# Page:Great Neapolitan Earthquake of 1857.djvu/166

These figures apply to wall apertures of the usual moderate size of windows and doors. When very much larger and wider, and covered at top with plate-band arches or stone lintels, two or more fissures ${\displaystyle \mathrm {F} }$ often take place, by the opposite movements of the first and second semivibration of the wave, and large fragments fall out.