And then I saw a black speck on the water dead ahead. Involuntarily I shoved down the nose of the boat and opened out the engines. And then I saw that it was the North Hinder. As we passed over her the Dutch flag at her stern was politely dipped in salute. Changing course here we boomed off towards the Schouen Bank buoy on the first arm of the Spider Web.
Suddenly, with a nerve shock, a pleasant tingling which cannot be described, I saw a submarine dead ahead, about five miles away, fully blown, and running directly towards us. Slamming on the engines, and pushing the controls forward so as to lose height and gain the maximum speed quickly, I hurled the 4½-ton machine through the air towards the submarine at a mile and a half a minute.
As our own submarines operated in this area I did not know whether it was a Fritz, but fervently hoped it was.
I noticed that it was running at about six knots, in which case it was probably a Hun travelling on one engine and charging the batteries with the dynamo on the other. The submarine statement received from the Naval authorities the evening before had not mentioned one of our own submarines as working in this vicinity, but then submarines were a law unto themselves as regards time and navigation, and had a habit of appearing in the most unexpected places.
With the opening of the engines, the signal for action stations, the engineer thrust himself up in the rear cockpit and seized the stern guns in case hostile seaplanes had been sighted, the wireless operator quickly wound in his trailing aerial to prevent it being carried away if the boat came down near the water, and Holmes, who had seen the submarine, ducked into the front cockpit. He snapped back the lever which removed the safety device from the bombs and set the bomb-sight for height, speed, and wind.
When a bomb is released it travels forward on the same line as the machine, and, at first, at the same speed, but its speed forward gradually diminishes owing to the resistance of the air. At the same time it travels downwards owing to the force of gravity at an ever increasing rate of speed. It thus reaches the surface of the sea just after the machine has passed vertically over the spot. Therefore a bomb is released some time before the machine is vertically over the target, and this time is determined by the speed of the machine over the sea, the height at which it is flying, and the size, shape, and weight of the bomb. All these factors are worked out on the bomb-sight, and the bomb-dropper has only to pull the release-lever when two projections on the sight and the target are in line.