Combine sweet potatoes and raisins (or cranberries -- add as many as you like). Sprinkle with lemon juice. Mix lightly and set aside.
Combine flour, 1 c sugar, baking powder, salt, baking soda, and mace (or nutmeg). Sift together into a large bowl.
Cut shortening (or butter) into dry ingredients with a pastry blender (or two butter knives) until pea-sized bits form.
Beat egg in a small bowl. Add orange juice and water. Fold liquid into dry ingredients by hand until flour is just moistened. Fold in sweet potato mixture.
Place batter in a greased 9x5 loaf pan. Combine 1 tb sugar and cinnamon; sprinkle on top.
Bake at 350F for 50 minutes or until an inserted toothpick comes out clean. Remove from pan and cool on rack.
NOTES: This recipe takes a small sweet potato or half of a large one. The original called for two 9x5 loaf pans and baking for 40 minutes, but I like the bigger single loaf. The substitutions in parentheses are also my changes from the original.