Money set aside by a municipality or corporation to _sink_ a debt at a
certain future time is called a SINKING FUND. For instance, if a city
should issue twenty-year bonds for $100,000 to secure money for street
improvements the entire debt would fall due in twenty years, but to
avoid having such a large amount fall due in one year, a proportional
sum is set aside each year as a sinking fund--that is, to _sink_, or
reduce, or wipe out the indebtedness when the bonds mature. Bonds are
not paid in advance of maturity.