\magnification=\magstep2

$$
\sigma_T =  {  {{8 \pi}\over{3}} { \left( {{e^2}\over{m_e c^2}} \right)}^2 }
         = { 6.65 \times 10^{-25} {\rm \ cm^2} }
$$

$$
\kappa_{\lambda}  = \kappa_{\lambda,bb} + \kappa_{\lambda,bf} + 
                        \kappa_{\lambda,ff} + \kappa_{es} 
$$

$$
\overline{\kappa}  = \overline{\kappa_{bb} + \kappa_{bf} + 
                        \kappa_{ff} + \kappa_{es} }
$$
\bye

