Telling Time without a Clock: Scandinavian Daymarks

"Very far north (or south) of the equator, however, the difference between the length of  daylight time in the summer is very much greater than in the winter. In parts of Scandinavia above the Arctic Circle (at a latitude of 66.5° North) the Sun does not set at all for part of the summer--it is daylight all the time. On the other hand, for part of the winter the Sun does not rise in these same areas. Obviously there is no point in dividing the daytime or nighttime into twelve sections if they are not taking place! Even if the Sun sets for only three of our modern hours in the summer, if one is dividing the daytime and nighttime into Babylonian/Egyptian-style "temporal hours", the nighttime hours will be so short compared to the daytime hours that there is hardly any point in making the divisions.

However, even very far north (or south), no matter where the Sun rises or sets, the middle of its path is above about the same part of the horizon. That means you can always tell when the middle of the day is if you know above which point on the horizon the highest point of the Sun's path is. Also, no matter how high the Sun is above the horizon, it always passes over the same points on the horizon after the same interval of time. Using these facts, the people living in Scandinavia developed a system of time-keeping quite different than the Babylonian/Egyptian system."

The full text of this highly detailed and informative article, courtesy of Harvard University, may be found here.