Hired Girl prototype

The Hired Girl prototype was the first working model of Dan Davis’s household automaton and the practical proof behind the company that bore its name. Built from existing mechanisms rather than a single unprecedented invention, it embodied the novel’s insistence that engineering depends on assembling available technologies—and making the result affordable and useful.

Design and Operating Principle

Davis described the machine’s brain as a deliberately limited one: it needed to be a docile, repetitive worker, not a human mind. A Thorsen tube could record an operation performed under manual control and repeat it without supervision. Side circuits searched for specified conditions and interrupted the stored routine when circumstances did not match, a rudimentary mechanism Davis distinguished from genuine judgment. In his account, a machine could not possess judgment; its apparent discretion was a programmed hunting circuit.

That design gave the automaton a practical route from demonstration to routine. A user could guide it through clearing a table, scraping dishes, and loading a dishwasher once, after which the recorded sequence could handle later loads. Davis also envisioned duplicating the tube electronically so that a machine could manage dirty dishes on first encountering them without breaking one. The prototype thus stood for an approach to domestic automation based on recorded procedures and constrained responses rather than humanlike intelligence.

Construction and Production

The design drew on a range of prior devices. Davis adapted a basic search pattern from the “Electric Turtles” described in Scientific American, took a memory circuit from a guided missile, and combined cleaning mechanisms and linkages from equipment including a hospital floor polisher, a soft-drink dispenser, and the remote “hands” used to handle radioactive materials. His account locates the invention in the arrangement of these parts; the legally required “spark of genius,” he wryly observed, lay in obtaining a good patent lawyer.

Manufacturing made that arrangement commercially consequential. Most components could be ordered from Sweet’s Catalogue; only two three-dimensional cams and one printed circuit departed from standard parts. Davis made the cams himself in a shed used as a factory, with war-surplus automated tools, while the circuit was subcontracted. He and Miles Gentry initially assembled the machines themselves, fitting, filing, and painting the parts. The pilot model cost $4,317.09, while the first hundred cost a little over $39 apiece. Sold on consignment to a Los Angeles discount house for $60, they retailed for $85; a two-page feature in Life helped bring the demand and staffing needed to expand assembly.

The Prototype and Its Maker

Years later, Jack Galloway arranged for Davis to be photographed with the very first model of Hired Girl. Davis recognized the machine as the one he had assembled with his own hands and recalled the sweat that had gone into it. He wanted to see whether it still worked, but McBee would not let him start it, apparently unconvinced that Davis knew how it operated. The encounter placed the surviving object between its maker’s intimate technical knowledge and a company that now controlled access to it.

The visit nevertheless returned Davis to the professional world of engineering. During March and April he had access to tools, journals, trade catalogues, a practical library, and a Drafting Dan made by Aladdin, since Hired Girl did not manufacture drafting machines. The prototype was no longer simply a machine in a shed: it had become the remembered origin of a mature enterprise, even as Davis found himself unable to demonstrate its operation.

Later Designs and Significance

After returning to 1970, Davis built Drafting Dan before rebuilding Flexible Frank, because the old compass-and-T-square method wasted time. He renamed the redesigned general-purpose automaton Protean Pete, intending its patent claims to cover a machine capable of doing nearly anything a person could do if properly instructed by its Thorsen tubes. He expected later generations to develop into specialized devices. This subsequent work makes the Hired Girl prototype an early point in a continuing engineering trajectory: from a focused household cleaner to a more adaptable platform, and from a working machine to a family of applications.

The prototype’s importance is therefore inseparable from constraints as well as ingenuity. Davis later explained that he had not voice-coded the first Flexible Frank because the analyzer and telephone exchange would have outweighed, enlarged, and cost more than the rest of the machine combined. He needed further advances in miniaturization before that feature was practical. The Hired Girl prototype records the same principle at the heart of its success: invention becomes useful not through imagination alone, but when available components, production methods, and the state of the art meet a real task.