\begin{table}%t6
%\centering
\par
\caption{\label{mass_nubi}Masses and surface densities of the clumps identified in the FCRAO $^{13}$CO(1--0) emission.} 
\smallskip 
\begin{tabular}{l r r r r r l r} 
\hline\hline  \noalign{\smallskip}
Clump &  $N_{^{13}{\rm CO}}$ & $M_{\rm LTE}$\tablefoottext{c}  & $\Sigma_{\rm LTE}$ & $n_{\rm LTE}$\tablefoottext{c} & $M_{\rm VIR}$\tablefoottext{c} & $\Sigma_{\rm VIR}$\tablefoottext{c}  & $n_{\rm VIR}$\tablefoottext{c} \\   
& ($\times$$ 10^{15}$~cm$^{-2}$) &  ($\times $$10^2~M_{\odot}$) & (g~cm$^{-2}$) & ($\times$$ 10^2$~cm$^{-3}$) & ($\times$$ 10^2~M_{\odot}$) &  (g~cm$^{-2}$) & ($\times$$ 10^2$~cm$^{-3}$)\\
(1)&(2)&(3)&(4)&(5)&(6)&(7)&(8)\\
\hline
co1              &  47.5   &  34.6  &  0.10      &    37.2    &  164.9 & 0.49   &    177.1        \\
co2              &  37.9   &  52.4  &  0.08      &    21.5     &  128.9 & 0.20   &    52.9           \\ 
co3              &  34.5   & 192.3  &  0.08      &    9.8      &  230.9 & 0.09   &    11.7          \\
co4\tablefootmark{a}     &   4.9   &  10.8  &  0.01      &    2.6      &  3.2   & 0.003  &    0.8           \\
co5\tablefootmark{b}     &  25.4   & 117.6  &  0.06      &    7.9     &  20.3  & 0.01   &    1.4           \\ 
co6              &  27.3   &  63.8  &  0.06      &    11.9     &  381.0 & 0.35   &    71.4           \\
co7              &  29.1   &  25.2  &  0.06      &    17.5    &  83.5  & 0.19   &    58.0          \\
co8             &  21.3   &  16.9  &  0.05      &    16.0      &  89.9  & 0.25   &    85.2          \\
co9             &  13.2   &  11.3  &  0.03      &    9.5     &  41.1  & 0.10   &    34.7           \\
co10 \tablefootmark{b}    &  22.0   &  94.9  &  0.04      &    5.9    &  342.7 & 0.15   &    21.4           \\ 
co11 \tablefootmark{b} &  20.8   & 144.3  &  0.04      &    4.4     &  251.6 & 0.07   &    7.7             \\
co12 \tablefootmark{b}    &  21.5   &  12.4  &  0.04      &    15.9     &  96.0  & 0.32   &    123.4          \\
co13              &  20.7   &  39.5  &  0.04      &    8.4      &  88.4  & 0.09   &    18.9          \\
co14 \tablefootmark{b}  &  33.6   &  38.0  &  0.06      &    15.9     &  71.6 & 0.11   &    30.0              \\ 
co15             &  12.3   &  19.9  &  0.02      &    5.5     &  27.6  & 0.03   &    7.5            \\
co16             &  11.6   &  47.7  &  0.02      &    2.9    &  22.4  & 0.01   &    1.4             \\
co17\tablefootmark{b}   &  19.7   &  32.6  &  0.04      &    7.7     &  59.5 & 0.06   &    14.0            \\
co18             &  15.7   &  31.5  &  0.03      &    5.6     &  117.2 & 0.11   &    20.8            \\
co19 \tablefootmark{a}    &   5.3   &   4.7  &  0.01      &    3.2    &  7.6   & 0.02   &    5.1            \\
\hline
\end{tabular}
\tablefoot{Column~(1): Clump; Cols.~(2)--(4): column density, LTE mass and surface density for $T_{\rm ex} = 20$~K; Col.~(5) Density from the LTE mass; Cols.~(6)--(7): virial mass and surface density; Col.~(8) Density from the virial mass. \tablefoottext{a}{The parameters are derived from a high velocity resolution resample (0.5~km~s$^{-1}$); } \tablefoottext{b}{the values are derived from the \mbox{BU-FCRAO GRS} data, because the clump is at the edge of our map; } \tablefoottext{c}{all the clumps are assumed to be at the far kinematic distances, except clump~co14 and clump~co17.}}
\end{table}