<TABLE> <S> <C>

<ARTICLE> 5
<RESTATED>
<MULTIPLIER> 1,000
       
<S>                             <C>                     <C>                     <C>
<PERIOD-TYPE>                   3-MOS                   6-MOS                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1997             DEC-31-1997
<PERIOD-START>                             JAN-01-1997             JAN-01-1997             JAN-01-1997
<PERIOD-END>                               MAR-31-1997             JUN-30-1997             SEP-30-1997
<CASH>                                          46,940                  22,273                  13,094
<SECURITIES>                                         0                       0                       0
<RECEIVABLES>                                   39,030                  40,416                  40,861
<ALLOWANCES>                                        97                      97                      97
<INVENTORY>                                     33,593                  31,441                  33,863
<CURRENT-ASSETS>                               166,074                 137,345                 134,527
<PP&E>                                         251,229                 274,664                 296,408
<DEPRECIATION>                                 109,021                 113,573                 117,410
<TOTAL-ASSETS>                                 386,375                 379,839                 395,746
<CURRENT-LIABILITIES>                           37,482                  29,765                  38,285
<BONDS>                                            601                     541                     254
<PREFERRED-MANDATORY>                                0                       0                       0
<PREFERRED>                                          0                       0                       0
<COMMON>                                        20,472                  20,330                  20,316
<OTHER-SE>                                     289,339                 291,278                 294,913
<TOTAL-LIABILITY-AND-EQUITY>                   386,375                 379,839                 395,476
<SALES>                                         74,473                 146,491                 216,234
<TOTAL-REVENUES>                                     0                       0                       0
<CGS>                                           54,772                 107,948                 157,448
<TOTAL-COSTS>                                   54,772                 107,948                 157,448
<OTHER-EXPENSES>                                 1,336                   2,652                   3,980
<LOSS-PROVISION>                                    91                     308                     446
<INTEREST-EXPENSE>                                  54                     160                     222
<INCOME-PRETAX>                                 12,480                  21,771                  32,382
<INCOME-TAX>                                     4,930                   8,600                  12,790
<INCOME-CONTINUING>                              7,958                  15,337                  21,960
<DISCONTINUED>                                     161                     657                     834
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                                     8,119                  15,994                  22,794
<EPS-PRIMARY>                                     0.39                    0.78                    1.11
<EPS-DILUTED>                                     0.39                    0.76                    1.09
        

</TABLE>