The American house-carpenter; a treatise on the art of building, and the strength of materials (1867)
Hatfield, R. G. (Robert Griffith), 1815-1879 · New York, J. Wiley · leaf 30
Yet theyare useful when the operation is so large that a set-square cannotbe used. V d e^*v^^^^_^ r ■^f Fig. 29. 73.— To let fall a perpendicular. Let a, [Fig. 29,) be thepoint, above the line, h c, from which the perpendicular is re-quired to fall. Upon a, with any radius greater than a c?,… … Fig. 30. 74.— To erect a perpendicular at the end of a line. Let &,{Fig. 30,) at the end of the line, c a, be the point at which theperpendicular is to be erected. Take any point, as 6, above tlieline, c a, and with the radius, h a, describe the arc, d a e.through d and 6, draw the line, d e ;…
Carpentry · Architecture
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