FiG. 12 



rinishcd v.-ooden pond sluice bein^ installed in a brook 

 obstructinc pond. 



The corapletion of the pond construction lacks only the installation of the outlet 

 arrangement, the sluice. The sluice (lUg. 10) is conpletely built before it is installed. 

 It consists of a horizontal tube of rectangular cross section, v/hich must be as long as 

 the ^Tidth of the dani bottom, and of a vertical shank of at least 30 cm. v.idth, v^;.ich is 

 open in front (see Fig. 12). Tlie little sluice boards are shoved dovm the vertical shank 

 betv/een tv:o grooves (see Figs. 10 and 12). It is best to make the sluice froai knot-free 

 pine T,'-od having a tl.ickness of about 4 to 5 cm., as shov.'n in i'ig, 10, 



In the place v.-here the sluice is to be installed in the dan, the ground is to be 

 leveled, prepared, and fiml;^ conpacted (see Figs. 11 and 12). By means of the horizontal 

 sharic, the sluice is set up sli;;htly inclined so that the vertical slianl; stands free in the 

 pond at the gro-jid line of the dam (not in the dam). Two sraall cror.s laths are placed 

 under the bottom board (Fig. 10), so that later no vater runs under the sluice. In order 

 to malie sure that the under running of \;ater is prevented, the ground about the sluice must 

 be carefully and fimly ta.iped in. 



To reacl'i the vertical shank an easily re.-.iovable runv;ay plar.k is later laid from the 

 daiii to a bracket nailed to the vertical sliank (Fig. 11). In m;f experience the described 

 arrangement of the sluice is by far the most suitable. It makes a special fortification of 

 the fish ditch in front of the sluice superfluous. An endangering of the free standing 

 shanl: by ice pressure need be considered only v.lth trout ponds and vdnter ponds, but mostly 

 it does not happen because no strong ice foniiation occurs in the ilov/ing v;ater about tne 

 sluice, hov/ever, it can be easily removed. The fastening of the vertical shanlc to the dam 

 (Fig. 11) is unpractical, because according to experience, v;ood is most rapidly destroyed 

 by contact rlth earth or air. Installation of the vertical shank v.ithin tlie dam liker.lse 

 brings disadvantages. Ixitting easily starts in r;ooden sluices and supervision is made more 

 difficult. ;;csides, the vertical shank in this case must be at least v;ide enough so a man 

 can climb in. The free standing shank finally is not less protected than the other con- 

 structions from injuries by subsequent earth movements. 



67 



