1858340

Information

• Patent Grant
• 1858340

• References
• Source

• Patent Number

  1,858,340

• Date Filed

  Not available

• Date Issued

  Tuesday, May 17, 1932
  92 years ago

• CPC

  • G01J1/14 - using comparison with a surface of graded brightness

• US Classifications

  • 356 - Optics: measuring and testing