EXHIBIT (12) Computation of Ratios of Earnings to Fixed Charges and Earnings to Combined Fixed Charges and Preferred Stock Dividend Requirements Year ended December 31, 1997 1997 1996 1995 1994 1993 Income before provision for income taxes And fixed charges (Note A) $ 54,880,632 $ 49,713,981 $ 45,769,091 $ 44,293,156 $ 37,149,166 Fixed charges: Interest on first mortgage bonds $ 15,704,380 $ 14,014,643 $ 14,026,176 $ 12,190,405 $ 12,382,695 Amortization of debt discount and expense less premium 888,662 866,921 832,488 766,238 524,649 Interest on short-term debt 1,421,824 678,890 502,723 710,910 294,558 Other interest 58,072 276,880 280,497 239,916 215,708 Rental expense representative of an interest factor (Note B) 164,715 127,440 119,380 118,587 165,571 Total fixed charges $ 18,237,653 $ 15,964,774 $ 15,761,264 $ 14,026,056 $ 13,583,181 Preferred stock dividend requirements: Preferred stock dividend requirements not deductible for tax purposes $ 2,338,304 $ 2,338,304 $ 2,338,304 $ 1,484,992 $ 304,760 Ratio of income before provision for Income taxes to net income 1.540 1.531 1.516 1.538 1.479 Nondeductible dividend requirements 3,600,988 3,579,943 3,544,869 2,283,918 450,740 Deductible dividends 78,036 78,036 78,036 78,036 80,330 Total preferred stock Dividend requirements $ 3,679,024 $ 3,657,979 $ 3,622,905 $ 2,361,954 $ 531,070 Total combined fixed charges and preferred stock dividend requirements $ 21,916,677 $ 19,622,753 $ 19,384,169 $ 16,388,010 $ 14,114,251 Ratio of earnings to fixed charges 3.01 3.11 2.90 3.16 2.73 Ratio of earnings to combined fixed charges and preferred stock dividend requirements 2.50 2.53 2.36 2.70 2.63 <footnote> NOTE A: For the purpose of determining earnings in the calculation of the ratio, net income has been increased by the provision for income taxes, non-operating income taxes and by the sum of fixed charges as shown above. NOTE B: One-third of rental expense (which approximates the interest factor).