, ’will you kindly pipe all hands on board to discharge cargo?’ The captain obeyed.

Mr. Macrae turned to Bude.  ‘This is a moment,’ he said, ’which tries a father’s heart!  Presently I must see Emmeline, hear her voice, clasp her to my breast.’  Bude mutely wrung the hand of the millionaire, and turned away to conceal his emotion.  Seldom, perhaps never, has a father purchased back an only and beloved child at such a cost as Mr. Macrae was now paying without a murmur.

The boats of the Flora Macdonald were lowered and manned, the winches slowly swung each huge box of the precious metal aboard the boats.  Mr. Macrae entrusted the keys of the gold-chests to his officers.

‘Remember,’ cried the voice from the submarine, ’we must have the gold on board, inspected, and weighed, before we return Miss Macrae.’

‘Mean to the last,’ whispered the millionaire to the earl; but aloud he only said, ’Very well; I regret, for your own sake, your suspicious character, but, in the circumstances, I have no choice.’

To Bude he added:  ’This is terrible!  When he has secured the bullion he may submerge his submarine and go off without returning my daughter.’

This was so manifestly true that Bude could only shake his head and mutter something about ‘honour among thieves.’

The crew got the gold on board the boats, and, after several journeys, had the boxes piled on the deck of the submarine.

When they had placed the boxes on board they again retired, and one of the men of the submarine, who seemed to be in command, and wore a mask, coolly weighed the glittering metal on the deck, returning each package, after weighing and inspection, to its coffer.  The process was long and tedious; at length it was completed.