APPENDIX B. 



(o) Cement and Sand. (See preceding clauses for Concrete.*) 



(p) Mortar. Mortar of natural cement shall be composed of two parts of sand to 

 one part of loose cement ; mortar of Portland cement shall be composed of three parts 

 of sand to one part of loose cement, unless otherwise specified. No mortar of natural 

 cement shall be used within 2 feet of the outside of the wall, except below the level of 

 the lower miter-sill. All mortar must be mixed thoroughly and in small batches, and 

 used before it has begun to set, and the mortar-beds must be kept covered when so 

 directed by the Engineer. 



(q) Pointing. All exterior joints shall be scraped out as soon as filled, and shall be 

 subsequently properly cleaned, wetted, and pointed, to a depth of not less than i inch 

 with Portland cement mortar, composed of one part of cement to one part of sand, 

 thoroughly hammered and finished with proper tools. Before the final acceptance 

 of the work all such joints which have not been satisfactorily pointed shall be scraped 

 out to a depth not less than i inch, and shall be repointed to the satisfaction of the 

 Engineer without cost to the United States. 



(r) Sills, Anchorage of. The miter-sills and coffer-sills at the upper and lower ends 

 of the lock are to be anchored to the masonry by bolts, as shown. The bolts shall be 

 furnished and set by the contractor. The stones under the sills through which the 

 anchor-bolts pass must be selected, cut, and set with a view to drilling for the bolts. 

 Holes for the bolts must be carefully drilled in such a manner as not to jar or disturb 

 the masonry through which they pass. 



(j) Pivot-stones. The four pivot stones, are to be selected stones, carefully cut and 

 set according to directions given. The cast-iron pintle-plates shall be furnished by 

 the contractor, and placed in mortar of neat Portland cement. The cost of cutting 

 for and setting these plates will be covered by the price for "Special Stones," which 

 will be the classification of these stones, as hereinbefore stated. 



(f) Gate Anchorages. The stones under the line of the gate anchorages, through 

 which the anchor-bolts pass, must be selected, cut, and set with a view to drilling for 



the bolts, and extend to a depth of feet below the top of the coping. They shall 



be laid in Portland cement mortar, and have no joints in the backing on the vertical 

 line of the bolts. Holes for the bolts must be drilled in such a manner as not to jar or 

 disturb the masonry through which they pass. 



(u) Frost. Masonry shall not be laid when the temperature is below 30 degrees 

 Fahrenheit, except by special permission, nor when, in the judgment of the Engineer, 

 it is likely to be injured by frost. All new or unfinished work must be protected from 

 frost by the contractor at his own expense, and any work injured by lack of proper 

 protection must be removed and replaced by him without cost to the United States. 



* It will generally be found preferable to use a Portland cement throughout, although a good Eastern 

 natural cement will give satisfactory results for the foundation and interior of the wall. The saving in 

 cost, however, is small, especially as a richer mortar must be used with the latter kind. 



