APPENDIX B. 323 



the exposed edges of the beds and vertical joints. The beds shall be cut entirely 

 through and be parallel, and vertical joints shall be full for not less than 12 inches from 

 the face, and for as much more as the stone will allow. Pointed-face stone shall be 

 laid with -inch joints, except where it joins special or coping stone, when it shall 

 have chiseled drafts and f-inch joints at the abutting surfaces. It shall be furnished 

 as headers and stretchers in the proportion of one header to two stretchers, and no 

 stone shall be less than 4 feet in length or 2 feet in breadth, except by special permission. 

 Stretchers must have one-third more bed than rise. 



(h) Rock-face Stone. Rock-face stone shall have the exposed faces accurately 

 determined by pitch-lines around the edges of the beds and vertical joints, and there 

 shall be no projections greater than 4 inches beyond these lines. The cutting and the 

 dimensions of the joints, the sizes and the proportion of headers and stretchers, and 

 the requirements for laying next to special or coping stones, shall be the same as for 

 " Pointed-face Stone." 



(*') Backing. Backing shall be of well-shaped stones, of not less than 6 square feet 

 of area on the smallest bed, with the sides hammered or picked off so that the vertical 

 joints between backing stones will not exceed an average of 4 inches. Beds shall be 

 full and approximately parallel, so that the bed-joints shall average i inch in thickness 

 for three-quarters of the area of the stone. No part of the stone shall be higher than 

 the face stone, and no through vertical joint will be allowed with face and backing 

 stone, but special care must be taken to prevent the passage of water. 



(/) Courses. The number and arrangement of the courses shall be as shown on the 

 drawings, and no variation therefrom will be allowed without special permission. 



(k) Position of the Various Classes of Stone.* The foundation masonry, where 

 exposed to the action of water, down stream from the upper hollow quoin, shall be 

 faced with rock-face stone unless otherwise directed, and except where special stones 

 are required. This shall include the lower miter-wall, the lower coffer-wall, the cham- 

 ber faces of the main wall to the level of the top of the lower miter-sill (except in the 

 gate recesses where it shall be one course lower), and the down-stream face of the upper 

 miter-wall. Up stream from the upper hollow quoin the foundation masonry shall 

 be of backing, except where special stones are required, and shall include the upper 

 miter-wall, the upper coffer-wall, and the chamber faces of the main walls to the level 

 of the top of the upper miter-sill, except in the gate recesses, where it shall be one 

 course lower. The lower ends of both main walls, to a height of 2 feet below the lower 

 pool level, and the outside of the river-wall to the same height, and the upper ends of 

 both main walls to a height of 2 feet below the upper pool level, shall be of backing. 



The inside faces of the main walls above the foundation masonry shall generally 

 be of pointed-face stone. 



*This description is for a lock with a fixed dam and a high upper miter-wall. In a lock with a 

 movable dam the miter-walls are usually near the same level, and the outside of the river-wall requires 

 pointed or smooth-face work, and a vertical face where the dam abuts against it. 



