  The smallest polyatomic carbon chain, C$_{3}$, has been identified in
interstellar clouds (A$_{v}\sim$1 mag) towards $\zeta$ Ophiuchi, 20 Aquilae,
and $\zeta$ Persei by detection of the origin band in its
$A^{1}\Pi_{u}-X^{1}\Sigma^{+}_{g}$ electronic transition, near 4052\AA.
Individual rotational lines were resolved up to $J$=30 enabling the rotational
level column densities and temperature distributions to be determined. The
inferred limits for the total column densities ($\sim$1 to 2$\times10^{12}$
cm$^{-2}$) offer a strong incentive to laboratory and astrophysical searches
for the longer carbon chains. Concurrent searches for C$_2^{+}$, C$_2^{-}$ and
C$_3^{-}$ were negative but provide sensitive estimates for their maximum
column densities.
