Julia Child, a native of California and a Smith College graduate; Simone Beck, French-born and -educated; and Louisette Bertholle, half French and half American, educated in both countries, represented an even blending of the two backgrounds and were singularly equipped to write about French cooking for Americans. Mrs. Child studied at Paris's famous "Cordon Bleu," and all three authors worked under various distinguished French chefs. In 1951 they started their own cooking school in Paris, "L'Ecole des Trois Gourmandes," at the same time that this book was taking shape. After that, Madame Beck