| 摘要 |
A block 11, whose length is at least four times its width, and usable as a lintel, is of parallelopiped form, and has protrusions 23 on either its upper or lower face and recesses 19 on the opposite face, at least at the end regions of the block. These are for co-operation with complementary recesses or protrusions on building blocks 17, 22 in adjacent courses, which may be laid without the use of mortar. |
