At different points in its lifetime it is known as the Time Machine, the Soul Exchanger (or Soul Swapper), and the Unlimited Energy Device (or Unlimited Energy Machine).
In the 1880s Zackariah Webb built the machine in his laboratory in the Webb Mansion. He had attempted to build a Time Machine, but at first the machine only worked halfway, killing the test subjects. Webb was testing the process on animals, and so lost a number of test animals and pets (among them a budgie and a cat).
In 1886 (possibly on 23.08.), Webb did another trial of the machine, but this time the machine simply disappeared, leaving the test animal, a dog, unaffected.
Gaining a cult
The machine had in fact traveled through time, to its future, landing in the 1960s. At that point, the abandoned Webb Mansion was inhabited by a group of hippie squatters. They found the machine, and believing it to be a cosmic gift, formed a cult around it (later naming themselves the Men of the Machine).
At some point the Men of the Machine figured out how to use the machine to swap souls and bodies, now calling the machine the Soul Exchanger.
At first the cult soulswapped into animals as a spiritual experience, but moved on to soulswapping with other humans, using the identity theft for personal gains and to amass wealth, power and influence for the cult and its members.
The cult became aware of Webb's (now "Edgar Spring") Unlimited Energy Device, which they demanded from him. This started the open struggle between Webb and the Men of the Machine, with each wanting to acquire the other's machine.
A Completely Lost Dog
The machine was brought to the socket under the Spring Mansion and used to soulswap Lydia and Rapunzel, returning each to their original bodies. The machine was fixed by Ken into a properly working time machine. The destination date tube provided by 2001!Patrick Spring and a note written by Dirk were put into the machine, and then the machine was sent back to 1886, the date it had first traveled through time.
Back with its creator
Moments after the time machine had originally disappeared in Webb's laboratory in 1886, the Soul Exchanger reappeared (back from the future year 2016). Webb took in the altered appearance -- aged and covered in occult symbols -- and read Dirk's note, finding that things had gone very wrong.
Webb used the reappeared machine to travel from 1886 to 1968, intending to fix everything. He arrived in the Webb Mansion and confronted the cult in its early days, demanding back the machine. They refused to give it up to him, starting Webb's long struggle to take it back.
Forced to stay in the future, Webb figured out how to use his machine to create energy, which is how it became the Unlimited Energy Device. He created the identity of Edgar Spring for himself and moved into the Ridgely building in Springsborough, housing his machine in a room under the Ridgely. In 1978, Edgar buried his own power grid in Springsborough and used the machine to power that part of the city until the mid-1990s.
During his time as Edgar he used the machine to make small jumps forward.
Arriving on 03.08.2016, Patrick murdered a large number of cultists, and also accidentally caused the death of his own future self. After having learned and seen all the details of the whole, tragic story around his life and the machine, Patrick decided to return to the past and let history play out as it did. He told Dirk and Todd to save his daughter Lydia Spring, and provided them with the knowledge and tool to send their machine back to him to close the loop.
Patrick Spring returned back to 2001, and disassembled the machine and buried its parts in several places in Skagit Valley. He left a map to the locations in a room under the Ridgely building, found and accessed though a trail of clues and a deadly maze of riddles.
On the 10.08.2016, they took the machine back to Seattle, where it was taken by the Men of the Machine when they were captured and brought to the Animal Transfer Unit. There Dirk figured out the true nature of the machine -- that all three involved machines were in fact one machine going though a time loop. Dirk and Todd used it to flee their captive situation by traveling back in time by one week.
After less than a day in the past, they used it to return to the future, their present, moments after they had initially left. There the machine was destroyed when it was shot by Detective Estevez as he stormed the ATU.
To be used the machine was plugged into a socket podium (also called "plug"). Several such sockets existed, one in the Laboratory of Zackariah Webb under the Webb Mansion, one in a room under the Ridgely building, and a different one in possession of the Men of the Machine at the Animal Transfer Unit.
The machine was activated by turning a crank inserted in the socket. The crank was deposited in the basement laboratory in the Spring Mansion, and could also be used to open and enter the Springsborough death maze, and reactivate the screen array at the maze's end.
In the machine was a row of three plugs for temporal destination tubes, which looked like lightbulbs. A tube could be pre-programmed with a time and date the time machine was supposed to travel to. On the UED, the date showed up in a corresponding digital number display at the front of the machine, in the format "MM DD YY".
The machine has been used in several functions over the years.
Time Machine: Webb created it to be a time machine. At first it malfunctioned, working only half-way: it only sent a being's energy, their soul, through time but left their body behind. As this separated the soul from the body, the process effectively killed the test subjects, whose souls reappeared out of their time jumps briefly as energy ghosts before dissipating.
Then one day the machine spontaneously did travel to the future, but just by itself.
Decades later it was fixed by Ken, restoring it to its full capabilities as a time machine. The fully functional time machine could jump through time and take beings or objects with it, depositing them in the same place in the chosen future or past. The temporal destination of a jump was controlled through tubes that were pre-programmed with the travel date, and which could be plugged into the machine.
Soul Exchanger (or Soul Swapper): Used to swap souls between bodies. This made use of the half-working time travel function of the machine. Two beings could be applied to the machine at the same time, sending their souls moments into the future and leaving their bodies empty. In the interval, the bodies were exchanged for one another, so that when the souls arrived from moments in the past, they would reappear in the same space which was now occupied by a different empty body. Thus the reappearing soul would enter the new body and inhabit it.
Swapped souls seem to have had the capability to appear outside their bodies in certain circumstances. One case was Lydia Spring projecting her human face and voice outside of the dog body she inhabited when threatened with falling off Eastgate Bridge. The other case was the Kitten-Shark manifesting its shark soul outside of its cat body, capable of causing real physical harm; this happened on two occasions, both times when the kitten was thrown in the air.
Souls could also be put and endure in inanimate objects in some form. The soul of Pepe the rhino was placed by its owner Patrick Spring into a door in the Springsborough maze.
Unlimited Energy Device
Unlimited Energy Device (or Unlimited Energy Machine) was used to create energy, which Spring used to power electrical grids and machinery.
Behind the scenes
- In the show bible, the aspects of the machine were called the "Time Machine", the "Autexious Soul Exchanger", and the "Unified Cycle Device".
- The UED when unearthed by Dirk and Todd showed three dates on its displays as Farah switched them on: 08 03 16, 07 17 01, 08 23 96. Before time traveling away, the dates displayed were 08 03 16, 08 10 16, 08 03 16.
- The first batch of dates are Patick Spring's death (03.08.2016), Catherine Spring's death (17.07.2001), and an unexplained date (23.08.'96).
- The 23.08.'96 date might be the day of the initial first time travel (if it's really 23.08.1886 and '96 is a production error), or it might be an undescribed travel date or event in 1996 or 1896.
- The date 10.08.2016 is the day Dirk and Todd travel away and then back to during their trip to Day 1.