The constrictor knot is one of the most effective binding knots. Simple and secure, it is a harsh knot that can be difficult or impossible to untie once tightened. It is made similarly to a clove hitch but with one end passed under the other, forming an overhand knot under a riding turn. The double constrictor knot is an even more robust variation that features two riding turns. History First called "constrictor knot" in Clifford Ashley's 1944 work The Ashley Book of Knots, this knot likely dates back much further. Although Ashley seemed to imply that he had invented the constrictor knot over 25 years before publishing The Ashley Book of Knots, research indicates that he was not its only originator, but his Book of Knots does seem to be the source of subsequent knowledge and awareness of the knot. Although the description is not entirely without ambiguity, the constrictor knot is thought to have appeared under the name "gunner's knot" in the 1866 work The Book of Knots, written under the pseudonym Tom Bowling. The knot is described in relation to the clove hitch, which he illustrated and called the "builder's knot". He wrote, "The Gunner's knot (of which we do not give a diagram) only differs from the builder's knot, by the ends of the cords being simply knotted before being brought from under the loop which crosses them." But Bowling is simply an extraction and translation of the knotting work contained in the huge French , first published in 1841, which says "" When J. T. Burgess copied from Bowling, he changed this text to merely state "when the ends are knotted, the builder's knot becomes the gunner's Knot." Although a clove hitch with knotted ends is a workable binding knot, Burgess was not actually describing the constrictor knot. In 1917, A. Hyatt Verrill illustrated Burgess's clove hitch variation in Knots, Splices and Rope Work. The constrictor knot was clearly described but not pictured as the "" ("timber knot") in the 1916 (2nd) edition of the Swedish book ("On Knots") by Hjalmar Öhrvall. Finnish scout leader Martta Ropponen presented the knot in her 1931 scouting handbook ("Knot Book"), one of the first published works known to contain an illustration of the constrictor knot. Cyrus L. Day relates that, "she had never seen it in Finland, she wrote to me in 1954, but had learned about it from