WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE BALANCE
SHEETS AT DECEMBER 31, 1998 AND THE STATEMENTS OF OPERATIONS FOR THE TWELVE
MONTHS ENDED DECEMBER 31, 1998 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO
SUCH FINANCIAL STATEMENTS INCLUDED AS PART OF ITS ANNUAL REPORT ON FORM 10-K FOR
THE PERIOD DECEMBER 31, 1998.
</LEGEND>
       
<S>                             <C>
<PERIOD-TYPE>                   12-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-START>                             JAN-01-1998
<PERIOD-END>                               DEC-31-1998
<CASH>                                       6,212,541
<SECURITIES>                                         0
<RECEIVABLES>                                2,267,032
<ALLOWANCES>                                         0
<INVENTORY>                                          0
<CURRENT-ASSETS>                             8,479,573
<PP&E>                                     123,593,353
<DEPRECIATION>                              27,539,807
<TOTAL-ASSETS>                             104,568,280
<CURRENT-LIABILITIES>                                0
<BONDS>                                              0
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                             0
<OTHER-SE>                                 104,568,280
<TOTAL-LIABILITY-AND-EQUITY>               104,568,280
<SALES>                                              0
<TOTAL-REVENUES>                            12,551,660
<CGS>                                                0
<TOTAL-COSTS>                                7,513,712
<OTHER-EXPENSES>                                     0
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                                   0
<INCOME-PRETAX>                                      0
<INCOME-TAX>                                         0
<INCOME-CONTINUING>                                  0
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                 5,470,220
<EPS-PRIMARY>                                        0
<EPS-DILUTED>                                        0
        
[ARTICLE] 5
[LEGEND]
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE BALANCE
SHEET AT SEPTEMBER 30, 1998 (UNAUDITED) AND THE STATEMENT OF OPERATIONS FOR THE
QUARTERLY PERIOD ENDED SEPTEMBER 30, 1998 (UNAUDITED) AND IS QUALIFIED IN ITS
ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS INCLUDED AS PART OF ITS
QUARTERLY REPORT ON FORM 10-Q FOR THE PERIOD SEPTEMBER 30, 1998.
[/LEGEND]
       
<S>                             <C>
[PERIOD-TYPE]                   9-MOS
[FISCAL-YEAR-END]                          DEC-31-1998
[PERIOD-START]                             JAN-01-1998
[PERIOD-END]                               SEP-30-1998
[CASH]                                       5,897,422
[SECURITIES]                                         0
[RECEIVABLES]                                2,638,095
[ALLOWANCES]                                         0
[INVENTORY]                                          0
[CURRENT-ASSETS]                             8,535,517
[PP&E]                                     123,749,970
[DEPRECIATION]                              25,769,570
[TOTAL-ASSETS]                             106,567,800
[CURRENT-LIABILITIES]                                0
[BONDS]                                              0
[PREFERRED-MANDATORY]                                0
[PREFERRED]                                          0
[COMMON]                                             0
[OTHER-SE]                                 106,567,800
[TOTAL-LIABILITY-AND-EQUITY]               106,567,800
[SALES]                                              0
[TOTAL-REVENUES]                             9,665,063
[CGS]                                                0
[TOTAL-COSTS]                                5,615,602
[OTHER-EXPENSES]                                     0
[LOSS-PROVISION]                                     0
[INTEREST-EXPENSE]                                   0
[INCOME-PRETAX]                                      0
[INCOME-TAX]                                         0
[INCOME-CONTINUING]                                  0
[DISCONTINUED]                                       0
[EXTRAORDINARY]                                      0
[CHANGES]                                            0
[NET-INCOME]                                 4,364,453
[EPS-PRIMARY]                                        0
[EPS-DILUTED]                                        0
        
[ARTICLE] 5
[LEGEND]
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE BALANCE
SHEET AT JUNE 30, 1998 (UNAUDITED) AND THE STATEMENT OF OPERATIONS FOR THE
QUARTERLY PERIOD ENDED JUNE 30, 1998 (UNAUDITED) AND IS QUALIFIED IN ITS
ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS INCLUDED AS PART OF ITS
QUARTERLY REPORT ON FORM 10-Q FOR THE PERIOD JUNE 30, 1998.
[/LEGEND]
       
<S>                             <C>
[PERIOD-TYPE]                   6-MOS
[FISCAL-YEAR-END]                          DEC-31-1998
[PERIOD-START]                             JAN-01-1998
[PERIOD-END]                               JUN-30-1998
[CASH]                                       5,782,869
[SECURITIES]                                         0
[RECEIVABLES]                                2,687,411
[ALLOWANCES]                                         0
[INVENTORY]                                          0
[CURRENT-ASSETS]                             8,470,280
[PP&E]                                     123,894,498
[DEPRECIATION]                              23,994,294
[TOTAL-ASSETS]                             108,439,090
[CURRENT-LIABILITIES]                                0
[BONDS]                                              0
[PREFERRED-MANDATORY]                                0
[PREFERRED]                                          0
[COMMON]                                             0
[OTHER-SE]                                 108,439,090
[TOTAL-LIABILITY-AND-EQUITY]               108,439,090
[SALES]                                              0
[TOTAL-REVENUES]                             6,660,401
[CGS]                                                0
[TOTAL-COSTS]                                3,738,695
[OTHER-EXPENSES]                                     0
[LOSS-PROVISION]                                     0
[INTEREST-EXPENSE]                                   0
[INCOME-PRETAX]                                      0
[INCOME-TAX]                                         0
[INCOME-CONTINUING]                                  0
[DISCONTINUED]                                       0
[EXTRAORDINARY]                                      0
[CHANGES]                                            0
[NET-INCOME]                                 3,130,456
[EPS-PRIMARY]                                        0
[EPS-DILUTED]                                        0
        
[ARTICLE] 5
[LEGEND]
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE BALANCE
SHEET AT MARCH 31, 1998 (UNAUDITED) AND THE STATEMENT OF OPERATIONS FOR THE
QUARTERLY PERIOD ENDED MARCH 31, 1998 (UNAUDITED) AND IS QUALIFIED IN ITS
ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS INCLUDED AS PART OF ITS
QUARTERLY REPORT ON FORM 10-Q FOR THE PERIOD MARCH 31, 1998.
[/LEGEND]
       
<S>                             <C>
[PERIOD-TYPE]                   3-MOS
[FISCAL-YEAR-END]                          DEC-31-1998
[PERIOD-START]                             JAN-01-1998
[PERIOD-END]                               MAR-31-1998
[CASH]                                       5,181,198
[SECURITIES]                                         0
[RECEIVABLES]                                2,897,705
[ALLOWANCES]                                         0
[INVENTORY]                                          0
[CURRENT-ASSETS]                             8,078,903
[PP&E]                                     123,987,058
[DEPRECIATION]                              22,207,546
[TOTAL-ASSETS]                             109,943,743
[CURRENT-LIABILITIES]                                0
[BONDS]                                              0
[PREFERRED-MANDATORY]                                0
[PREFERRED]                                          0
[COMMON]                                             0
[OTHER-SE]                                 109,943,743
[TOTAL-LIABILITY-AND-EQUITY]               109,943,743
[SALES]                                              0
[TOTAL-REVENUES]                             3,306,704
[CGS]                                                0
[TOTAL-COSTS]                                1,871,684
[OTHER-EXPENSES]                                     0
[LOSS-PROVISION]                                     0
[INTEREST-EXPENSE]                                   0
[INCOME-PRETAX]                                      0
[INCOME-TAX]                                         0
[INCOME-CONTINUING]                                  0
[DISCONTINUED]                                       0
[EXTRAORDINARY]                                      0
[CHANGES]                                            0
[NET-INCOME]                                 1,529,822
[EPS-PRIMARY]                                        0
[EPS-DILUTED]                                        0
        
[ARTICLE] 5
[LEGEND]
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE BALANCE
SHEETS AT DECEMBER 31, 1997 AND THE STATEMENTS OF OPERATIONS FOR THE TWELVE
MONTHS ENDED DECEMBER 31, 1997 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO
SUCH FINANCIAL STATEMENTS INCLUDED AS PART OF ITS ANNUAL REPORT ON FORM 10-K FOR
THE PERIOD ENDED DECEMBER 31, 1997.
[/LEGEND]
       
<S>                             <C>
[PERIOD-TYPE]                   12-MOS
[FISCAL-YEAR-END]                          DEC-31-1997
[PERIOD-START]                             JAN-01-1997
[PERIOD-END]                               DEC-31-1997
[CASH]                                       4,789,501
[SECURITIES]                                         0
[RECEIVABLES]                                2,909,486
[ALLOWANCES]                                         0
[INVENTORY]                                          0
[CURRENT-ASSETS]                             7,698,987
[PP&E]                                     124,148,108
[DEPRECIATION]                              20,429,936
[TOTAL-ASSETS]                             111,519,209
[CURRENT-LIABILITIES]                                0
[BONDS]                                              0
[PREFERRED-MANDATORY]                                0
[PREFERRED]                                          0
[COMMON]                                             0
[OTHER-SE]                                 111,519,209
[TOTAL-LIABILITY-AND-EQUITY]               111,519,209
[SALES]                                              0
[TOTAL-REVENUES]                            13,784,688
[CGS]                                                0
[TOTAL-COSTS]                                7,512,287
[OTHER-EXPENSES]                                     0
[LOSS-PROVISION]                                     0
[INTEREST-EXPENSE]                                   0
[INCOME-PRETAX]                                      0
[INCOME-TAX]                                         0
[INCOME-CONTINUING]                                  0
[DISCONTINUED]                                       0
[EXTRAORDINARY]                                      0
[CHANGES]                                            0
[NET-INCOME]                                 6,578,035
[EPS-PRIMARY]                                        0
[EPS-DILUTED]                                        0
        
[ARTICLE] 5
[LEGEND]
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE BALANCE
SHEET AT MARCH 31, 1997, JUNE 30, 1997 AND SEPTEMBER 30, 1997 (UNAUDITED) AND
THE STATEMENTS OF OPERATIONS FOR THE QUARTERLY PERIOD ENDED MARCH 31, 1997, JUNE
30, 1997 AND SEPTEMBER 30, 1997 (UNAUDITED) AND IS QUALIFIED IN ITS ENTIRETY BY
REFERENCE TO SUCH FINANCIAL STATEMENTS INCLUDED AS PART OF ITS QUARTERLY REPORT
ON FORM 10-Q FOR THE RESPECTIVE PERIODS THEN ENDED.
[/LEGEND]
       
<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]                                       3,756,930               3,700,981               3,965,649
[SECURITIES]                                         0                       0                       0
[RECEIVABLES]                                2,718,929               2,768,091               3,127,523
[ALLOWANCES]                                         0                       0                       0
[INVENTORY]                                          0                       0                       0
[CURRENT-ASSETS]                             6,475,859               6,469,172               7,093,172
[PP&E]                                     124,283,349             124,153,386             124,252,743
[DEPRECIATION]                              15,060,037              16,852,011              18,640,518
[TOTAL-ASSETS]                             117,387,823             115,310,206             114,096,263
[CURRENT-LIABILITIES]                                0                       0                       0
[BONDS]                                              0                       0                       0
[PREFERRED-MANDATORY]                                0                       0                       0
[PREFERRED]                                          0                       0                       0
[COMMON]                                             0                       0                       0
[OTHER-SE]                                 117,387,823             115,310,206             114,096,263
[TOTAL-LIABILITY-AND-EQUITY]               117,387,823             115,310,206             114,096,263
[SALES]                                              0                       0                       0
[TOTAL-REVENUES]                             3,141,734               6,381,050              10,163,705
[CGS]                                                0                       0                       0
[TOTAL-COSTS]                                1,985,768               4,005,652               6,003,098
[OTHER-EXPENSES]                                     0                       0                       0
[LOSS-PROVISION]                                     0                       0                       0
[INTEREST-EXPENSE]                                   0                       0                       0
[INCOME-PRETAX]                                      0                       0                       0
[INCOME-TAX]                                         0                       0                       0
[INCOME-CONTINUING]                                  0                       0                       0
[DISCONTINUED]                                       0                       0                       0
[EXTRAORDINARY]                                      0                       0                       0
[CHANGES]                                            0                       0                       0
[NET-INCOME]                                 1,242,623               2,489,858               4,381,203
[EPS-PRIMARY]                                        0                       0                       0
[EPS-DILUTED]                                        0                       0                       0
        
[ARTICLE] 5
[LEGEND]
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE BALANCE
SHEETS AT DECEMBER 31, 1996 AND THE STATEMENTS OF OPERATIONS FOR THE TWELVE
MONTHS ENDED DECEMBER 31, 1996 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO
SUCH FINANCIAL STATEMENTS INCLUDED AS PART OF ITS ANNUAL REPORT ON FORM 10-K FOR
THE PERIOD DECEMBER 31, 1996.
[/LEGEND]
       
<S>                             <C>
[PERIOD-TYPE]                   12-MOS
[FISCAL-YEAR-END]                          DEC-31-1996
[PERIOD-START]                             JAN-01-1996
[PERIOD-END]                               DEC-31-1996
[CASH]                                       5,508,568
[SECURITIES]                                         0
[RECEIVABLES]                                2,835,397
[ALLOWANCES]                                         0
[INVENTORY]                                          0
[CURRENT-ASSETS]                             8,343,965
[PP&E]                                     123,720,710
[DEPRECIATION]                              13,265,647
[TOTAL-ASSETS]                             120,636,573
[CURRENT-LIABILITIES]                          664,650
[BONDS]                                              0
[PREFERRED-MANDATORY]                                0
[PREFERRED]                                          0
[COMMON]                                             0
[OTHER-SE]                                 119,971,923
[TOTAL-LIABILITY-AND-EQUITY]               120,636,573
[SALES]                                              0
[TOTAL-REVENUES]                            14,160,889
[CGS]                                                0
[TOTAL-COSTS]                                7,694,463
[OTHER-EXPENSES]                                     0
[LOSS-PROVISION]                                     0
[INTEREST-EXPENSE]                                   0
[INCOME-PRETAX]                                      0
[INCOME-TAX]                                         0
[INCOME-CONTINUING]                                  0
[DISCONTINUED]                                       0
[EXTRAORDINARY]                                      0
[CHANGES]                                            0
[NET-INCOME]                                 7,262,658
[EPS-PRIMARY]                                        0
[EPS-DILUTED]                                        0
        
[ARTICLE] 5
[LEGEND]
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE BALANCE
SHEET AT MARCH 31, 1996, JUNE 30, 1996 AND SEPTEMBER 30, 1996 (UNAUDITED) AND
THE STATEMENT OF OPERATIONS FOR THE QUARTERLY PERIOD ENDED MARCH 31, 1996,
JUNE 30, 1996 AND SEPTEMBER 30, 1996 (UNAUDITED) AND IS QUALIFIED IN ITS
ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS INCLUDED AS PART OF ITS
QUARTERLY REPORT ON FORM 10-Q FOR THE RESPECTIVE PERIODS THEN ENDED.
[/LEGEND]
       
<S>                             <C>                     <C>                     <C>
[PERIOD-TYPE]                   3-MOS                   6-MOS                   9-MOS
[FISCAL-YEAR-END]                          DEC-31-1996             DEC-31-1996             DEC-31-1996
[PERIOD-START]                             JAN-01-1996             JAN-01-1996             JAN-01-1996
[PERIOD-END]                               MAR-31-1996             JUN-30-1996             SEP-30-1996
[CASH]                                      16,602,892               8,324,605               6,086,305
[SECURITIES]                                         0                       0                       0
[RECEIVABLES]                                2,221,462               2,562,497               2,467,010
[ALLOWANCES]                                         0                       0                       0
[INVENTORY]                                          0                       0                       0
[CURRENT-ASSETS]                            18,824,354              10,887,102               8,553,315
[PP&E]                                     117,353,650             122,976,730             123,802,605
[DEPRECIATION]                               7,940,989               9,689,891              11,472,195
[TOTAL-ASSETS]                             130,521,544             126,309,271             122,870,163
[CURRENT-LIABILITIES]                        3,970,365               2,095,107               1,040,550
[BONDS]                                              0                       0                       0
[PREFERRED-MANDATORY]                                0                       0                       0
[PREFERRED]                                          0                       0                       0
[COMMON]                                             0                       0                       0
[OTHER-SE]                                 126,551,179             124,214,164             121,829,613
[TOTAL-LIABILITY-AND-EQUITY]               130,521,544             126,309,271             122,870,163
[SALES]                                              0                       0                       0
[TOTAL-REVENUES]                                     0               6,701,290              10,177,679
[CGS]                                                0                       0                       0
[TOTAL-COSTS]                                1,768,039               3,720,689               5,706,737
[OTHER-EXPENSES]                                     0                       0                       0
[LOSS-PROVISION]                                     0                       0                       0
[INTEREST-EXPENSE]                                   0                       0                       0
[INCOME-PRETAX]                                      0                       0                       0
[INCOME-TAX]                                         0                       0                       0
[INCOME-CONTINUING]                                  0                       0                       0
[DISCONTINUED]                                       0                       0                       0
[EXTRAORDINARY]                                      0                       0                       0
[CHANGES]                                            0                       0                       0
[NET-INCOME]                                 1,734,431               3,537,797               5,168,162
[EPS-PRIMARY]                                        0                       0                       0
[EPS-DILUTED]                                        0                       0                       0
        

</TABLE>