Shackleton's own account of the trip entitled, simply, 'South', also makes fascinating reading. One extraordinary thing I remember about the book is that despite all the tribulations, they managed to keep a record of exactly how many of each animal they slaughtered in order to stay alive! There's no mention of how they managed to keep a fire going throughout the trip - did they have matches in tins perhaps? They also ate a lot of 'pemmican' - presumably everyone knew what that was when the book was written. I had to look it up...