Page:Polar Exploration - Bruce - 1911.djvu/60

56 and adhering to each other the slush becomes a plastic crust on the surface, even less than an inch thick. This newly-formed sheet of ice is known as "Bay ice," because naturally it forms more easily in sheltered bays. Any new ice, from the thinnest film to ice of, say, 6 to 8 inches in thickness, is termed "Bay ice." An ordinary wooden ice ship forges its way through it by continuously steaming ahead. Until this bay ice is some 4 or 5 inches thick it has a black appearance, being more or less translucent. But when it becomes thicker and more securely frozen together with some sharp frost it becomes whiter.

A ship steaming through "Black ice" cuts through it as through a sticky scum, leaving a blacker lane of water astern, exactly the width of the ship, which does not close up until frozen over again. But through the thicker and more rigid "White ice" as the ship steams ahead a long split is formed ahead of her, through which she is able to forge her way. This more completely formed white ice is often easier for navigating a ship through, because it is more brittle than the thinner black ice, which is gluey in texture.

Now, if the water remain calm very striking and beautiful developments occur. There is always some horizontal motion in the surface of the sea, even if it is a glassy calm, owing to