A text book of geometrical drawing, for the use of mechanics and schools, in which the definitions and rules of geometry are familiarly explained (1849)
SPAN of an arch is the distance between the points ofsupport; which is generally the width of the opening to be cov-ered; as A. B. These points are called the springing points; themass against which the arch rests is called the abutmejst. 3rd. The risE; height or versed siive of an arch; is the… … \ J-: ]• G Fig. J. Fig. 4. K
