The officer disappeared for some moments, but returned with a pair of binoculars, which he levelled upon the gunboat. The submarine quickly increased her speed, sending up a great fountain of foam as she cut through the water. She passed so close to the shrimp boat that it rocked on the waves she left in her wake. Seth Newruck saw the number on her side—U50. He also caught a glimpse of the face of the young officer on the deck of her conning-tower.
"Look!" he cried excitedly. "Look, sir! It's Max Hilliger himself!"
Hardly had he spoken when there was a spurt of fire and smoke from one of the Kingfisher's 4.7 guns; a shell whistled through the air and sent up a tall column of spray as it fell midway between the submarine and the shrimping boat. The submarine, now fully on the surface and racing along at eighteen-knot speed, offered a good target; but she manoeuvred, steering a zig-zag course, seldom exposing her broadside. A gun was raised from its concealed hatchway on her after platform, and she replied to the Kingfisher's fire without visible effect.
Arnold Bilverstone, nervously gripping the boat's gunwale, was leaning forward, gazing fixedly northward along the coast.
"That's good!" he exclaimed. "There's a couple of destroyers coming out from Buremouth. They'll head her off."
The chase continued. Suddenly the submarine's gun disappeared. The two men on her conning-tower went below. She seemed to be slowing down. A shell from one of the two destroyers fell perilously near her, deluging her with spray.
"She's hit!" cried Seth Newruck. "See! she's sinking!"
"Submerging," corrected Mr. Bilverstone, watching the conning-tower slowly disappear.
The Kingfisher, going at her best speed of twenty knots, was soon abreast of the shrimper, separated by hardly more than fifty yards. Just in time her course was altered; she went abruptly to starboard, and so luckily avoided the torpedo which was aimed at her from the submerged enemy. Seth saw the disturbance of the water as the deadly weapon sped on its fruitless errand.
The gunboat gave up the dangerous chase and steamed a confusing, irregular course until she rounded the southern extremity of Alderwick Shoal, and thus got the protection of the sandbank between her and the submarine. But of the submarine herself and her periscopes no more was seen.