1220920

Information

• Patent Grant
• 1220920

• References
• Source

• Patent Number

  1,220,920

• Date Filed

  Not available

• Date Issued

  Tuesday, March 27, 1917
  107 years ago

• CPC

  • H04L15/285 - Telegraph sounders; Apparatus for acoustic reception

• US Classifications

  • 178 - Telegraphy
  • 340 - Communications: electrical