In the 18th century, the British Royal Navy used the term bark for a nondescript vessel that did not fit any of its usual categories. Thus, when the British admiralty purchased a collier for use by James Cook in his journey of exploration, she was registered as HM Bark Endeavour to distinguish her from another Endeavour, a sloop already in service at the time. She happened to be a ship-rigged sailing vessel with a plain bluff bow and a full stern with windows.