A careful watch was maintained along the shore, the coastguards stationed in the district being temporarily augmented by men drafted from more remote places. Yet no trace of the mysterious submarine on the surface was to be seen. How, when and where the craft replenished her fuel necessary for locomotion purposes and her provisions and fresh water completely baffled the naval experts; for a fortnight had elapsed since she announced her appearance at Spithead, and save for the temporary visit to Cherbourg all evidence pointed to the fact that she was still within the limits of the Port of Portsmouth. Arnold Hythe duly joined the "Investigator" as officer in charge of the diving parties. Twelve first-class seamen-divers were drafted into the ship, while special gear for "creeping" was placed on board. Submarine apparatus for recording by sound the presence of submerged craft under way was also installed, so that it was impossible for any vessel making the faintest noise to approach within two miles of the "Investigator." Even the wavelets lapping the bows of a passing fishing-smack would be reproduced with unerring fidelity. Just before high water the "Investigator" was undocked; steam was soon raised, for the surveying vessel, being of an old type, was driven by reciprocating engines and oil-fed boilers. Almost at the moment of casting off the hawsers and springs came news that caused the greatest disappointment amongst officers and crew. Captain Restronguet had, according to the latest report, turned up in a totally different spot. This time he devoted his attention to the German port of Wilhelmshaven. Here his visit was not of a comparatively harmless nature, for the locks of the Kaiser Wilhelm Canal were totally demolished by means of a powerful explosive. The battleship, "Karl Adelbert," that was about to pass out of the canal, was badly damaged. In the confusion six destroyers and submarines were ordered from Cuxhaven. They were quickly on the spot, but no trace of the mysterious submarine was to be seen, except a small barrel painted white and green, with the name "Captain Restronguet" in bold letters. The "Investigator" was immediately ordered to make fast one of the buoys in Portsmouth harbour. Her special mission was, for the time being at least, over; a far more serious situation had arisen. The German Government, supported almost entirely by the Press of that country, actually suggested that, since Captain Restronguet had committed an act of piracy against the German Fleet while he had refrained from so doing on his visit to Portsmouth and Cherbourg, Great Britain and France were secretly aware of the identity of this modern buccaneer, and that they had encouraged him to make an unlawful act of hostility towards a friendly Power.