Strong performance in its newspaper business helped Gannett Co. post a 17.5 percent increase in net income in its third quarter, ended Sept. 26.

Gannett earned $207.5 million in the quarter, compared with $176.5 million in the year-earlier period. Revenue increased by almost 11 percent, to $1.36 billion.

The Arlington media firm's earnings per share of 74 cents, a 19 percent increase, beat the 71 cents per share expectations of analysts surveyed by First Call Corp.

Gannett stock closed yesterday at $72.68 3/4, up 68 3/4 cents a share, on the New York Stock Exchange.

Sales of classified and national advertising coupled with declining newsprint costs led Gannett's newspaper division to report an operating income of $304.7 million, a 23 percent increase from the year-earlier quarter. Paid advertising pages at flagship USA Today jumped 16 percent, to 1,443. Ad revenue at the paper grew 16 percent.

For the first nine months of the year, Gannett's net income fell 11 percent, to $663 million, a decline attributed to extraordinary gains on the sale of assets in the first nine months of 1998. Excluding extraordinary items, the company's operating earnings rose 13 percent.

Gannett publishes 74 daily newspapers and operates 21 television stations and cable TV systems in three states.

Williams Industries Inc., a Falls Church heavy-construction company, reported that earnings jumped in its fourth quarter, ended July 31. The company profited from a boom in bridge and road building. Williams also booked a tax benefit carried forward from years when it lost money.

Profit in the quarter was $2.9 million (80 cents a share), up 54 percent from $1.88 million (53 cents) in the same quarter a year earlier. Revenue rose 14 percent, to $9.87 million from $8.64 million.

For the year, profit was $3.49 million (97 cents), up 88 percent from $1.85 million (52 cents). Revenue rose 15 percent, to $33.38 million from $28.9 million.

Results included a $1.9 million tax benefit carried over from the past, but even without that, the company pointed out, operating profit grew 42 percent in the year.

Williams Industries stock closed yesterday at $3.81 1/4, down 1.6 percent, or 6 1/4 cents a share, on the Nasdaq Stock Market.