Vintage The Martin Instrument Co. Elkhart Ind. Trombone 1914 SilverNotes In a Frank Holton & Co. Case Serial number is 10807. Dated using brasshistory. net. 1918 was the last year in union; highest marked serial was 18500. Based on other surviving Martin brass instruments the serial places it at 1914, 110 years old! Any reasonable offers will be considered. A Vintage The Martin Instrument Co. Elkhart Ind. Trombone 1914 Silver in Good condition! At Evolution Music, we attempt to highlight cosmetic defects (if any) by