Schaff, Philip. "Immersion and Pouring in History." The Oldest Church Manual Called the Teaching of the Twelve Apostles. Second Edition, Revised and Enlarged. New York: Funk & Wagnalls, 1886, 41-57.
Having reviewed some images of baptism from the Roman catacombs, Schaff considers the historic patterns of immersion and pouring as they pertain to the Didache. The rule at the time seems to be triple immersion, while the exception is pouring (Schaff 1886, 42). Schaff is clear that the authorities he brings us in his discussion are all Paedo-Baptist. He then cites numerous authorities who all agree that the triple immersion is the normal way of baptism, and that pouring would be used only in exceptional circumstances, such as when there is a lack of water.
The habit of pouring developed largely after the 13th century (Schaff 1886, 44). Schaff finds the change to be made only in the Church of the West (Schaff 1886, 51). While we might assume that pouring would be preferred in cold climates, this was not the case. Immersion remained the custom in England through at least the sixteenth century. It was after the time of the Reformation that sprinkling and pouring became more widespread (Schaff 1886, 52). Schaff also observes that the distinction was not due to a conservative Reformation reaction against Anabaptists. The Anabaptists didn't insist on immersion until the 17th century. Schaff summarizes the positions taken, concluding that the arguments of paedobaptists for pouring are generally inconsistent (Schaff 1886, 55). Modern (to Schaff and to me) Protestant Baptists also have inconsistent practices, such as their insistence on immersion or no baptism at all, or their practice of immersing only once (Schaff 1886, 56).