Colliery checks and tokens
One of the non-technological but highly efficient visual communication systems were colliery check systems. These became common during the late nineteenth century and informed management as to who was working underground at any point in time. Additionally, the check system became vital when rescue services needed to know how many men were trapped underground in case of an emergency like roof falls or fire.
Early systems usually consisted of one single check or token per worker. At the beginning of a shift, the worker handed his numbered token to the lamp man who, in exchange, handed the worker a safety lamp with the corresponding number. At the end of a shift, the worker trades the safety lamp back for his token and takes it home until his next shift (Thompson, 2013).
Just like other communications systems, check systems also developed over time and by the late 1970s a three check system (safety check system) became common. In this system the initial lamp token was replenished by two additional tokens – one that was handed to the banksman before descending the shaft and one that the worker kept with him during the shift.
Tokens were typically coined with a number as well as the mining company’s name and existed in a variety of different shapes, sizes, colours, and materials (Thompson, 2013).