228 TOWERS AND TANKS FOR WATER-WORKS. 



hardly be employed, owing to its cost, upon any portion of a 

 foundation for a stand-pipe except possibly the first course 

 immediately below the superstructure, where such course is 

 exposed. Frequently the cut stone is used only as a belt 

 upon the outer perimeter of the foundations, the interior or 

 core being "backed up" with rough rubble masonry, well 

 flushed and levelled with cement. This last type of masonry 

 consists of rubble proper and range rubble masonry; the 

 former being stone of almost any dimension, roughly sledged 

 for use, and bedded in cement without regard to horizontal 

 jointing; range rubble requires that the stone shall be laid to 

 a rough line horizontally; the first of these distinctions of 

 rubble masonry is generally used below the ground-line and 

 for the core of the foundations, while the range rubble is em- 

 ployed for the exposed surfaces up to the first course under 

 the structure, which is frequently of ashlar finish. As with 

 the quarrying, the local conditions modify the cost of all 

 masonry work, but roughly the following will give an idea of 

 the relative value of several masonry classifications: 



First-class ashlar $12.00 to $15.00 C. Y. 



Coursed rubble 4.00" 6.00 " 



Rough rubble 3.00" 5.00 " 



Concrete I part Port, cement, 2 sand, 



4 broken stone 4.00 " 6.00 " 



Ordinary brick masonry cement 



mortar 5.00" 8.00 " 



In stone masonry, Rankine's general rule, modified to 

 suit particular conditions and individual ideas, is largely used 

 and is as follows : ^ 



RANKINE'S RULE. 



I. Build the masonry as far as possible in a series of 

 courses, perpendicular, or as nearly so as possible, to the 



