FLUMES AND THEIR STRUCTURE. 



137 



a means of fastening the flume to the bracket. Fig. 36 

 shows a larger flume half -circular in se<5lion, supported 

 by a bracket at each side resting on horizontal timber. 

 In both these cases the board beneath the flume may 

 be omitted, but it aids in eredlion, and adds stability 

 to the strudlure. The smaller sizes do not have riveted 

 connedlions between joints, and therefore, especially in 



FIG. 37— CROSS-SECTION OF LARGE IRON FLUME. 



the use of the single post support, may be easily moved 

 from one locality to another. 



The general shape of the flumes in section is para- 

 bolic. Where depth is restridfed and the volume of 

 water to be carried is large, the type shown in Fig. 

 37 is adopted, the sides being parabolic and the bottom 

 circular. In this case the bottom of the flume is sup- 

 ported throughout its entire length by plank or timber 

 on edge let down into the sill of the trestle to conform 

 to the shape of the flume. 



In case it is desired iron may be substituted for the 

 timber supports. Figs. 38 and 39 show how admi- 



