After the Civil War, Walker published a tunebook entitled "Christian Harmony" (1867), in which he adopted a seven-shape notation. He incorporated over half of the contents of "The Southern Harmony" into the "Christian Harmony", adding alto parts to those pieces which had lacked them. For the additional three shapes, Walker devised his own system - an inverted key-stone for "do", a quarter-moon for "re", and an isosceles triangle for "si" (or "ti"). Walker issued an expanded edition of "Christian Harmony" in 1873. In the same year, he published a collection of Sunday school songs entitled "Fruits and Flowers."