Source: Board of Governors of the Federal Reserve System (US)  

Release: H.4.1 Factors Affecting Reserve Balances  

Units:  Millions of U.S. Dollars, Not Seasonally Adjusted

Frequency:  Weekly, As of Wednesday

Notes:

The total face value of U.S. Treasury securities held by the Federal Reserve. This total is broken out in the lines below. Purchases or sales of U.S. Treasury securities by the Federal Reserve Bank of New York (FRBNY) are made in the secondary market, or with various foreign official and international organizations that maintain accounts at the Federal Reserve. FRBNY's purchases or sales in the secondary market are conducted only through primary dealers.

Bills: The current face value of the Federal Reserve's outright holdings of Treasury bills.
Notes and bonds, nominal: The current face value of the Federal Reserve's outright holdings of nominal Treasury notes and bonds.
Notes and bonds, inflation-indexed: The current face value of the Federal Reserve's outright holdings of inflation-indexed Treasury notes and bonds.
Inflation compensation: Inflation compensation reflects adjustments for the effects of inflation to the principal of inflation-indexed securities.

Source: Board of Governors of the Federal Reserve System (US)  

Release: H.4.1 Factors Affecting Reserve Balances  

Units:  Billions of U.S. Dollars, Not Seasonally Adjusted

Frequency:  Weekly, Ending Wednesday

Notes:

Currency in circulation includes paper currency and coin held both by the public and in the vaults of depository institutions. The total includes Treasury estimates of coins outstanding and Treasury paper currency outstanding. This definition of currency in circulation differs from the currency component of the money stock, a measure of currency used in some other Federal Reserve reports (for example, the H.6 release), which excludes currency held in vaults of depository institutions.

1984-1985 and Jan 11-Mar 15, 1989: Annual Statistical Digest 1984, 1985, 1989 Table 2.
Jan 8, 1986 to date except weeks ending Jan 11, 1989 - Mar 15, 1989: Federal Reserve Board H.4.1.