VIA APPIA EOSE 361 



from poles (palangae) supported upon the shoulders of the porters 

 [32]. To move these stones into position they employed the crow- 

 bar (vectis). 



Rudus. — This second bed, shown on the key sketch at [12], was 

 made of broken stones smaller than those used in the statumen^ and 

 mixed with lime. Isidore, the Greek architect of the sixth century, 

 who completed the Church of Saint Sophia at Constantinople, called 

 material of this character imdus. When this layer consisted of 

 newly broken stone, it was called rvdus novv/rn, and to three parts of 

 stone there was added one part of quicldime. When reclaimed 

 aggregate {rudus redivlvmn) was used, mixed in the proportions of 

 two parts of lime to five parts of aggregate, this composition was 

 known as ruderatio. The beetle or rammer was used to consolidate, 

 level, and smooth the courses. Whether this layer was constructed 

 of new or old material, it was about 9 inches thick after compaction. 



The first step in laying this course consisted in spreading a layer of 

 mortar over the statutnen with a rake. Then the gravel or debris 

 was dumped upon the mortar and tamped into it with a beetle in such 

 a manner that the aggregate was left protruding. This rough sur- 

 face assured a substantial bond with the next layer {nucleus). When 

 aggregate for this type of work was hauled for a considerable dis- 

 tance, the 2-wheeled flaustvuTn was used. This vehicle had a basket 

 body, used for carrying heavy loads, and was generally drawn by 

 oxen as shown at [19]. 



Nucleus. — Into the roughened surface of the preceding course 

 (fmdus), there was bonded the third layer, commonly called the 

 nucleus^ or kernel [13], but sometimes referred to as the pudding or 

 pap. This layer of concrete consisted of small gravel, coarse sand, 

 and hot lime. This nucleus was placed in successive layers, each 

 compacted by a roller {cylindrus) [13-a]. At the side marglnes the 

 nucleus was about 1 foot thick and in the central agger the thickness 

 was increased to 1^^ feet in order to form the crown. Into this 

 freshly laid mortar was bedded the wearing surface, or sumtna crusta. 

 The nucleus formed the wearing surface for the side roads or mar- 

 gines, which were at a lower level than the central roadway or agger. 



Summa crusta or summum, dorsum. — This wearing course, called 

 the suTTtma crusta or swmmufni dorsum.^ illustrated at [14], was bedded 

 in the freshly laid iiucleus within the agger or central portion of the 

 roadway between the side curbs. The high crown, of about 6 inches 

 in the 16 Roman feet (15i/^ English feet), between the side curbs 

 {umbones), was designed to facilitate the passage of the projecting 

 hubs of chariots and for surface drainage. Side drains (cloacae), 

 an inlet of which is shown at [25-a] and an outlet at [25-b], were 

 built at regular intervals through the side curbs (umhones), and 

 under the margines, to the side ditches (fossae). 



