As soon as Plateau found himself fairly out of the physicians' hands, with restored health, he resumed his experiments with ardor. He was most happy in finding co-laborers who gave him the most efficient and willing help. "Thanks to their generous co-operation," said he, "the career of scientific work remains open to me. I can, in spite of the infirmity with which I have been visited, put in order the materials which I have amassed, and even undertake new researches."
When this experimental work began again, Plateau showed at once that the clouding of his physical sight had only served to clarify his mental vision. At first he could not give up his independence, and for some time he wrote between metallic slips; his assistants soon learned to decipher the writing. Later, however, he gave up this habit, and contented himself with writing to dictation.
His temper was usually calm and equable; he never uttered a complaint on account of the many deprivations which his blindness imposed. He was bright and amusing in his conversation, and yet he was, as all thinkers are, in the main, sober.
His memory, which was naturally a good one, had become phenomenal by cultivation. It was only necessary to hear an ordinary poem read once or twice for him to be able to repeat it accurately. This gift was one of his greatest compensations for the loss of sight, and of incalculable benefit in his experiments made by the hands of others. His method, given by his son-in-law and biographer, G. van der Mensbrugghe, is as follows: In a day devoted to experiment, speaking of the latter years of the physicist's life, he says: "The old man's face is animated; he announces with admirable precision all the precautions to be taken that the apparatus should work. According to his often expressed desire, the assistant acquaints him successively with his operations, even to the smallest point. No manœuvre is left to his personal valuation. The apparatus is at last ready to be set in motion. The master, who imagines and regulates all the dispositions, makes still other suggestions; he assures himself by different means that all is ready in accordance with his will. At last the assistant is asked to operate—the experiment succeeds! What a satisfaction, what a relief for the noble worker who has conceived it! For greater assurance he causes it to be repeated, with various modifications suggested by the descriptions of the observed effects. If all passes as he has foreseen, he at once asks his secretary to write to his dictation all the details of the experiment. No point is forgotten, for the provisional wording ought to represent, as exactly as possible, all that had been verified. But if the observation did not meet his expectations, in spite of the precautions he had deemed necessary, the physicist promised
