FLOATING. 



385 



arrangement will withstand a much greater pressure than will 

 vertical gratings. The inclination of the grating to the surface 

 of the water varies, depending on the absolute weight and 



Fi'_r. i'".7. Support of an oblique boom. 



stability of the rails which form the grating. Where these rails 

 are large in large booms they often attain lengths of 20 to 25 

 feet and a thickness below of 8 to 10 inches the inclination 



Ki-r. 2:>S. Oblique boom with masonry supports. 



of the grating may be 60 degrees, but otherwise it is placed 

 more obliquely, say, at an angle of 25 to 30 degrees. 



The rails of the grating are always round pieces, barked 

 spruce or larch, with their thicker ends in the water, and they 



F.U. c c 



