[29] OYSTER CULTURE IN MORBIHAN. 971 
To lay small strips of wood in the passage-ways through the parks, 
would have been expensive in the beginning and useless in the end. 
Fixed obstacles would have created eddies, and the eddies would have 
induced a deposition of mud. The desire to examine the oysters would, 
consequently, have resulted in their being destroyed by the mud. 
Then arose the ingenious idea of covering the parks with coarse gravel, 
such as the shores afford. This gravel partakes of the well known 
property of sand, in distributing pressure over a large area. Slightly 
compressed mud is elastic, and vibrations are carried through it in 
great undulations. These two properties of distributing pressure and of 
elasticity have been judiciously utilized. 
Dr. Gressy was the first to employ this mode of consolidating the mud. 
“The first attempt at macadamizing,” says he, ‘‘were made in my 
parks. It is effected by spreading over the mud, to be hardened, a layer 
of sand, varying in thickness according to the softness of the mud. The 
sand becomes incorporated with the mud and thus transforms it into 
firm ground. I thus converted into excellent oyster bottom some soft 
mud, upon which the workmen had refused to work. 
“The macadamizing of mud by means of sand is, in my opinion, a 
discovery of great importance for the future. I call the attention of 
the commission in a special manner to this question, of which the oyster 
culturists have not yet understood the importance.” 
The Baron de Wolbock, who encountered the same difficulty, ex- 
presses himself thus: 
‘‘ Before utilizing the basins, it was sometimes necessary to excavate 
the rocks, and sometimes to harden the shifting mud, especially in the 
great basin of Keriolet. This was considered an impossible undertak- 
ing; nevertheless this result has been completely attained, by the use of 
sea gravel, spread upon the surface to be hardened. Put on in layers, 
from four and a half to six inches thick, this sand or gravel mixes with 
the mud, which it hardens, forming a sort of mortar, and this without 
changing the original level of the bottom. After this operation one can 
move about, and even place heavy loads upon the bottom, where pre- 
viously both men and apparatus would have disappeared, swallowed up 
in a short time.” 
Reverting to the properties of mud and sand already indicated, it will 
be seen that the consolidation with gravel has the great advantage of 
‘causing no modification in the section of the bed, which assumes greater 
consistency without change of level. The other means employed for 
the same purpose, such as fascines, which we have examined at the Span- 
ish fort, in the river Auray, are inferior both in effect and result. It is 
true that the particularly unstable nature of the bottom there may 
justify the use of fascines, but gravel and sand have such remarkable 
properties that, when judiciously employed, they are of a nature to bring 
about the most excellent results in almost all cases. 
