Double D, if moconfed is using the terms of the 19th century, he is correct. Back in those days the size of a rope, Army rope, was specified in terms of it's circumference, not it's diameter like today. A Garrison Gin used a 5" rope; today this would be (1.60") and the prolong used a 3", a little less than one inch in today's size, (.950"). Divide by pi.
Tracy