By six o'clock in the afternoon the Olivette had traversed four and a half kilometres of the canal, and had tied up for the night close to a "cut" leading to the town of Harfleur.

"We must see the sights of Harfleur," declared Mr. Armitage. "It is only a little town, but it's full of interest. You remember, perhaps, how it was besieged and captured by Henry V before he won the Battle of Agincourt."

Accordingly the dinghy was launched and manned. It was the first time the little craft had been used since the Olivette left Keyhaven, and even then, it was not absolutely necessary. The Sea Scouts could have landed and walked along the canal bank.

It was dark by the time they returned. Tom Boldrigg had lighted the cabin lamps, and had prepared supper. Eagerly, the hungry lads sat down to enjoy what promised to be an appetizing repast, but their anticipated pleasure failed in its realization.

The Olivette was invaded. Thousands of little green flies swarmed everywhere. The lamp glasses were thick with them; so much so, that in spite of frequent cleaning, the light was almost entirely obscured by the writhing insects. These covered the table, settled on the food and in the hot cocoa. In the circumstances, making a meal was out of the question.

"It's the light that does it," declared Boldrigg. "Put out the light an' the midges'll sheer off."

This suggestion was acted upon. In addition, the Olivette's riding lamp was hoisted to attract the flies. The result justified the experiment. As if by magic, the insects disappeared, leaving hundreds of small corpses in the cabin. Hungry, the crew had to make a sorry meal in the darkness, munching hard biscuits and trusting to luck that they were not swallowing dead flies; and in darkness, too, they sought their bunks.

At six the following morning, the "hands" were roused in true nautical style. It was a glorious morning, and the waters of the canal looked temptingly clean and fresh. Soon all the crew were swimming about, and so thoroughly did they enjoy it, that Mr. Armitage had difficulty in getting them to come out of the water.

Before breakfast could be served, Roche and Flemming had to walk into Harfleur to obtain fresh provisions, for everything of an edible nature on board had been spoiled by the flies.

While the two Sea Scouts were away on their errand the rest cleaned ship thoroughly, all hands hoping that a repetition of the visitation would not occur on the following night.