that it was necessary to crawl through them; others were as much as five feet high. Some were used for the disposal of rain water, others for waste. (The latter, known as mixed-water channels, were referred to by agents of the Bureau as Glockengasse 4711, after a popular German eau de cologne.) At intervals, all the sewers contained wheel-shaped metal barriers, whose spokes generally extended around the entire circumference of the channel and blocked passage through it. In some rain-water channels, there was a space eighteen or twenty inches high at the bottom of the barrier, which allowed persons of average size to crawl under. Ordinarily, however, the students sawed off one or more of the spokes to allow the Bureau’s clients a more comfortable passage.
The first successful underground route opened by Das Reisebüro ran through a mixed-water channel. The entrance was less than two thousand feet from the eastern side of the wall, and the trip could be made in about half an hour. When the Bureau was arranging an escape, it alerted one of its East Berlin contacts, who notified a certain number of students on the waiting list that they should be in the vicinity of a specified corner at a set time, usually around midnight. They were told to proceed separately to the rendezvous point, and, after arriving, to keep out of sight as much as possible by staying in shadows or by taking cover in the vestibules of buildings. At the appointed time, a Bureau agent appeared and lifted the manhole cover, and, one by one, the students emerged from their hiding places and disappeared into the sewer. They were guided either by one of their own number, who had been briefed on the route and had committed the briefing to memory (“Proceed thirty-two metres straight ahead, take left channel at junction, proceed forty metres to barrier, remove spoke nearest left side of wall, replace spoke . . .”), or, more often, by a Bureau expert who had come from the other side to shepherd the party. After the last student had disappeared, the manhole cover was replaced by a student known as the closer. His task, Heinrich said, was one of the most dangerous parts of the operation. The cover, which weighed a hundred and twenty-five pounds, had to be put back quickly and quietly and without leaving marks. To handle the cover, the closer was given an iron hook, and this implement became a kind of symbolic passport to West Berlin; the rule was that the student who closed the sewer one night was the first to leave the next. When the underground travellers finished their journey, several Bureau agents, including Heinrich, were on hand to greet them. Celebrating, Heinrich told me, was considered “superfluous,” and, for security reasons, was not encouraged. It was strictly forbidden after the Bureau’s original sewer route was discovered because a couple of refugees in one group had not been able to resist letting out a few high-spirited noises upon reaching a point just inside West Berlin. The sounds were heard on the street on the eastern side of the wall by Vopos, who pulled up manhole covers and threw tear-gas bombs into the sewer. That group got through safely, but the route had to be abandoned.
A few days later, the Bureau opened a second route, which was nearly twice as long as the first. It was discovered within a week. The Vopos were now installing new metal barriers, with spokes that would not yield to saws. Though the sewers were becoming increasingly hazardous, the Bureau was able to devise still another route, this one through a rain-water channel in the northern section of the city. It was longer and more circuitous than the others, taking about two hours to traverse, but it was the most successful; on one night three groups totalling thirty-five persons came through it. One young married couple, who were students at the Free University, came through carrying their year-old son in a shopping bag; they had given him a sleeping pill to insure his silence en route. One night, Heinrich said, he was waiting at the exit of the third route when he heard noises b