The explorer Fridtjof Nansen explained this apparent fantasy of Pytheas as a mistake of Timaeus. Strabo and Diodorus Siculus never saw Pytheas' work, says Nansen, but they and others read of him in Timaeus. Pytheas reported only days' sail. Timaeus converted days to stadia at the rate of 1,000 per day, a standard figure of the times. However, Pytheas only sailed 560 stadia per day for a total of 23,800, which in Nansen's view is consistent with 700 stadia per degree. Nansen later states that Pytheas must have stopped to obtain astronomical data; presumably, the extra time was spent ashore. Using the stadia of Diodorus Siculus, one obtains 42.5 days for the time that would be spent in circumnavigating Britain. (It may have been a virtual circumnavigation; see under Thule below.)