, 
WORK OF ‘‘ MAUD ’” EXPEDITION—SVERDRUP 933 
features can not be explained except by taking into account the 
rotation of the earth and the resistance which the tidal currents meet 
along the bottom and under the ice and also considering that the 
resistance affects the currents in great distances from the boundary 
surfaces on account of the eddy viscosity. The results of a theoreti- 
cal investigation of the influence of the rotation of the earth and the 
eddy viscosity on progressive waves were in good agreement with the 
observed tidal phenomena on the north Siberian shelf and may, 
perhaps, lead to a better understanding of corresponding phenomena 
on other continental shelves. 
As I have mentioned previously, we reached Bering Strait in 
August, 1925. At that time all of us were sailors. My duties were, 
for instance, to take care of the navigation of the ship and of the 
not less important cooking. Previously all of us had taken more 
or less part in the scientific work. Our cruise in the Arctic finally 
ended when the Maud was lying peacefully anchored off Nome 
three months ago. 
In conclusion, I hope that to-night I have been able to show you 
a phase of Arctic exploration which differs from the usual geo- 
graphical exploration, but is of no smaller importance. Our knowl- 
edge of the physics of the earth is incomplete so long as data from 
the Arctic and Antarctic regions are lacking. I hope that this ex- 
pedition, which went out through the energetic and _ persistent 
efforts of Capt. Roald Amundsen, may bring results which will fill 
a few gaps. However, we have traversed only a small region and 
have left many problems unsolved. The field for future explora- 
tion is tremendous. I hope that this, which I may call physical 
exploration of the Arctic, will continue for a long time after the 
completion of the map of the Arctic region and after the discovery 
of the last island. 
