The Birmingham age-herald., 1907-12-23
One of the Deepest HaTbors In the World Opened Up
 h Lower Mississippi
GREAT WALLS BUILT
 IN SOUTHWEST PASS
Tremendous Difficulties Have Been Overcome In the Construction of the Jetties Which Has Cost a
 Total of $2,7oo,oo

New Orleans, December 22.-One of the greatest channel making under takings in the history of American nearly to completion this week when the jetties at the mouth of the South west Pass of the Mississippi river are finished. These jetties, after some dredging between them Is completed, will give the south one of the deepest harbors in the world by opening to tho access of the largest steamships ahoat the 100 and 2oo-foot depths of the low CT Mississippi river. The harbor thus made accessible has navigable water connection with at least dozen states bordering the Mississippi and its trib- utaries, the Ohio, Missouri, Arkansas and Red rivers About $60OO, 900 is being spent on this improvement by the United States government, which has the work in charge.
 Four Years of Work.
 The new jetties were begun four years ago. They are on larger scale and more substantial than the famous jetties at the Mississippi's' South Pass, an outlet which for over 30 years has been the rivers commercial entrance. They are nearly parallel walls, one about three and the other about four miles long, lying over half mile apart and bnilt in the shoal water at the Janctufe aof the pass with the Gulf of Mexico. Their purpose is to conf1ne and thus accelerate the rivers current across a mud bar about three miles broad, so as to produce a channel at least 1000 feet wide with a minimum depth of 35 feet. The swift current which they have produced, aided by dredging, even before their comple- tion, has caused tremendous SCOUT and has already made 50 to s5 feet of water In some places where at the beginning of the work the depth was but little over mans head. To make the uniform contract depth, there is still in several spots about 10 feet of mud to be removed. It is expected that the high water due within few weeks will sweep the remaining mud deposits out to sea by the beginning of next summer.
 Many Difficulties.
 Probably few walls ever have been constructed under greater difficulties t1dH we're tHeSe JetlltS. IDey are Udut of willow, scant1ing, stone and con crete. Although in some places they are not six feet deep and although their greatest depth IS barely Is feet, they have cost $2,700,000. Every material entering into their construction has been brought from distances of 100 to 500 miles. The jetties have no foun- dation. but rely for stability upon heir extremely broad bases, being from 100 to 150 feet wide at the bottom. In contrast to this great width of base, the concrete capping which forms the top of the jetties and which is the work receiving It's finishing touches this week, is but few feet wide. The capping Is a sea wall four and half feet high and Is the only portion of the jetties not submerged. The wall weighs between two and three tons per linear foot. The submerged structure supporting this mass of concrete is made almost entirely of willow poles and brush. With the aid of frame works of scantling. the willows were formed into so-called mattresses; broad, fiat structures resembling bed mattresses in form, each about two feet thick, 200 feet long and varying in width from 35 to 150 feet. The mat tresses were sunk one above the other. with the widest at the bottom and those above uniformally diminishing Tn width as they approached the surface. The topmost mattresses were uniform ly 35 feet wide and on level with the surface of the water Heavy broken stone was spread evenly over the mat tresses to sink them, so that a layer of stone rests between each of these willow structures. The greatest num- Der of superimposed matteresses was five.
 Securing the Channel.
 The Mississippi has done some very interesting work in addition to SCOUT ing out a channel, for 1t has made the mattresses practically indestructible to any normal agency of nature In th1s region by burying them under nun dreds of tons of mud. These deposits follow closely the contour or the Jet ties. in conjunction with which they form new banks of the river. The only change likely to occur in the jetties is their gradual sinking untli III tilne the concrete capping entirely disap- pears. This sinking already has oc- cured to the jetties at South Pass.
 Tn the course of many years new bar may form by silt deposits In the gulf in the now deep water beyond the mouth of the Jetties, and then the remedy will be the extension or the tetties a short distance further. me rate of bar extension during nearly 70 years preceding the starting or the jetties was between 15O and 2ao rect annually. and the deposits respohfloIe for this advance were made when con- ditions. now greatly changed. favored such accretions.
 Part of the s6.OO0.o00 allotted to making the channel Is being spent in safeeuards several miles above the jet ties to prevent any increase in the flow of other large outlets from the main river to the gulf. This is being accomplished by placing stone covered mattress sills on the river bottom across the entrances to those outiets' Several small bayous leading from south west Pass to the gulf will be en- | oIa rrn