J. Carter Brown, the lean, aristocratic director of the National Gallery of Art, a man as comfortable in a tux as in a jogging suit, went up to Capitol Hill the other day to tell Congress why he needs $34,915,000 of your money and mine to keep the joint operating next year. For the most part, these hearings are love-feasts. The subcommittee chairman, Rep. Sidney Yates (D-Ill.), is a champion of federal spending for the arts. Brown seemed surprised, therefore, when Yates was less than satisfied with Brown's explanation of how the NGA's conservation department preserves the museum's 2,466 paintings and thousands of other artworks. "I'm still not clear, and I'm pressing you, and you're resisting," said Yates, with an edge to his voice. A budget book that Brown submitted showed the conservators did major restoration last year on 44 paintings, five textiles, 125 works of art on paper, 83 sculptures and decorative objects and nine frames, plus minor work on hundreds of other objects. Of a thousand paintings on view, Brown said, "Over half could well use conservation help." He said he needs twice the nine-member conservation staff to take care of a "tremendous backlog," adding that the museum's objects have suffered from "benign neglect," and the conservation department's expensive lab equipment is "sitting there unused because we don't have technicians." This wasn't enough for Yates. "Are any of your paintings in jeopardy?" he demanded. "Deterioration is going on," Brown answered, "but it is critical in only a certain number of cases . . ." Yates shook his head: "I'm still not clear on what your conservators are doing." In the end, the matter remained unclear to Yates, with Brown promising to present a more comprehensive report on the matter next year. It was clear, however, that whenever you ask Uncle to cough up megabucks, you've got to expect to take a little heat along with the warmth.