Thorsen tube

The Thorsen tube is the programmable component that makes Dan Davis’s automata adaptable: a machine’s abilities depend on how its tubes are instructed, while adding more tubes expands what it can learn. In Protean Pete, this principle supports both a deliberately broad commercial design and the later extension of automation into household work.

Definition and Operation

Davis describes Thorsen tubes as components that must be properly instructed for an automaton to perform its tasks. Protean Pete can do almost anything a man can do, but that capacity is conditional: the tubes have to be taught what to do. The tube therefore represents not a single fixed function but the programmable basis for a range of functions.

The distinction between a machine’s potential and its instruction matters in practice. When asked about dishwashing, Davis explains that the task involves many alternate choices and requires several hours of programming; unlike a comparatively simple routine such as laying bricks or driving a truck, it is a judgment job. Once taught, however, Pete can perform it thereafter. The tubes accommodate judgment-intensive work, but only through deliberate instruction.

Design and Commercial Purpose

In 1970, Davis builds Drafting Dan first because designing with a compass and T-square is tedious and he has no time to spare. He then rebuilds Flexible Frank as Protean Pete, an all-purpose automaton whose many linked capacities depend on its Thorsen tubes. Davis knows that Pete’s descendants will eventually evolve into specialized gadgets, yet he wants the patent claims to be as broad as possible. The design thus joins immediate utility to a wider commercial ambition: one adaptable machine establishes the scope from which later specialized devices can develop.

The tubes are part of a larger engineering and sales strategy, not merely a technical feature. Davis wants working models that can be demonstrated reliably and that show their practicality and the economy of their eventual production engineering. Their capabilities must make a persuasive case that the machines work and are commercially worthwhile. The tubes enable breadth of function; the finished model must make that breadth legible as an investment.

Household Use and Significance

Pete’s capabilities initially serve Davis’s plans for commercial work: he is engrossed in teaching the machine to perform jobs for other people and overlooks the possibility of putting it to work for himself. Jenny’s remark that Davis has been living like a pig prompts him to begin teaching Pete the household tasks Flexible Frank had learned. Pete has three times as many Thorsen tubes as Frank, giving him greater capacity for this expanded role. The technical feature that supports an ambitious multipurpose product also makes domestic assistance possible.

That shift gives the Thorsen tube its significance beyond mechanical flexibility. Household labor, including dishwashing, is presented as complex work involving choices rather than as a simple repetitive routine. Pete does not arrive already knowing how to do it: Davis has to program him, and the process takes time. But instruction converts that complexity into a reusable capability. The tubes make automation a learned, extensible practice—one that can free time at home as well as supply machines for commercial tasks.

Connection to Time Displacement

The novel’s time-travel thought experiment applies the same tube to a different kind of extension. Davis asks Ricky to imagine a speckled guinea pig sent back a week in a time cage, where an earlier version of the same animal has already been found; for a time, two versions appear to exist, though Davis insists they are one animal at different ages. In this hypothetical, the Thorsen tube belongs to the mechanism that sends the guinea pig backward. Its appearance connects programmable automation with the novel’s account of time displacement, while the example frames temporal paradox as a problem of identity and chronology rather than the creation of a second independent animal.