Reinforcement work to make the structures secure may be seen everywhere in the buildings (See fig 3-3 ~ 13). Much of this reinforcement work was done with steel plates, and cast iron pipes, but timber props of square or circular cross-section were more commonly used than anything else for this purpose. They vary remarkably little in size, as Table 3-3 shows. The reason for this may be that they used the same materials as were used in the industrial buildings. The number of such props and supports on each floor of the Nikkyu company flats is shown in Table 3-4.