<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM CONDENSED
CONSOLIDATED BALANCE SHEETS AND STATEMENTS OF EARNINGS AND IS QUALIFIED IN ITS
ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
       
                             
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-END>                               JUN-30-1998
<CASH>                                           1,079
<SECURITIES>                                    22,765
<RECEIVABLES>                                   67,745
<ALLOWANCES>                                       993
<INVENTORY>                                     17,539
<CURRENT-ASSETS>                               113,403
<PP&E>                                         485,242
<DEPRECIATION>                                 210,249
<TOTAL-ASSETS>                                 460,726
<CURRENT-LIABILITIES>                           77,302
<BONDS>                                        169,718
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                         3,091
<OTHER-SE>                                     152,971
<TOTAL-LIABILITY-AND-EQUITY>                   460,726
<SALES>                                         33,712
<TOTAL-REVENUES>                               167,632
<CGS>                                           24,938
<TOTAL-COSTS>                                  108,675
<OTHER-EXPENSES>                                36,924
<LOSS-PROVISION>                                    47
<INTEREST-EXPENSE>                               5,999
<INCOME-PRETAX>                                 18,806
<INCOME-TAX>                                     7,091
<INCOME-CONTINUING>                             11,715
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                    11,715
<EPS-PRIMARY>                                      .52
<EPS-DILUTED>                                      .51