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\citet{Myers1996} and \citet{Williams1999} present a model of infall that predicts line profiles similar to these observations. They assume two clouds (near and far) falling toward a common center and estimate the resulting line profiles accounting for optical depth effects as well as standard radial-dependencies of velocity and excitation temperature. \citet{Myers1996} show that an optically thick line and a higher excitation temperature on the cloud on the fars side can produce a blue-shifted weighted line-shape. With further simplifications they show that by measuring five parameters, the Myers et al. (1996) model allows an estimate of the infall velocity. The measured parameters are: $\sigma$ (velocity dispersion of an optically thin tracer), T$_{BD}$ (the blue-shifted excess emission), T$_{RD}$ (the red-shifted emission), T$_D$ (the plateau emission), v$_{red}$ (the red-shifted peak emission velocity) and v$_{blue}$ (the blue-shifted peak emission velocity). See Figure 2 in \citet{Myers1996} for a diagram of these different quantities. When all quantities can be measured, the infall velocity is estimated to be:  \begin{equation} \begin{equation*}  v_{in} \approx \frac{\sigma^2}{v_{red} - v_{blue}} \ln\left( \frac{1+e T_{BD}/T_D}{1+e T_{RD}/T_D}\right)  \end{equation} \end{equation*}  When the optical depth and V$_{in}$/$\sigma$ are sufficient large, the red peak can disappear (see Myers et al. 1996 for discussion of this effect). Thus, we are limited in our numerical analysis to N117-3. We estimated the relevant line parameters by eye. Our line profile measurements and infall velocity calculation are given in Table \ref{infalltable}. Since we do not have an optically thin measurement of this source, we have assumed the value of the velocity dispersion based on the optically thin $^{34}$CS observations by \citet{Williams1999}. They found a typical value to be 1.5 km/s. A smaller value would decrease the infall velocity (see equation above).