3 i8 THE IMPROVF.MEXT OF RIVERS. 



| inch in diameter, and where two or more are used in the same post they must not be 

 further apart than 7 feet vertically. They shall K- provided with sleeves about 2 feet 

 from each end, so that these ends can be withdrawn when the concrete is finished. Bolts 

 built into the wall for the purpose of holding any portion of the forms shall be not less 

 than I inch in diameter, and these and the ends of the tie-rods must be greased before 

 being built in. No iron or wire used in fastening the forms and left imbedded in the 

 concrete must come within 4 inches of the face. 



Facing templates shall be of dressed plank 8 inches wide, 2 inches thick on the 

 top edge, and i inch thick on the bottom edge, and shall be provided with rings or 

 staples for lifting. They must be lifted up carefully, and without wrenching or prying, 

 so as not to disturb the adjoining faeing, and must be kept in good working condition. 



Forms shall remain in position for at least three days after the concrete has been 

 completed in them; and must remain longer in cold weather. They shall be removed 

 by the contractor at his own expense, and such materials in them as may be satisfactory 

 to the Engineer may be used in the construction of other forms after proper cleaning 

 and trimming. 



All material used for the construction of forms must be supplied and placed by 

 the contractor at his own expense, and be included in his price for concrete. 



37. Voids and Openings. All necessary voids and openings for conduits or wells, 

 or for such other purposes as may be required by the Engineer, shall be left in the con- 

 crete. Recesses for ladders, coffer-beams, etc., shall be formed by wooden boxes of 

 the required shape, dressed t<> leave a smooth surface on the finished work. 



38. Mixing and Placing. The concrete is to be mixed by machinery except when 

 the quantity required is very small, when it may be mixed by hand. The gravel or 

 broken stone shall be thoroughly drenched just before being put in the mixer, and the 

 order of placing in the mixer shall be as directed by the Engineer. The water used 

 in the concrete must be clean, and the proportion regulated as directed, so as to 

 produce a concrete which will quake after being rammed. All mixing must be thor- 

 oughly done and must be satisfactory to the Engineer, and shall be continued until 

 every particle is covered with mortar; the mass shall then IK- kept in motion so that 

 its initial set will not occur before it is in its place of deposit. All mortar, in concrete 

 or elsewhere, must be used before the cement has begun to set, otherwise the mortar 

 must be wasted and the cement will be charged against the contractor as damaged 

 cement. No re-tempering will be allowed under any circumstances. If the water to 

 be used is taken from the river, the contractor must provide settling tanks to the satis- 

 faction of the Engineer, to be used whenever the river water is too muddy to be fit ( 

 in his judgment, for mixing mortar or concrete. 



Before beginning any foundation section of concrete, the bed-rock shall be thor- 

 oughly cleaned, the rock being roughened, if so directed by the Engineer, as described 

 in paragraph 30, and a grout of neat cement shall be spread thereon and thoroughly 

 brushed in, to provide a tight joint between the foundation and the wall. 



