January 4, 1985

December, with its long spells of springlike weather, was a cruel month for the ski areas of the Northeast. Yet those winter resorts that could offer their patrons season-defying alternatives, such as volleyball or sunbathing, report that they fared reasonably well. After having suffered through three poor seasons in the last four, ski operators had been hoping for a cold winter to bring a turn in their fortunes. But December's warmth has meant a bad start to this season, too.

The price of gold fell briefly below $300 an ounce in London trading yesterday, its first drop below that critical psychological level in a major market since June 1982, during the worldwide recession. Although the price later moved back above $300 in London and never fell below that in New York, analysts said they thought gold might drop as low as $260 an ounce in the near future. ''We're knocking on the door to a real breakthrough below 300,'' said Michael D. Kelley, vice president of the Prudential-Bache Metal Company, a dealer in precious metals. ''It seems to me that we'll have to see some selling,'' said Peter Feuerstein, an economist at the Chase Manhattan Bank who specializes in gold and foreign exchange. But, he said, ''I don't see a dramatic decline in the next six months, maybe to the low 290's.''

THOMAS EDISON brings electric lights to New York, looming like King Kong over miniature Manhattan buildings and streets. Benjamin Franklin flies a kite during a thunderstorm. A self-taught surgeon wields tiny scalpels and sponges in an operating room of grisly reality. This is the world of Theodora Skipitares: sculptor, set and costume designer, and now puppeteer. Sometimes her world brings to mind the cartoonlike art environments of Red Grooms or the eerily surreal waxworks of Madame Tussaud; at other times it resembles Japan's venerable Bunraku puppet performances or tabletop museum tableaux. Last night was the premiere of her complete ''Age of Invention,'' a 90-minute trilogy of plays about the American spirit of ingenuity. ''Age'' will run through Jan. 20 at the Theater for the New City on Second Avenue near 10th Street.

Investors who played it safe in 1984 by buying mutual funds that emphasized dividend and interest income and conservative stocks had good reason to celebrate on New Year's Eve. It was a year when the economy slowed down faster than the experts expected, and company earnings in general failed to meet analyst predictions. The funds that climbed the most were those that invested in bonds and the common stock of electric utilities, regional Bell Telephone operating companies and other businesses that benefited from a decline in interest rates. Topping the list of best-performing funds for the fourth quarter, or for the year as a whole, were the likes of The General Electric Long Term Interest Fund, Prudential-Bache Utilities Fund and Vanguard Qualified Dividend Portfolio 1.

''I condemn, in the strongest terms, those individuals who perpetrate these and all such violent, anarchist activities'' - President Reagan on bombings of abortion clinics. (A1:3.)