V 
My last words of thanks are scarcely audible, but in them 
lies the key to the pulse beat of the book, — the thanks due my 
wife, who never failing, helped me with my work at home and 
abroad, on two journeys to Greenland, always self-sacrificing, 
devoting her art and the pure belief and joy of her spirit to the 
severe demands of my science. 
Birkerod, August 1923. 
W. T. 
