2307840

Information

• Patent Grant
• 2307840

• References
• Source

• Patent Number

  2,307,840

• Date Filed

  Not available

• Date Issued

  Tuesday, January 12, 1943
  81 years ago

• CPC

  • G09B9/32 - by projected image
  • G09B9/304 - by using a film

• US Classifications

  • 434 - Education and demonstration