In large mixing bowl, dissolve yeast in lukewarm water. Set aside. In a small bowl, combine cool water, salt, sugar and butter; add to yeast mixture. Stir in high-gluten flour and enough bread flour to make a soft dough. Turn onto floured board and knead until smooth and elastic, about 2 minutes. Place in greased bowl and cover; let rise in cool place until doubled, about 2 hours. Divide dough into 3 equal parts. Roll each piece on lightly floured board into a 14 x 8-inch rectangle. Roll the long side of the rectangle toward you in a tight roll. Pull into shape, about 1 1/2-inches in diameter. Grease cookie sheets and sprinkle them lightly with cornmeal. Place the 3 loaves seam side down onto cookie sheets. Cover and let rise until doubled, about 1 1/2 hours. Brush with cold water. Cut 3 or 4 shallow diagonal slashes across each loaf. Set a shallow pan of water in the bottom of the oven. Bake at 400°F for 40 minutes or until done, brushing loaves with cold water 2 or 3 times during baking. Cool on wire rack.