Corrections to serious errors--second printing.

Corrections are listed by the name of the dvi and prt files, which is
based on the page number(s) affected.


pg348 Serious errors were corrected in the only equation on this page.
      Because of another correction, the page is found with the seventh
      printing.

pg521 Paragraph in middle of page was wrong.  New one completely
      replaces it. Equation numbers changed to avoid a gap.