C ) 
On this work there are built three thkk Walls a crofs rt^ 
go from one end of the Caufey to the other , founded upon the 
Body of the Mafonry , and running into the work of the Gallery,- 
which they traverfe crofs-wife. They are ancred and enchafed, 
on the right and the left, in the rocks of the two skirts of the 
Valley. The/r/?Wall, which is at the beginning of the Caufey, 
is 1 2 feet thick at the end , being much broader below by reafon 
of the tdu> or Hope : It is to be but 1 2 fathom high. The fec^nd^ 
to be more raifed, is 3 fathoms thick, and 2 5 fathoms high : It 
ftands very near in the midft of the Caufey , 3 3 fathoms diftant 
from the firft* The thirds which maketh the foot of the Caufey, 
and is 31 fathoms off from the fecond, is 8 feet thick, and 
1 5 fathoms high. The empty fpace between the firft and fecond 
wall is to be filled with (tones and earth well ramm'd together 
and made even,fo that it may be cover'd with a bed of loam 6 feet 
thick, floping, and infenfibly defcending from the fecond to the 
firft Wall ; that fo the water, that fliali be made to fwell to the 
height of 20 to 25 fathoms , fpreading it felf upon this glacis ov 
flope, and to lean every where on its center , may not fpoil the 
Caufey. In the like manner is to be filled up th^e empty fpace 
between the fecond and third Wall , defcending alfo flope-wife 
from the fecond to the third, to ferve f jr a buttrefs to the fecond, 
that is to bear all the weight and force of the Water. 
All thefe WaUs,and even thofe of theGallery,are to be counter- 
walled by a Wail of two feet thicknefs, Befides, the Gallery 
is to be counter-vaulted by another Vault ; and the intermediate 
empty fpaces are to be done up with a clayie earth well ramm'd ; 
that fo, in cafe that by any extraordinary accident the water 
Ihould come to make any gap in the loam-bed, that is betweea 
the firft and fecond wall, the reft may by this means be pre- 
ferv'd entire. 
In the firft Wall there are Stones in toothings, from the cop t(^' 
the bottom, on the right and left of the Aquedufts mouth, 
and of the Galleries window: And this is to make a Cavity 
chamber-wife, four foot fquare. The Wall of this little 
ftrufture is to be fix feet thick, counter-walled with another, 
Wall two feet thick , with a loam-bed between , to keep it 
fafe. Itfliall end on the top above the Gallery, flopc-wife 
U u u u 2 ar4 
