Why does the ball drop on new year's eve?

I'm not sure why the ball dropping is the symbol for a new year. Is it just because its a Time Square tradition? Or does the ball symbolize anything? Does anybody know? I read that the New Year's eve ball dropping started in 1904.

Update: just found the official reason on wikipedia:

"The descent of a time ball each New Year’s Eve is a ritual derived from a common visual synchronization procedure once used primarily for navigation and astronomy. This practice evolved long before the age of electronic communications, but after mechanical timekeeping had reached a high degree of accuracy. In 1829 the first time ball was installed in England for visually synchronizing the chronometers used in navigation."