Manjack Explained:
At the start of the industrial revolution wooden pulleys and rope rigging were very common along with mule, water, wind or man powered mechanisms for operating mills and the very earliest automated looms. It would still be a while until steam power pushed the industry to new heights and pharmaceutical chemists discovered a whole range of new chemicals, however medical technology was moving ahead with the rediscovery of honey as an antiseptic. it had been used for thousands of years prior but a century or two ago had been denounced as witchcraft or superstition, despite the fact it clearly worked and without and help from magic.

Now that the microscope had been invented, scientists could prove that honey killed the bacteria that caused infection however, so scientists claimed it as their own discovery and used it in a medical background. Medicine until now consisted of cutting boils out which had often lead to an infection that also needed to cut out that lead to an infection etc. etc. in a vicious cycle that often resulted in infection spreading to the organs and individual dying of septicemia, often after losing large portions of their limbs from the deadly cycle beforehand.

People who worked with ropes and gears were often subject to losing fingers or breaking the bones in their hands, and to prevent a deadly infection, doctors would amputate the hand entirely, now that infection could be prevented in a medical setting. Often the person who worked the mechanisms would be unable to work in that job afterwards having only one good hand but certain people who had saved up a lot of money bought a prosthetic hand in the form of a hook.

Having a metal hook might have been the most practical option on the face of things but to make a sturdy loop used a large amount of metal which was still fairly expensive in those days with people even stealing nails. It would also have to be weatherproof, as you'd be required to work outside in the rain or often near warm vats of steaming water. Aluminium needed to make stainless steel was very expensive to produce in those days so silver was generally the best option. However silver was also still too expensive for most so a cheaper solution was often needed. Wood was generally a bad idea as if the wood was cut across the grain the hook was likely to break especially when being pulled hard and the hook curved so it was impossible to avoid if cut from a block of wood. Some clever people however decided to grow a mahogany sapling in their garden in a manner that created an omega symbol shape and cut the top and bottom. This meant that the grain went along the shaft and around the loop of the hook making it much stronger.

Factory foreman at the time liked their workers to be heard working but not seen and so many demanded their workers wear tan or brown clothing so as to blend into the furniture. Workers would also wear bandannas to prevent long hair from getting caught in gears. People with hooks for hands and bandannas were often seen loading and unloading ships so the association with that look and pirates was made.

Those who had hooks were dedicated to their jobs and so often developed an almost philosophical understanding of it. This gave rise to the belief that they were part man, part puppet, especially since automatons were a craze at the time, and the belief they had an affinity with inanimate objects developed as a result. Their survival from having amputations was little understood by many so the belief that they were somehow undead became widespread. Though the story of Pinocchio predates the time by a lot, it was very much a part of the rumors. Also stories of automatons being alive helped fuel the myths but this was just due to them being very convincing.

A jack was a handle used to turn a wheel and considered the go-between between a person and a mechanical device or between two devices. That's why an outlet is known as a wall jack. Manjacks were considered to be part man, part jack or handle and the movie The Matrix has multiple references to the Manjack legends, as well as the movie Johnny Pneumonic, which is a modern adaptation one story in particular.