You dig a square in the steep base of the mountain, and set up two uprights and top them with two joists. 马克·吐温.傻子出国记.
The hammer-block, _a_, weighing four tons, is guided in its ascent and fall by grooves in two massive uprights, which hold the whole together. 弗雷德里克·科利尔·贝克维尔.伟大的事实.