248 ROMAN PAVEMENTS. 



squared blocks of chalk, and, though some of them are more 

 than 200 years old, the face of the chalk is little the worse. 

 They are shown in this photograph, and here is a lump of hard 

 chalk that has been used as a door stopper, and has been kicked 

 about every day and all day on a floor of Portland Cement for 

 seven years, and it has proved for itself that it would make 

 durable cubes for any mosaic. The yellow tesserae are of 

 ordinary oolite, the egg-structure coming out well, under the 

 microscope. The blue-grey is a stratified limestone, and answers 

 to like- coloured bands of Lower Purbeck ; indeed, Mr. Osmond 

 Fisher believes he can see in it traces of cyprides, the character- 

 istic fresh-water fossil. And the black is a non-fossiliferous 

 marble stained by ferruginous percolation. Its affinity is to the 

 limestones of Devonshire. 



The Fret. This term is from the old French /mV, trellis- work, 

 and denotes a pattern composed of continuous combinations of 

 straight lines. When they interlace they form a rectilinear 

 intreccio. 



The Meander fret. The meander in its origin was, of course, 

 a curvilinear decoration, but in wood-carving, taking lines of 

 least resistance, it passed by degrees into a fret, into a running 

 rectilinear device. All zigzags that do not cross each other are 

 meanders, even those complicated zigzags called key-patterns. 

 In the example before us it surmounts the cruciform floriated 

 centre, and is so arranged as to produce an emissive or radiant 

 effect. 



Interlaced Designs. The chief intrecci of this Mosaic are the 

 Cable, the Braid which is of three strands, and the Guilloche. 

 As regards the two former, the points of their intersections are 

 made more evident to the eye by means of light-coloured 

 centerings, but they are, none the less braids and cables. 



The term Guilloche has been variously defined. Some say 

 that it is any twisted ornament which repeats itself by its 

 returning strands ; and others call it the tool by which such an 

 ornament can be made, because the French verb guillocher is 

 "to engine-turn/' and is derived from the man's name who 



