of technical innovations made the job easier and safer. A pump was built to push fresh air along the ducting, invented by Squadron Leader Bob Nelson of 37 Squadron. The pumps were built of odd items including pieces from the beds, hockey sticks and knapsacks, as well as the Klim tins. The usual method of disposing of sand from all the digging was to scatter it discreetly on the surface. Small pouches made of towels or long underpants were attached inside the prisoners' trousers; as they walked around, the sand could be scattered. Sometimes, they would dump sand into the small gardens they were allowed to tend. As one prisoner turned the soil, another would release sand while they both appeared to be in conversation. The prisoners wore greatcoats to conceal the bulges from the sand, and were referred to as "penguins" because of their supposed resemblance. In sunny months, sand could be carried outside and scattered in blankets used for sun bathing; more than 200 were used to make an estimated 25,000 trips. The Germans were aware that something was going on but failed to discover any of the tunnels until much later. To break up an escape attempt, nineteen of the top suspects were transferred without warning to Stalag VIIIC. Of those, only six had been involved with tunnel construction. One of these, a Canadian called Wally Floody, was actually originally in charge of digging and camouflage before his transfer. Eventually the prisoners felt they could no longer dump sand above ground because the Germans became too efficient at catching them doing it. After "Dick"'s planned exit point was covered by a new camp expansion, the decision was made to start filling it up. As the tunnel's entrance was very well hidden, "Dick" was also used as a storage room for items such as maps, postage stamps, forged travel permits, compasses, and clothing. Some guards cooperated by supplying railway timetables, maps and many official papers so that they could be forged. Some genuine civilian clothes were obtained by bribing German staff with cigarettes, coffee or chocolate. These were used by escaping prisoners to travel from the camp more easily, especially by train. The prisoners ran out of places to hide sand, and snow cover made it impractical to scatter it undetected. Under the seats in the theatre there was a large empty space, but when it was built