ROMAN PAVEMENTS. 47 



The Material of the Tesserce. Sir Robert Edgcumbe reported 

 to Mr. Moule (Dorchester Antiquities, p. 15), on the authority of 

 an Italian workman, that the white tesserae were of a stone 

 called Min from a quarry near Verona. Another Italian work- 

 man told Mr. Moule himself that the stone is called Nim, and 

 comes, of course, from the neighbourhood of Nimes, in the south 

 of France. These two statements may be regarded as mutually 

 destructive ; they cancel out. We may be quite sure that all the 

 stones in our mosaics are of local origin. The last Italian 

 workman that was consulted went, indeed, so far as to admit to 

 Captain Acland that the white tesserae were of Dorset material, 

 but he declared that they had been burnt to make them white, 

 and that in his country they were called cogoli. This term is not 

 recognised by Italian dictionaries, but I have ascertained that it 

 is a dialect word meaning pebbles or cobbles, with which in the 

 north of Italy country streets and lanes are paved, and that the 

 man who lays them is called cugulu. No doubt cogoli is 

 descended from the Latin calculus, a pebble or gravel-stone, 

 and so, like many of our own dialect words, it has more nearly 

 retained its original form than the corresponding term used by 

 polite persons, which in this case is cioftolo, and the paved road 

 is ciottolato. 



I have had microsections made of one of each of the tesserae, 

 except the brick, and have presented duplicates to the museum. 

 And I am able to affirm that the white tesseras are of native, 

 unburnt, hard chalk. Chalk does not need to be burnt to make 

 it white, nor would burning harden it. The section shows the 

 delicate foraminiferae characteristic of that formation, as well as 

 a minute vein of calcite, certainly untouched by heat. It appears 

 that some of the Dorset chalk is so hard as to be classed by Mr. 

 Strahan (Survey of Weymouth, p. 236), among road metals. 

 Mr. Harrison (Geology of the Counties, p. 67), says that in 

 Devonshire the bottom layer of the lower white chalk is largely 

 quarried for building, and, though soft when extracted, it rapidly 

 hardens on exposure to the air. In the neighbourhood of 

 Cattistock, and even in Dorchester, many houses are built of 



