A cord used by a passenger in a carriage to signal to the driver to slow down or go faster.
1864,, William Stephens Hayward, Revelations of a Lady Detective, short story "Incognito", George Vickers, Strand
I pulled the check-string, and gave him [the coachdriver] his instructions.
Mrs Hurstpierpoint - the dowager of the gleaming brows - leaned forward all at once in the carriage and pulled the checkstring attached to her footman's arm.
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