Now in late winter the surface of Robeson Channel was covered by a solid, unmoving pack, but the cold was so intense that it could be endured in the field only by men of iron. Day after day the temperature was eighty degrees below the freezing-point, and even when it should moderate the travelling party must be carefully chosen. Rawson was to go as a passenger, for his ship was the _Discovery_ to which he was now to return. Of all available officers Egerton seemed to have physical and mental qualities that promised well. Naturally the dog driver--for they were to travel with a dog-sledge--would have been Eskimo Frederick. In this emergency Niels Christian Petersen offered his services, claiming that his arctic experiences and powers of endurance fitted him for such a journey. A Dane by birth, his years of service in Greenland had made him a skilled dog driver, and experiences with Dr. Hayes in his expedition of 1860 had made him familiar with field service. A vigorous man of forty years, he seemed the best of the three sledgemen for stanch endurance in such ice and weather. Nares said in his letter of instructions: "In performing this duty in the present cold weather, with the temperature more than seventy-seven degrees below freezing, great caution is necessary." The date of departure was originally fixed for March 4, 1876, the day on which the retiring sun was first clearly seen above the southern hills at 11.30 A. M. The cold was intense, being one hundred and one degrees below the freezing-point. Whiskey placed on the floe froze hard in a few minutes. Egerton's departure was therefore postponed until the prolonged cold ended eight days later. Meantime it was clear that such awful temperatures would seriously affect the dogs, who were suffering in short exercise marches from the action of the intense cold on the sharp, sand-like snow particles--all separate. Nares relates that in crossing the trails of the dogs near the ship he "noticed, lying on the floe, numerous frozen pellets of blood which always form between the toes of these animals when working during severely cold weather. The heat of the foot causes the snow to ball; this soon changes into ice, and collecting between the toes cuts into the flesh. On board of the _Resolute_ in 1853 we endeavored to fit our dogs with blanket pads on their feet, but these were found to increase the mischief by first becoming damp and then freezing, when the hardened blanket cut into the sinews at the back of the dogs' legs."[16] On March 12, 1876, Petersen threw forward the long flexible lash of his Eskimo whip, calling sharply to the waiting dogs, and the party dashed off in a temperature of minus thirty degrees. Petersen, Rawson, and Egerton took turns on the sledge, one riding at a time. The others ran behind the sledge, holding fast each to one of the upstanders.[17]