(Image: Meissner, Philpott, and Philpott)
People with impaired hearing may use sign language. But so may people who can normally hear, but are in noisy environments, like an industrial workplace.
In a fascinating article at Altas Obscura, Sarah Laskow describes a sign language that developed among the sawmill workers of British Columbia. It was an elaborate language that could, beyond the practicalities of sawmill work, convey insults, profanities, and relationships.
In the chart above, 125 expresses "weak." 126 means "What time is it?" 128 means "woman." Laskow writes:
The researchers witnessed a sign language system complete enough that workers could call each other “you crazy old farmer,” tell a colleague that he was “full of crap,” or tell each other when the foreman was “f*&%$@& [profanity edited] around over there.” […]
The core of the sawmill workers’ sign language was a system of numbers, standardized across the industry. Those signs were shared in a technical notebook, and, the linguists wrote,”in the view of the management, that was about all there was to the language.” But it covered much more ground than technical communication. Workers could talk about quitting time, lunch time, and cigarette breaks. They could talk about sports and the bets they placed on games. They could talk about their wives, cars, and colleagues. They could tell jokes and comment on what was going on around them without their bosses ever knowing.
These industrial languages were fading by the 1950s and appear to be extinct now.
-via Marginal Revolution