Conversation by underground cable, 90 miles-New York to Philadelphia. Invention of Keith Line Switch, resulting in enormous reduction in cost of automatic boards. First used at Wilmington, Delaware.

• 通过地下电缆传输的电话线路连接纽约和费城，全长90英里。基思寻线机的发明，导致自动交换台的成本大幅降低，并首次用于特拉华州的威明顿。