156 
NATURE 
[ DECEMBER 17, 1896 
FASCINE TRAINING AND PROTECTION 
WORKS. 
N the Engineering Magazine (New York) for June is 
an interesting illustrated article on “‘ Bank Revetment 
on theMississippi,” with illustrations showing the condition 
of the banks of the river after “caving” and the method 
of making and fixing the fascine mattress work used for 
their protection. 
The lower part of the Mississippi runs through a vast 
alluvial plain, the surface of which is below the level of 
the water in the river in times of flood. This land is pro- 
tectedj by banks locally known as ‘“‘dykes” or “‘levées,” 
which«prevent the flood water from inundating the district. 
The first of these banks was built at New Orleans in the 
early part of last century. 
earth taken from surface of the ground close by, and are 
constantly liable to damage by floods. Some of them 
are of considerable dimensions, and of sufficient width at 
the top to form a roadway for carts and other vehicles. 
From time to time these banks have been extended until 
Fic. 1.—Details of Hydraulic Grading. 
there has been developed the great levée system which 
-extends nearly from Cairo to the Gulf of Mexico, protect- 
ing an area of about 30,000 square miles of rich land 
-and numerous towns and villages, and guiding the floods 
in a permanent high-water channel to the sea. 
These banks are a constant source of care and anxiety 
to those who have charge of them, being subject to 
“caving” caused by abrasion; the action of soakage 
water ; and the undermining of the foot of the slope by 
‘the current. To prevent this caving, and for the repair 
of the bank, where it has taken place, brush and stone 
revetments are used. The material for this purpose is 
principally live willow or cotton wood poles from 25 to 
30 feet long, and fascines fastened together in the form of 
mattresses by iron wire. Norevetment work in the world 
approaches the magnitude of that undertaken on the 
Mississippi. Here mattresses, having a superficial area 
of seven or eight acres, are sunk in the bottom of the river 
in depths of from 80 to roo feet, and in currents flowing 
at the rate of from 4 to 5 miles anhour. Dykes 430 feet 
NO. 1416, VOL. 55 | 
They are constructed of the | 
} 
long by 60 feet high, containing 80,000 feet of lumber, 
2000 tons of rock, and nearly 20,000 lbs. of iron wire and 
rods, are placed in the water in a depth of 150 feet. 
The mattresses are constructed by first building on 
floating ways a rigid head of poles, to which weaving 
poles are fastened at right angles. On these, woven 
willow brush is laid ; a grillage of poles is then fastened 
to the top, and after being secured to the bank and 
mooring-barge, the mat, goo feet long by 150 feet wide, is 
sunk by means of large stones thrown from the barges. 
After sinking the mat the upper portion of the bank is 
levelled to a regular slope by what is termed an 
“hydraulic grader.” This machine consists of a pump 
having a discharging capacity of 2000 gallons a minute, 
fixed on a barge. The hose from this pump terminates 
in a 14-inch nozzle, from which the water is directed on 
the bank at a pressure of 160 lbs. on the inch, reducing it 
to the required slope. By this method the excavation of 
one cubic yard of earth takes a fraction less than one 
cubic yard of water, and uses 3lbs. of coal. The height 
of the bank thus graded often averages 30 feet, and the 
material removed along a length of 
100 feet, about 3500 cubic yards, cost- 
ing about 4 cents (2¢.) per yard for 
removal. When the bank is levelled 
and dressed to the required slope, a 
revetment of two layers of brush, 
with pole grillage above and below, 
fastened with wire and spikes, is placed 
thereon and then covered with stone. 
Another method of protection is by 
fascine mats made of bundles of poles 
3 feet in diameter, laid normal to the 
bank ; to these is fastened at intervals 
of 8 feet a 5/16-inch wire cable and 
q-inch wire strand. Fascines 11 
inches in diameter, made of bundles 
of willows, are then placed parallel to 
and against the head, and held in 
place by a turn of the wire, and the 
operation repeated until the desired 
size is attained. These woven mats 
often have dimensions of 300 by 1000 
feet. To build and sink a fascine 
mattress 300 feet wide, requires from 
250 to 300 men, and the average 
progress per day is about 150 lineal 
feet. Of the finished cost about 45 
per cent. represents labour, and 55 
per cent. material. 
The article in the Engineering 
Magazine only deals with fascine 
work as applied to the maintenance 
and repairs of the banks of the river. 
The jetties at the mouth of the Mississippi, con- 
structed for the deepening of one of the outfalls of 
the river into the Gulf of Mexico, for the purposes 
of navigation, were constructed entirely of fascine 
mattresses. In order to improve the depth from the 
gulf into this magnificent river, which has a navigable 
water-way extending over 16,000 miles, Captain Ends 
advised the training of one of the principal outlets, 
and so by confining the water within defined limits, and 
increasing its velocity and scouring power, to obtain 
greater depth. He undertook to carry out the necessary 
works to effect this purpose without receiving payment 
unless he succeéded in obtaining a channel 200 feet wide 
with an average depth of 26 feet, and a central depth of 
30 feet. This he successfully accomplished. The east 
jetty is rather over two miles in length, the other being 
a little shorter ; the effective width between them is 700 
feet. The mattresses used in the construction of the 
jetties were made principally of willows brought from the 
swamps over distances varying from 20 to 300 miles ; 
