chiefly between London and Sheffield. 



445 



111. 



115 



together; c c are the slates ; d d, the rafters; and e the gutter beam. The 

 fall found requisite to carry off the water is found to be from a half to three 



quarters of an inch in the yard, and this necessarily occasions the plane of the 

 roof to rise towards the centre of the building, as shown in the section 

 Jig. 117., in which the rise is indicated by the dotted lines f f f f. All the 

 care that this requires in slating or tiling is, to bring the upper edge of the 



