She finds no insuperable difficulty in smashing her way through ice 12 or 13 feet in thickness. The first piece of ice she ever attacked was drift ice about five feet thick, through which she went easily with her engines giving her little more than half-speed. The most serious test was against ice estimated at 25 feet thick, consisting of 5 feet of field ice, 9 feet of pack ice above it, and ice 11 feet thick, and perhaps more, below the field ice. Thick snow on top of thick field ice forms the most serious obstacle, the snow forming an immense cushion or ridge which becomes worse the more an effort is made to get through it. On another occasion she made her way by ramming through ice 34 feet in thickness. Another experience was to rescue eight of nine steamers which were nipped in the ice; the ninth was so badly squeezed by the ice that she sank before the _Ermack_ could force her way to her. A smaller ice-breaker, the _Sampo_, built by the same firm for Finland, has gone through sheet ice 12 inches thick at a speed of 8¹⁄₂ knots, and frequently through drift ice 10 or 12 feet thick. On the other side of the Atlantic, whenever a severe winter is experienced, many of the Canadian and United States lake and coast ports are only kept open by means of ice-breaking ferry-steamers. Of the latter type is the _Scotia_, built by Armstrong, Whitworth and Co. for the carriage of railway trains across the Straits of Canso to and from Port Mulgrave, Nova Scotia. She is 282 feet in length, and on the rails laid on her decks she is capable of taking a load of nine Pullman cars, and can also accommodate an express locomotive and tender weighing as much as 118 tons. She has an ice-breaking propeller and a rudder at each end, and has two sets of triple-expansion engines of 1200 horse-power each. Her speed is rather over twelve knots.