Prince Rupert's cube significant person Jean Henri van Swinden
6
        
      
      −
      
        
          2
        
      
      ≈
      1.03527
    
    {\sqrt {6}}-{\sqrt {2}}\approx 1.03527
  ,slightly larger than one, is capable of passing through the hole.Approximately 100 years later, Dutch mathematician Pieter Nieuwland found that a better solution may be achieved by using a hole with a different angle than the space diagonal. In fact, Nieuwland's solution is optimal. Nieuwland died in 1794, a year after taking a position as a professor at the University of Leiden, and his solution was published posthumously in 1816 by Nieuwland's mentor, Jean Henri van Swinden.Since then, the problem has been repeated in many books on recreational mathematics, in some cases with Wallis' suboptimal solution instead of the optimal solution.