<ARTICLE> 5 <MULTIPLIER> 1,000 <PERIOD-TYPE> 6-MOS <FISCAL-YEAR-END> DEC-31-1998 <PERIOD-END> JUN-30-1998 <CASH> 78,000 <SECURITIES> 0 <RECEIVABLES> 4,138 <ALLOWANCES> 0 <INVENTORY> 0 <CURRENT-ASSETS> 82,808 <PP&E> 103,544 <DEPRECIATION> 68,670 <TOTAL-ASSETS> 225,242 <CURRENT-LIABILITIES> 10,410 <BONDS> 0 <PREFERRED-MANDATORY> 0 <PREFERRED> 575 <COMMON> 17,402 <OTHER-SE> 48,738 <TOTAL-LIABILITY-AND-EQUITY> 225,242 <SALES> 78,807 <TOTAL-REVENUES> 78,807 <CGS> 19,494 <TOTAL-COSTS> 31,540 <OTHER-EXPENSES> (1,133) <LOSS-PROVISION> 0 <INTEREST-EXPENSE> 95 <INCOME-PRETAX> 38,322 <INCOME-TAX> 0 <INCOME-CONTINUING> 38,322 <DISCONTINUED> 0 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> 38,322 <EPS-PRIMARY> 5.15 <EPS-DILUTED> 5.15