Task: Question Answering
Input (English): Passage: The party turned for home after 73 days' southward travel. Rations had been cut several times to extend the return journey time beyond the original 110-day estimate. Shackleton now aimed to reach Hut Point in 50 days, since according to Shackleton's prior orders Nimrod, having returned to take the expedition home, would depart on 1 March at the latest. The four men were now much weakened, yet in the following days they achieved impressive distances, reaching the head of the glacier on 19 January. As they began the descent they had five days' food at half rations, to last them until the Lower Glacier depot; during the ascent the same distance had taken 12 days. Shackleton's physical condition was by now a major concern, yet according to Adams "the worse he felt, the harder he pulled".The depot was reached on 28 January. Wild, ill with dysentery, was unable to pull or to eat anything but biscuits, which were in short supply. On 31 January Shackleton forced his own breakfast biscuit on Wild, a gesture that moved Wild to write: "BY GOD I shall never forget. Thousands of pounds would not have bought that one biscuit". A few days later, the rest of the party were struck with severe enteritis, the result of eating tainted pony-meat. But the pace of march had to be maintained; the small amounts of food carried between depots would make any delay fatal. However, a strong wind behind them enabled them to set a sail on the sledge and maintain a good marching rate.
"We are so thin that our bones ache as we lie on the hard snow", wrote Shackleton. From 18 February onward they began to pick up familiar landmarks, and on the 23rd they reached Bluff Depot, which to their great relief had been copiously resupplied by Ernest Joyce. The range of delicacies over and above the crates of regular supplies was listed by Shackleton: "Carlsbad plums, eggs, cakes, plum pudding, gingerbread and crystallised fruit". Wild's laconic comment was "Good old Joyce".Their food worries were now resolved, but they still had to get back to Hut Point before the 1 March deadline. The final leg of their march was interrupted by a blizzard, which held them in camp for 24 hours. On 27 February, when they were still 33 nautical miles (61 km; 38 mi) from safety, Marshall collapsed. Shackleton then decided that he and Wild would make a dash for Hut Point in hopes of finding the ship and holding her until the other two could be rescued. They reached the hut late on 28 February. Hoping that the ship was nearby, they sought to attract its attention by setting fire to a small wooden hut used for magnetic observations. Shortly afterwards Nimrod, which had been anchored at the Glacier Tongue, came into view: "No happier sight ever met the eyes of man", wrote Wild later. It was a further three days before Adams and Marshall could be picked up from the Barrier, but by 4 March the whole southern party was aboard and Shackleton was able to order full steam towards the north. 
Question: What is the name of the person that "the worse he felt, the harder he pulled"?
Output (English): Shackleton.