"I found this in an inherited recipe box dated 1936. It originally called for 2 tablespoons fat, but I have substituted margarine or shortening with good results. I do not recommended making this recipe in a bread machine. If necessary, one tablespoon of active dry yeast can be substituted for the compressed yeast in this recipe."
In a small saucepan, cover peeled potatoes with water. Bring water to a boil and cook until tender, about 15 minutes. Drain and mash; let cool. In a separate sauce pan, stir the cornmeal into the 3 cups water. Bring to a boil and cook for 2 minutes. Stir in salt, sugar and shortening. Let cool to lukewarm.
In a large bowl, dissolve yeast in warm water. Add cooled cornmeal mixture and 2 cups of the cooled mashed potatoes. Stir in the rye flour and whole wheat flour 1 cup at a time; beating well after each addition. When the dough has pulled together, turn it out onto a lightly floured surface and knead until smooth and elastic, about 8 minutes. Lightly oil a large bowl, place the dough in the bowl and turn to coat with oil. Cover with a damp cloth and let rise in a warm place until doubled in volume, about 1 hour.
Deflate the dough and turn it out onto a lightly floured surface. Divide the dough into three equal pieces and form into loaves. Place the loaves into three lightly greased 9x5 inch loaf pans. Cover the loaves with a damp cloth and let rise until doubled in volume, about 40 minutes. Meanwhile, preheat oven to 375 degrees F (190 degrees C).
Bake in preheated oven for 60 to 70 minutes, until loaves sound hollow when tapped on the bottom.