Detroit Adder from Standard Computing Scale Co. (ca.1902)

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Dating back to the end of the 19th century, this mechanical adder was patented in 1902, showcasing impressive innovation for its time. With dimensions of 180mm diameter and 10mm thickness, it operates by moving discs using a pointer inserted into holes and rotating lower discs clockwise until the zero cotter is reached. The internal mechanism accounts for carries from hundreds to inner digits when 100 is surpassed. This device allows addition of up to 999.999, comprising three groups of two-digit numbers; however, it doesn't support subtraction. To obtain the full model, inquire via email as the compressed file size is approximately 100MB. Note that springs are not included in the digital representation and there are seven in total.