| 摘要 |
A trench is dug tor the foundation. One U-shaped form, open at the top, is placed in a portion of the trench. At a corner of the foundation, a pin is driven throug h the form into the ground until a protuberance on the pin contacts an upper edge of the form. A measuring rod is placed on the head of the pin and the elevation of an arbitrary mark on the rod is determined. At a second corner of the trench, at a lower elevation than the first corner, a second pin, identical to the first pin, is driven downward into a second U-shaped form until the elevation of the arbitrary mark of the rod when placed on the head of the latter pin is the same as the elevation of the arbitrary mark on the first pin. The second form is raised until its upper edge contacts the protuberance on the second pin. The second form is then secured so that its upper edge remains in contact with the protuberance on the second pin.
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