Noiselessly we slipped closer and closer in our exciting chase. The main thing was that our periscope should not be observed, or the steamer might change her course at the last moment and escape us. Very cautiously, I stuck just the tip of the periscope above the surface at intervals of a few minutes, took the position of the steamer in a second and, like a flash, pulled it down again. That second was sufficient for me to see what I wanted to see. The steamer was to starboard and was heading at a good speed across our bows. To judge from the foaming waves which were cut off from the bow, I calculated that her speed must be about sixteen knots.
The hunter knows how important it is to have a knowledge of the speed at which his prey is moving. He can calculate the speed a little closer when it is a wounded hare than when it is one which in flight rushes past at high speed.
It was only necessary for me, therefore, to calculate the speed of the ship for which a sailor has an experienced eye. I then plotted the exact angle we needed. I measured this by a scale which had been placed above the sights of the periscope. Now I only had to let the steamer come along until it had reached the zero point on the periscope and fire the torpedo, which then must strike its mark.
You see, it is very plain; I estimate the speed of the boat, aim with the periscope and fire at the right moment.
He who wishes to know about this or anything else in this connection should join the navy, or if he is not able to do so, send us his son or brother or nephew.
VI--SCENE OF TERROR AS THE SHIP GOES DOWN
On the occasion in question everything went as calculated. The steamer could not see our cautious and hardly-shown periscope and continued unconcerned on its course. The diving rudder in the "Centrale" worked well and greatly facilitated my unobserved approach. I could clearly distinguish the various objects on board, and saw the giant steamer at a very short distance--how the captain was walking back and forth on the bridge with a short pipe in his mouth, how the crew was scrubbing the forward deck. I saw with amazement--a shiver went through me--a long line of compartments of wood spread over the entire deck, out of which were sticking black and brown horse heads and necks.