Sept. 19, 1962 - A French cave explorer, still weakened by two months of underground isolation from which he was carried Monday, was able to speak today about his painful ordeal. The explorer, Michel Siffre, 23, who is confined to a hospital in Paris, said: “I would never be able to believe that my legs could be so weak.” He went into a cave in the French Alps on July 16, a bright summer’s day. The purpose was to test his reactions. For two months, he lived in near-freezing darkness relieved only by the pale light of several flashlights. He had no watch. One of the most interesting aspects of his experience, he said, is how completely he lost track of time. He believed that he had two or three weeks to go when he was told that his two months underground were over. “The humidity was 100%,” he said, “and the temperature was just above the freezing mark. My feet were in water all of the time. My clothes, the tent, my sleeping bag were always damp. At the beginning, I heated the tent. But each time I left the tent, the cold was so painful that I soon gave up the idea altogether.” Mr. Siffre said he had decided to undergo his experience after reading of experiments in isolation in air-raid shelters and in the training of astronauts.