PUMPING WATERS. 99 



circumstances will rarely demand this except in the 

 case of very heavy machinery. When excavating 

 to put in the concrete it may happen that a water 

 level is found, and in that case it is advisable to con- 

 tinue the cutting somewhat further down than re- 

 quired, and fill up to the water surface with broken 

 brick or stone well rammed. The actual composition 

 of the concrete is usually 6-1 Portland cement and 

 ballast, the latter being composed of 2-1 of i-J- in. 

 broken stone and sand. This is laid and rammed 

 in 4~in. layers till it is raised to within i in. of the 

 required height. It should then be covered with 

 damp sacks and left for 30 hours at least to set. 

 After this a rendering of i in. of sand and Portland 

 cement in equal quantities is applied, and the whole 

 brought to a hard, smooth surface and left for six or 

 eight days. It is customary for the contractor to 

 make a wooden template of the engine bed according 

 to the drawings supplied and with the exact position 

 of the foundation bolts marked on it. This is placed 

 in position, and the masonry, brickwork, or concrete 

 put in round it. The verticals are light trucks in 

 which the foundation bolts are eventually placed. 

 They have a shoe at the lower end, as shown in fig. 

 8 1, which is well embedded in the masonry or con- 

 crete. Gas pipe is frequently used in place of the wood 

 tubes. Foundation bolts should not be cemented on. 

 Regarding the actual erection and fitting up of 

 pumps, the suction pipe should always be full to the 

 sizes specified by the makers, and if very long, some- 

 what larger. It should have as few bends as possible 

 and these of a large sweep. The suction pipe if long 

 must always be laid with an uniform fall to avoid 



