c.1910s Clarence A O’Brien Patent Attorney Washington DC Brass Letter Opener

This c.1910s brass advertising letter opener promotes Clarence A. O’Brien, a registered patent attorney located opposite the U.S. Patent Office in Washington, D.C. The reverse side provides detailed instructions for sending sketches or models for patent or trademark searches, reflecting early 20th-century patent procedures. Nicely engraved with geometric borders and a Capitol dome emblem, it represents an uncommon piece of professional advertising from the era.

– Material: Brass
– Size: 8¾” by 1⅛”
– Engraved both sides with patent instructions
– Period: c.1910s–1920s
– Origin: Washington, D.C.
– Type: Advertising letter opener

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