THE OYSTER. I3I 



form and extent, but generally with an area of about 

 two to three hundred square yards. Situated at a 

 short distance from the sea, and with the waters they 

 contain at a higher level than the mean height of ordi- 

 nary tides, it is only at the period of the spring tides, 

 or at each new and full moon, that the, sea rises to 

 their level and supplies them anew with water. The 

 best claires are those which receive water periodically 

 from the sea, during about three days before and three 

 days after each highest tide. This period of renewal 

 for the claires is that which experience has found to 

 be the best, and it determines the maximum altitude 

 above the sea for the construction of these reservoirs. 

 *' Around each claire is built a levee or dirt wall, 

 called 2, yard ^ about one yard in height and thickness. 

 This yard retains the water filling the basin, and upon 

 it the workmen pass to and fro in inspecting and 

 working the claire. A floodgate closes a sluice in 

 one side of the wall, by means of which the sea water 

 is admitted to the basin. This gate also regulates the 

 height of the water within the basin, and if desired the 

 basin can be entirely emptied by opening it wide. All 

 around the inner circumference of the yard a continu- 

 ous trench is dug to receive the mud deposited in the 

 basin from the stagnant water, for if this mud should 

 be left in the basin the oysters would soon be smoth- 

 ered. In order to facilitate the clearing away of the 

 mud into this ditch a slight slope is given to the bot- 

 tom of the basin, circumscribed by the ditch, from the 

 center towards the borders, so that the surface is 

 sensibly convex. Some breeders dispense with this 

 ditch, in which they are probably wrong, for if it does 



