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.
英
美
- 通過(guò)地下電纜傳輸的電話(huà)線(xiàn)路連接紐約和費城，全長(cháng)90英里?；紝ぞ€(xiàn)機的發(fā)明，導致自動(dòng)交換臺的成本大幅降低，并首次用于特拉華州的威明頓。
