Dominion Federal Savings & Loan Association in McLean said yesterday that its earnings dropped 56 percent in its second quarter because of rising interest rates.

William L. Walde, chairman of the institution, said that rising interest rates during the quarter dampened desire for residential loans. He said this "contributed to lower loan fee income and a reduction of loan sales in the secondary market."

Dominion Federal said it earned $1.9 million (37 cents a share), down from $4.3 million (85 cents) in the same period a year ago. For the six months ended Sept. 30, earnings were $4.8 million (94 cents), down 48 percent from $9.3 million ($1.84).

Dominion Federal said it had not adjusted its financial statements to account for the $129 million judgment against it last summer in a lawsuit filed by Penthouse International Ltd. It is appealing the decision in the case, in which Penthouse alleged that the S&L reneged on financing an Atlantic City casino project.

Columbia First Federal Savings and Loan Association of Washington reported earnings of $1.7 million (53 cents) in its fourth quarter, a 46 percent drop from $3.1 million ($1.22) in the same period last year. For its fiscal year, which ended Sept. 30, earnings fell 8 percent, to $7.6 million ($2.33) from $8.2 million ($2.88).

The S&L said one reason for the decrease the was a net increase of $1.7 million in income tax expenses.

Star Technologies Inc. of Sterling, a supplier of scientific computers, reported earnings of $597,000 (4 cents per share) in its second quarter, down 15.3 percent from $705,000 (5 cents) in the same period a year ago. Revenue for the quarter, which ended Sept. 30, fell 23 percent, to $9.1 million from $11.8 million.

The company attributed the decline in revenue to "delays in receipt of certain orders" and to a decline in shipments of one of its computers to a General Electric Co. division. Star said the lower revenue was partially offset by increased sales to the seismic exploration market.

For the six months, Star reported a 58 percent increase in profit, to $1.3 million (9 cents) from $824,000 (6 cents). Revenue fell 10 percent, to $18.1 million from $20.1 million.

Legg Mason Inc., a Baltimore brokerage, said it earned $3 million (35 cents) in its second quarter, up 36 percent from $2.2 million (32 cents) a year ago. Revenue increased to $56.2 million from $31.9 million. The company said the increases were in part the result of several recent acquisitions.

For the first six months of the year, Legg Mason earned $5.4 million (63 cents), up 10 percent from $5 million (72 cents) a year ago. The per-share figures were skewed by an increase in the number of shares outstanding this year. Revenue rose 64 percent, to $108.6 million from $66.3 million.