ANTOFAGASTA RAILWAY WATERWORKS. 



125 



of 10 feet and a height of 13 feet. It is set on a masonry 

 foundation 3 feet above the level of the pipe line and has an 

 inlet and an outlet in the base. It is fitted with an overflow 

 pipe and also has a float indicator, so that the inspectors may 

 note the amount of water in the tank. 



The following table is the standard form employed in the 

 department, giving the hydraulic data in connection with the 

 design of new pipe lines and has reference to the Siloli pipe 

 line construction in 1909/1910. The discharges are calculated 

 from Thrupps formula. 



Q = 



D--' 



■0209 /S 



where Q = Discharge in cubic feet per second. 

 S = Cosecant of slope. 

 D = Diameter oif pipe in feet. 



The designed capacity of the above main was 7,400 tons per 

 day, and tests since made of the delivery have given results about 

 5 per cent in excess of this figure. 



The No. 2 pipe line is laid with ordinary cast iron socket and 

 spigot pipes from San Pedro to Kilometre 110 of the railway. 

 The succeeding section from Kilometre 110 to Kilometre 59 

 was originally intended to be used as a high pressure main to 

 free water over the crest of an intei-vening ridge between Kilo- 

 metre 59 and Mejillones, and, as this would have necessitated 

 a maximum working pressure of 507 lbs. per square inch and a 

 maximum static head of 910 lbs. per square inch, exceptionally 

 heavy cast iron flange pipes were employed. The diameter of 

 the main is 10 inches and 9 inches and the 9-inch pipes are 1^2 

 inches thick. Under the maximum static head, the main has 

 withstood the high pressure without loss. In the laying of this 

 pipe line, the pipes were all 12 feet long, and in order to enable 



