According to the American Heritage Dictionary, since the Middle English period many writers have used "farther" and "further" interchangeably. However, there are cases where they are not interchangeable. "Further" can mean "additional" but "farther" cannot.
Here are further examples. *Here are farther examples.
Neither do I. The difference between the two words is that further can be used both in abstract and physical sense, while farther can not. Farther is used only in physical sense.cErtain collocations are only corect with further, but it is not true with farther. Further education.