103. Rubble Arches

Rubble Arches. For rough purposes, arches are sometimes built of rubble, as shown in Fig. 58, in which b represents the wall carried by the rubble arch, the ring stones of which, as a, should be narrow and roughly dressed to a wedge shape. Such arches should always be laid in cement mortar, as they depend considerably upon the adhesive power of the mortar for their stability.

103 Rubble Arches 185

Fig. 58.