Before Sefton could reply he was called away. A Zeppelin had been sighted, flying in the direction of the badly mauled Calder.
Quickly the remaining gun was manned. Although not intended for aerial work, modification to the original mounting permitted it to be trained within ten degrees of the perpendicular, supplementary sights having been fitted to enable it to be laid while at extreme elevation.
The air-ship was still four miles off, and flying at an altitude of about 2000 feet. Apparently undamaged, it was proceeding at a rapid pace against the wind.
Deprived of the advantage of speed and manoeuvring powers, the destroyer would fall an easy prey to the Zeppelin's bombs unless the Calder could make good use of her solitary 4-inch quick-firer. The weapon was loaded and trained abeam, the gun's crew being ordered to take cover, and thus give the destroyer the appearance of being incapable of defence.
Sefton made no attempt to alter helm. He had made up his mind to wait until the huge target came within easy range. He knew that the Calder was under observation, and that the Germans were trying to ascertain the nature of the destroyer's injuries. Should they come to the conclusion that the slowly-moving British craft was powerless of doing damage they would not be likely to waste ballast in ascending to a safe altitude and a corresponding loss of hydrogen in descending after the attack.
Nearer and nearer came the huge air-ship, her bows steadily pointing in the direction of the destroyer. Range-finder in hand, Sefton curbed his impatience. Not until the Zeppelin bore at a distance of 2500 yards did he order the gun's crew to their stations.
With a vicious spurt of flame and a sharp, resounding detonation the 4-inch sent a shell hurtling through the air. Admirably timed, it burst apparently close to the silvery-grey envelope. Almost instantly a huge cloud of black and yellow smoke shot from the Zeppelin.
A rousing cheer burst from the throats of the British seamen. The cheer was taken up by the wounded heroes down below, who, having heard in some mysterious manner of the air-ship's approach, were waiting the issue of events with mingled confidence and regret that they themselves were unable to assist in "strafing the sausage".
The cheers literally froze on the lips of the men on deck, for when the smoke cleared away the Zeppelin was a mere speck, 10,000 feet in the air. Under cover of a discharge of smoke she had dropped a large quantity of ballast and had shot vertically upwards to a safe altitude.
The Hun in command had received orders not to attack unless he could do so without risk, the Zeppelin being specially detailed for observation work. With a range of visibility of fifty or sixty miles she was of far more service to the discomfited German High Seas Fleet in warning them of the position of their victors than in strafing a solitary destroyer.