The heat moving to the other end is a technique used to heat treat
carbon tool steel tooling such as lathe tool bits. You heat the
working end to cherry red, then plunge the first inch into water, then
remove the piece. The heat from the opposite end that was not quenched
travels back into the quenched end to temper it. On larger pieces
these two steps must be done individually, but on small pieces the
remaining heat is enough to reach the 400 degrees needed for tempering.