1400552

Information

• Patent Grant
• 1400552

• References
• Source

• Patent Number

  1,400,552

• Date Filed

  Not available

• Date Issued

  Tuesday, December 20, 1921
  103 years ago

• CPC

  • G01J3/461 - with colour spinners
  • G01J3/52 - using colour charts

• US Classifications

  • 434 - Education and demonstration