The weather outside was drizzly and damp but inside an air of anticipation pervaded the National Bureau of Standards (NBS) in Gaithersburg Sunday as 264 hopeful junior and senior high school students displayed their projects in the 26th Annual Montgomery Area Science Fair.

Stephanie Ann Telesetsky, a 16-year-old senior at Stone Ridge School in Bethesda, and Jaya Yodh, 16, a junior at Springbrook High School in Silver Spring, were the top winners in the senior division, in which 57 students from 10th through 12th grades competed. Both girls will receive all-expenses paid trips to Houston in May to compete with 450 other students from across the United States in the International Science and Engineering Fair.

Winners in the junior division were Frank Li, 13, of Ridgeview Junior High in Gaithersburg, and Wendy Wright, 14, who attends Takoma Park Junior High.

Several awards were given in each of 12 categories in both the senior and junior divisions. In all, 139 students won a first-, second-, third-place or honorable mention award in their category. In addition, 32 science associations and corporations gave awards at the fair, which is sponsored by NBS, a bureau in the Commerce Department.

Telesetsky won on the basis of her work on the cell mechanism that resists certain antibiotics in several strains of E. coli, a bacterium that lives in the human gut. The project earned her a $500 award earlier this month as one of 40 finalists in the prestigious Westinghouse Science Talent Search.

Yodh received the other grand-prize award for her study: "The Interaction of Agar with Hemoglobin." She was trying to use agar, an extract of red algae, as a carrier for hemoglobin, which could help in the treatment of sickle-cell anemia and other blood disorders.

"I've always been interested in science," said Yodh. "I want to help people . . . maybe in medical research."

Alternate winner in the senior division was Nancy Freed for her project entitled "Acid From the Sky," a study of acid rain in Maryland. Freed, a junior at Paint Branch High School in Burtonsville, began working on her project last August. She also took first place in the environmental sciences category and received five association awards.

In the junior division, Li and Wright each won a $50 U.S. Savings Bond in the competition against 207 other students from grades seven through nine.

Li, who also won first prize in his category, environmental science, studied the effects of pesticides on earthworms. "My heart just stopped beating," he said of hearing his name announced as a winner. The youth, who said he works "better under pressure," was still putting on the finishing touches the night before the fair began.

Wright, who studied the efficiency of electricity-generating windmills, won first place in the junior division engineering category and seven other awards from associations--picking up the most honors at the fair. "I put a lot of work into it," she said.

Other entrants did not leave empty-handed. Steven Markowitz, a senior at Montgomery Blair High School in Silver Spring, won first place in the senior division engineering category and three other association awards for his creation, named Titan I Robot. "When it's working, it can do virtually anything . . . vacuum, dust," Markowitz boasted earlier. Unfortunately, the three-foot-high, rudimentary R2D2, made of mail-order parts, part of a water cooler and household items, suffered a minor tragedy. "Yesterday, one of the power wires broke loose and burned out the circuitry," explained Markowitz, who has been studying electronics since he was 8 years old.

Jorge Plinio Montalvan, an eighth grader at Our Lady of Mercy Junior High in Potomac, won third place in the junior division environmental science category and an award from the National Energy Foundation. Montalvan, 13, explainedhow his project, a search for an energy source besides coal that could produce synthetic natural gas, proved that wood also can be used to produce synthetic natural gas.

Thirteen-year-old Arvind Sinha, who attends Thomas Pyle Junior High in Bethesda, won five prizes at the fair, including first place in the junior division engineering category, for creating an electric turnstile that can be used to keep track of people in a hallway. Sinha recently completed a computer design course at the University of Maryland and plans to take more in the near future.

"It is the biggest fair (in this area) since the '50s," when the public interest in science reached a peak, noted John Pancella, the director and secondary science coordinator of Montgomery County public schools. "The number of entrants has increased for the ninth straight year," he said, "a 14 percent increase over last year."

People say interest in the sciences has declined over the years in the United States, Pancella said, but "we make a mockery of that. . . . The whole community is an exception. We have better media coverage, a higher level of interest and more acute levels of awareness." Children today "know the future needs" and are "encouraged through their school and parents."

"It's great," said 13-year-old Tracy Lutz, who attends Ridgeview Junior High and won two awards for her project entitled "Voyager: Rendezvous and Discovery." "All the kids understand each other."