The Treasurer of the US, not the Sec of Treasury.
Individual mints had complained about having to fill orders for single coins from individuals and the time it took to send replies, wait for payment, then mail the coins via registered, etc. The problem became worse when new silver designs were introduced in 1892 and then even worse with Lincoln cents, Buffalo nickels, etc. The Philadelphia Mint had staff to handle medal and proof coin orders, but not circulated coins for individuals. The other mints had no facilities, so the work had to take time from other duties of clerks. The eventual solution was for the Treasurer of the US to be sent a supply of coins from each mint, and then fill orders. The Treasurer had staff to handle cash and operating the Cash Room at Main Treasury in Washington. (The Treasurers had already been quietly giving out gold $1 and $3 to VIPs visitors and members of Congress....See RAC 1909-1915 for details...These were used by wives, daughters and girlfriends for jewelry.)