What does the International Date Line do?
This long line on maps and g1obes zigzags down the middle of the wide Pacific Ocean. It is the International Date Line, and it is not marked on the watery face of the Sea. It is merely part of the man made system of lines of latitude and longitude. Its purpose is to mark the dawning of each new calendar day. The international date line is based on the lines of longitude that girdle the Earth from pole to pole. You may wonder what lines of latitude or longitude have to do with the date and why the line that marks the international date for all the world should zig and zag down the center of the lonely Pacific Ocean. These puzzling questions, however, have very sensible answers. The man made system of latitudes and longitudes mark off the face of the globe somewhat like the streets that nark off the blocks of a city. When you know the streets and cross streets you can find the intersection you want, and from there it is no problem to reach the building you want. Lonely oceans and uninhab
