 In 1870, a set of dies for the three-dollar piece was sent from the Bureau of the Mint's Engraving Department at the Philadelphia Mint to San Francisco.On May 14, 1870, Oscar Hugh La Grange, superintendent of the San Francisco Mint, sent a telegram to Mint Director Pollock, informing him that dies for the one- and three-dollar pieces had been received, but lacked the customary "S" mint mark, and asking for guidance.The dies were, per Pollock's instructions, returned to Philadelphia, but LaGrange informed Pollock that to secure a three-dollar piece to place in the cornerstone of the new San Francisco Mint building, Coiner J.B. Harmistead had engraved an "S" on the reverse die.