United States. (San Francisco - Via Panama). 1851. Folded letter addressed to Amsterdam, Holland, written from 'Gildemeester de Fremery & Co, San Francisco' (with oval firms cachet on face in blue), dated '3rd Dec 1851', endorsed 'per "Golden Gate" via New York & Liverpool', rated '6' in manuscript with New York transit 'Jan 6 (1852)' in red with oval 'FORWARDED BY HERCKENRATH & VAN DAMME/ N. YORK' on reverse in green, London transit '19 Jan 52' with manuscript '1/4' (U,K, debit to Holland), with small Dutch entry cachet 'Engeland/ over Ostende' in red on reverse (Van der Linden 1024), charged '110' in manuscript Dutch cents due rating and Amsterdam arrival '21/1' in red on reverse.
Letter docked at San Francisco, was then sent via Panama undercover to New York with forwarding agent 'Herckenrath Van Damme, New York' applied.
Mailed by the 'Pacific Mail Steamship Company "Golden Gate" to Panama. Then Trans-Isthmus mails, freight and passengers went by Panama railroad to Aspinwall and then by steamer via Key West to New York.
The forwarding agent Herckenrath struck their identifying backstamp and deposited this letter in the mails to UK unpaid.