National Geographic : 1936 Jun
EXPLORING YUKON'S GLACIAL STRONGHOLD LIKE SHIPS OF THE DESERT, SLEDGE DOGS PLOD THE DESOLATE WASTES OF LOWELL GLACIER A surface such as this made excellent sledging, but deep, fresh snow was impossible until the wind, blowing for 36 hours, had packed it to a firm base. Backbone of the expedition was the dogs, which trekked 18 miles day after day through April and May with few rest periods. Each has his own harness "tailored to fit." A strap or trace on each side leads back and is snapped to the harness of the dog behind.