The New Metal Worker Pattern Book —— A Complete Course of Instruction in the Modern Methods of Developing, and Cutting the Patterns for Sheet Metal Work, Giving the Principles Under-Lying Practically Every Problem That Is Likely to Come Up in Practice and Explaining the Selection and Use Of

----- 新金属工人模式书

ISBN: 9781332168842 出版年：2016 页码：476 Geo W Kittredge Forgotten Books

Arch-es are usually semicircular (fig. Semi elliptical, segmental, pointed (fig. 7 7 )'or M'oresque (horse shoe) (fig. 7 in shape, according to the style of archi tecture with which they are used. The top of an opening may be perfectly level and yet composed of wedge shaped blocks So combined as to be self -supporting, in which case it is called a flat arch. (fig. 7 9)