Cable Tow 

This term is used in Freemasonry to indicate a distance of Three Miles from the location of the Lodge.  If a Mason receives a summons to attend a Lodge Meeting and that Lodge is within a distance of a Cable Tow, he is obligated to attend such meeting unless prevented by sickness or some other unavoidable occurrence.

I assume that the term Mile refers to the Statute Mile of 5280 feet.  I am not sure on this.

The Cable Tow has been said to be the scope of a brother's reasonable ability in length.

Perhaps the term cam from the German term 'Kable tau' said to have meant a cable rope. 

Symbolically like the umbilical cord attaching the unborn to his mother the cable tow connects the Mason to his Lodge.