The 31c/240 Herschel-pair climber (or 31c/240 reaction) is the mechanism defining the speed of the 31c/240 orthogonalengineered spaceships, namely centipede, shield bug and silverfish. It consists of a pair of Herschels climbing two parallel chains of blocks. Certain spacings between the block chains allow gliders from each Herschel to delete the extra ash objects produced by the other Herschel. Two more gliders escape, one to each side, leaving only an exact copy of the original block chains, but shifted forward by 9 cells. The mechanism was first discovered by Dave Greene on April 19, 2013.[1]
