Chequer-brick for vertical cowpers and cowper chequerwork constructed from these chequer-bricks

摘要

A chequer-brick (20) of cruciform shape is provided for the chequerwork of vertical cowpers. The brick (20) comprises two cross-beams (11, 12) of different breath and the same length with four recesses (13, 14, 15, 16) arranged in the points of the cross respectively and a further centrally located recess (17). The bricks (20) are laid one on top of the other so that the recesses and the intersections between the cross-beams form vertical conduits.