spurling-line

from The Century Dictionary.

• noun Nautical: A line connected with the axis of a wheel by which a telltale or index is made to show the position of the helm.
• noun A rope stretched across between the two forward shrouds, having thimbles spliced into it to serve as fair-leaders for the running rigging.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Naut.) The line which forms the communication between the steering wheel and the telltale.