20 



and leads into a fishpond constructed by M. Lesca at 

 Jaquets on the western shore of Arcachon basin ; here, as 

 may be easily discerned in the view, are two twin sluices 

 side by side, each with a single substantial shutter, 

 worked by an ordinary screw. In all the other views 

 reproduced two narrow twin shutters are fitted within a 

 single sluice way, a method inferior to the Jaquets plan 

 as the doubling of the sluices minimises the danger of 

 mishaps and permits of greater rapidity in the carrying- 

 out of the different sluice operations. 



Figs, i and 2, plate II, show the operation of faire 

 boire, the inflow of seawater into the ponds. Fig. 1 is 

 of the inner or pond end of the sluice, fig. 2 being of the 

 opposite or seaward extremity. The former view shows 

 the inner screen and one of the sluice shutters lifted 

 clear of the channel of the sluice ; the distended mouth 

 end of the sleeve-net may also be discerned immediately 

 under the raised screen. Angling for bass attracted by 

 the inrushing current is going on briskly under M. 

 Garnuno-'s direction. Fief. 2 shows further details of 

 the operation of faire boire while fig. 3 shows a view of 

 the same end of the sluice during the converse operation 

 of deboire. Note in this photograph the low state of the 

 tide as compared with that shown in fig. 2 ; also that 

 in this operation the sluice shutter is raised very slightly. 

 The next views, figs. 4 and 5, show closed sluices. In 

 fig. 4 the frame of the sleeve-net is seen raised and the 

 net itself carried back and thrown over the upper frame 

 work of the sluice gates. This position of the sleeve-net 

 is shown again in the case of the Jaquets sluice, fig. 6, 

 where it will be noticed that the gradient of the embank- 

 ment is considerably easier than in the case of those seen 

 in the other views. This is due to the fact that the soil 

 at Jaquets is composed largely of sand and is therefore 

 less easily consolidated than the clayey alluvium at the 

 mouth of the Leyre. 



