Before revision: It took seven years to organize the first IPY which had twelve participating nations: the Austro-Hungarian Empire, Denmark, Finland, France, Germany, Netherlands, Norway, Russia, Sweden, United Kingdom , Canada , and United States.
After revision: It took seven years to organize the first IPY which had eleven participating nations: the Austro-Hungarian Empire, Denmark, Finland, France, Germany, Netherlands, Norway, Russia, Sweden, United Kingdom , and United States.