About 2,000 years ago, a physician used the lark’s head to tie a sling for broken bones. Today this knot secures such things as baggage tags. Not used for much aboard ship, the knot will slip unless both the bitter end and the working part are both under tension.
Begin with an underhand loop followed by an overhand loop, with the tip of each loop up. Hold the line with both hands, and fold the loops together, like closing a book.
B. Slip the loops over the open end of the spar and pull the two ends down through the loops. If the loops can't be slipped over the end of the spar, take the bitter end of the line over the spar, go around and in back of the working part, back over the spar, and back down through the bight parallel to the working part.
Original materials used with thanks to Irene Rodriguez and John Bennett