extancy

[W]hereas in ſmall fragments or plates, the Ice, though it ſink not to the bottom of the water, will oftentimes ſink so low in it, as ſcarce to leave any part evidently extant above the ſurface of the water, in vaſt quantities of Ice, that extancy is ſometimes ſo conſpicuous, that Navigators in their Voyages to Iſland, Greenland, and other frozen Regions, complain of meeting with lumps, or rather floating rocks of Ice, as high as their main Maſts.