Most of the major problems of Arctic geography have been solved, and there are now few stretches of coastline which have not been at least roughly mapped. In the Antarctic there are still huge blank spaces on the map, but even there the kind of rough and ready maps that were made by early explorers would now be scarcely adequate. A modern polar survey must be much more accurate and comprehensive if it is to be worth while and have any permanent value, and it therefore takes up rather more of the time which used to be almost entirely devoted to travel. On the other hand, modern inventions such as the light but accurate eyepiece reading theodolite, the camera, and the aeroplane, have made available very much more rapid methods of survey than were possible even twenty years ago.