The English soon discovered how we arranged these explosions, and the guards carefully inspected the lines each day to find out if one of these machines had been placed beneath the rails.

We knew that one had been found and removed, whenever we saw a train pass over the spot without being blown up.

This, however, only made us more careful.

We went to the spot which we had fixed upon for the explosion, hollowed out the gravel, placed the machine under the sleeper, and covered it up again, throwing the gravel that was left to a good distance from the line.

After this, the guards could not discover where the machine was placed.