| 摘要 |
<p>A pattern for defining the profile of an arch is produced from a unitary block of material or materials having the required structural strength to support the arch materials during construction and sufficient ductility or resilience at its surface to accommodate irregularities present in the arch materials. The pattern may be produced from a single block of polystyrene material whose upper profile corresponds to the desired underside of an arch to be constructed using the pattern and whose undersurface is generally flat.</p> |
