The United States version of the Time Tunnel was built in 1958. ("Rendezvous with Yesterday") One of the lead scientists of the project, Dr. Doug Phillips, first envisioned that the Time Tunnel would have a capsule developed and work in conjunction with the Tunnel, which housed up to two time travelers so they could be transported to another place and time. However, the capsule turned out to be a failure (and fatal), which it was replaced by a radiation bath that people must pass through first in order to travel through time. ("Secret Weapon")