Jalifornia ional HI 1013 12th St., Oakland, Cal. THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA LOS ANGELES GIFT OF John S.Prell L. M. Clement. PRINCIPLES AND PRACTICE EMBANKING LANDS PROM RIVER-FLOODS, AS APPLIED TO "LEVEES" OF THE MISSISSIPPI BY WILLIAM HEWSON, CIVIL ENGINEER ; ASSISTED IN THE ENGINEERING REMARKS BY CONSULTATION WITH M. BUTT HEWSON, ESQ., CIVIL ENGINEER, LATE CHIEF ENGINEER OF THE CENTRAL RAILROAD OF MISSISSIPPI. &C., tC., JcO. JOHN S. PRELL Civil & Mechanical Engineer. SAN FRANCISCO, CAL.^VJ^ NEW-YORK : , PRINTER & STKRKOTYPEB, 43 Centre Street, N. i.' Librmry TC T O THE HONORABLE JAMES L. ALCORN, C HAIR M A N OF THE SUPERIOR BOARD OF LEVEE COMMISSIONERS FOR THE STATE OP MISSISSIPPI, &c., &c., &c., THIS WORK IS DEDICATED BY HIS FRIEND, WILLIAM HEWSON. 733415 NEW YORK, SEP. 15th, 1858. To the Hon. James L. Alcorn, Of Mound Place, Coahoma County, MISSISSIPPI. MY DEAR SIR : As father of the Levee-system, in at least that State, you are, on public grounds, the man of all others to whom ought to be dedicated the following results of my reflections and labors on the Levees of Mississippi. As a Legislator, as a County Commissioner, as a general Commissioner, for the conduct of those improvements, your zeal, energy, and talent, have 'con- tributed, in an eminent degree, to the present matured prospects of the mobt important material interests of your State the drainage and reclamation of the great Valley of the Yazoo. As an agent, under your direction, in the accom- plishment of that great result, I am bound, therefore, to lay at your feet this summary of the views and rules by which I have been guided in that agency. As a private friend, however, you of all my friends in this country, have the first claim on my feelings. Truthful, warm, and disinterested, as I have ever found you in our long and somewhat trying intercourse, it affords me cordial pleasure to give public evidence, by even the dedication of this vol- ume to you, of my profound conviction of your truth, warmth, and disinterestedness as a private friend. While your qualities of head in the capacity, the courage, 6 the integrity, with which you have managed the public inter- ests committed to your care command my unqualified respect, it is privately a pleasure to me as publicly it is a duty to inscribe to you, as I here do, this result of my expe- rience and reflection on River-embankment. Accept it, my dear Colonel, as an humble expression of the honest regard of your ever faithful friend, WILLIAM HEWSON. P. S. Two years ago, this volume was commenced ; though in the intervals of leisure occurring under active engagements of my mind, it had not been completed until to-day. PREFACE, IMMENSE public wealth is being" accumulated behind the Levees of the Mississippi. From Cairo to the Balize, millions of acres of the finest land in the world are being- reclaimed from the Bear and the Panther, to bring- forth fruit for the enrichment of the American Union, and the luxury of private industry. Millions of money have already been expended on the works, behind which this great investment of enterprise of labor and capital is going" on ; and yet. up to the present hour, these expendi- tures have been made, to a great extent, without reg-ard to the teaching's of a regularly dig-ested experience. This book devoted to the Levee, and to Levee interest is, therefore, given to the public, the first attempt to reduce to order and to rule, the design, execution, and measure- ment of the Levees of the Mississippi. Hundreds of thousands of people are concerned to the extent of their fortunes if not, even of their lives in the subject treat- ed of here ; and hence is it unnecessary for the author to 8 PREFACE. apologize to the public, for an attempt to reduce a subject of such immense importance to an exact popular rationale. The necessities of a country so new as that along- the Mississippi, place the management of its public works in the hands of unskilled men. This fact, coupled with others proper to the case, commits the execution of the Mississippi Levees to the inexperienced good sense of the planter, or, less safe guide, to the inexperienced manipulations of the laborer, the wood-chopper, the me- chanic, who succeeds in obtaining 1 from that planter employment as a Civil Engineer. This condition of things, is, under all the circumstances of the case, to some extent unavoidable ; and in order, therefore, to make it comport as far as possible with the proper man- agement of the Levees, this summary of the principles and practice of Leveeing, is made in terms equally intel- ligible to the professional short-comings of those " En- gineers," and to the popular knowledge of those planters. Those gentlemen who, engaged on the Mississippi Levees are, in fact, Civil Engineers, will doubtless receive this humble volume favorably. They will, it is hoped, find something in it that may assist their labors directly, and much that will tend to strengthen their influence over the works, by convincing the intelligent planter, that those works are subjects of extensive reflec- tion and experiment in a certain department of know- ledge. This Memoir, humble as it is in its pretensions, will do good service to the profession, and to the public, if it PEEF A CE. 9 assist the parties interested in Levees to discriminate between the educated Engineer and the untrained pre- tender. This volume contains a short review of the History of Embankments. Natural Phenomena of Rivers have also been considered in it briefly, especially those phenomena bearing- more directly on the theory of Leveeing 1 . The Engineer and Levee Commissioner will find these heads of some value for their own guidance, and also, in obtain- ing- that co-operation for their plans, which must always follow from enlightening, on the subject of those plans, the population living behind the Levees. The principles of Economy and Usefulness, touched on in this part of the subject, will be of great importance to the Engineer and to the Commissioner, in indicating use- ful reforms in the present system of Levee manageme.it and construction. The Earth-work tables included in the following pages, will be found of general interest. They embody a new system of obtaining, by inspection, the areas of Earth- works in exact accordance with the prismoidal formula. They are alike applicable, as far as they extend, to the prisms of the Levee-bank, the Canal-bank or cut, the bank or cut of the Railroad. For slopes of a varying rate, or of greater extent than those given in the tables, the plan pursued in the preparation of those tables is equally applicable ; and is, therefore, highly valuable to the practical Engineer, as a means of simplifying to an extraordinary extent, the laborious reference necessary in such tables as Sir John McNeill's, for calculating quan- tities by the prismoidal formula. 10 PREF A C E. The Contractor on Levees is highly interested in the publication of the Earth-work tables included in these pages. Ignorance and carelessness have, too generally, characterized estimates of the quantities of Earth-work executed in Leveeing; the consequence being, some- times, large losses to the contractor, sometimes large losses to the public. These tables, placing the facts within the reach of both parties, guarantee, therefore, justice in all cases to each. The use of the tables as explained in the letter-press, is short and simple. Men of ordinary intelligence, knowing the heights of a Levee, at intervals of 100 feet, can tell with accuracy by those tables the solid content of the Levee. The Commissioner, the Engineer, the Contractor, and the Public, can, there- fore, bring these results within the compass of the popu- lar knowledge. CONTENTS. 11 CONTENTS, CHAPTER I. SKETCH OF THE HISTORY OF- EMBANKING, 13 CHAPTER II. NATURAL PHENOMENA OF RIVERS, ....... 22 CHAPTER HI. THE LEVEE, 53 CHAPTER IV. DETAILS OF LEVEE WORKS, 79 CHAPTER V. HIGH WATER MARK, 102 CHAPTER VI. LOCATION, 106 CHAPTER VII. SURVEYS, 116 CHAPTER VIII. ADMINISTRATION, 121 CHAPTER IX. EARTH-WORK CALCULATIONS, 134 THE TABLES ... 15& PRINCIPLES AND PRACTICE OP EMBANKING LANDS FROM RIVER-FLOODS. CHAPTER I. SKETCH OP THE HISTORY OP EMBANKING. " LEVEEING " Embanking as it is generally called to confine rivers within their banks, and bar the approach of the sea, and its sister system of back-drainage, have, from a very early period, occupied the attention of individuals, governments and peoples. The Phoenecians, Babylonians, Egyptians, Romans, Hindoo- stanees, and other East Indian nations, embanked low lands and drained marshes. Those nations chiefly inhabited alluvial plains, which, by their superior richness of soil when reclaimed, amply repaid them in the abundance of their crops, at less labor than was necessary to expend in the cultivation of higher districts. History informs us that the Babylonians and Egypt- ians were the first to adopt the system of reclaiming waste lands by embankments. The low ground in the midst of which the city of Babylon, was built, affords an early instance of the necessity of embank- ing ; and consequently taught its inhabitants the principles of construction in earth works. The causeway thrown up over the 14 PRINCIPLES AND PRACTICE OF low grounds, on each side of the Euphrates, leading to the cel- ebrated bridge over that river, is the most remarkable, because it is the most ancient, of which there is any record. Egypt, the land of floods and marshes, from the richness of its soil when reclaimed, was enabled at known periods of his- tory to supply during times of dearth the impoverished nations around with corn. Egypt, when subject to Rome, was the granary from whence supplies for that city were drawn. About 2320 years before the Christian era, the greater part of Egypt was an extensive marsh, which Men6s, the then-reigning King, undertook to reclaim. He diverted the course of the Nile into the middle of its valley or " bottom lands ;" cut water- courses and raised embankments to confine the waters within them. His successors, each in his turn, made similar improve- ments raised mounds on which to build their cities, above overflow, and cut canals for irrigation. The celebrated Lake Moeris is represented as one of the most remarkable works of ancient Eygpt ; and is supposed to have been executed by a King of that name ; and finished about 1385 years B. C. This Lake was according to Herodotus 450 miles in circumference, and is said by some to have been in places 300 feet deep. * By means of * This summary of the great drainage works of the past follows without question the statements of History. Here, however, it may be observed that this Lake Moeris story seems to be one of the most preposterous inventions of even Herodotus. -The pumping necessary to keep such an excavation dry is with even all the appliances of steam an inconceivable feat. The lifting and moving performances of the ancient Egyptians are truly wonderful, but how they could have hauled the infinite volume of excavation from such a "pit" as Lake Moeris, with an average haul of some 30 miles is beyond all comprehension. Waiving, however, these difficulties, the story is absurd. At an average depth of 150 feet one-half the alleged maximum depth the earth moved from Moeris would represent a content of 2,400,000 millions of cubic yards. Supposing the Egyptians furnished with the improved tools of modern ex- cavations, this work at the rate of 5000 cubic yards per man per year, would have consumed for "loosening and lifting" the labor for 12 months of 480 millions of men. Done as stated in the reign of King Moeris, if it be supposed that he reigned for even EMBANKING LANDS FEOM KIVEK-FLOODS. 15 a canal it was supplied with water for six months in the year this water during the remaining six months returning to the river by a regular system of irrigation throughout the whole extent of Egypt ; thus supplying the land with moisture during the dry season. This Moeris Canal, in itself a stupendous effort of art, is still entire. It is 40 leagues in length. There were two others also in connection with the lake having sluices which were shut and opened alternately as the waters of the Nile varied in elevation. The ancient Romans were more remarkable for the extent of their embankments, and the energy and skill put forth for the reclamation of submerged lands, than any other nation before their time. They appear to have been the special guardians of the swamps and marshes of Europe. The inducements to this guardianship lay in the great superiority and richness of those soils as compared with the more elevated districts. The Romans embanked the Tiber near Rome, and confined the waters of the Po in a similar manner for many miles from its embouchure. Remains of their embankments are to be found in Holland, in most of the Fen-districts of England, and in other countries where their indomitable energy and perse- verance carried them. India presented originally great difficulties to culture. Its physical and its atmospheric character combine to present for- midable draw-backs to natural production. Consisting largely of alluvial flats, the suddenness of its monsoon-rains, the short duration of those rains, and the long duration of the succeed- ing drought, place cultivation completely subject to these two conditions irrigation at one season of the year, and drainage at another. Embankment is the prime means by which these 48 years, the work must have employed for that period in digging ale ne 10,000,000 of able bodied laborers ! 50 millions of people must therefore have lived on the works, and a like number have been employed feeding them. 16 ' PRINCIPLES AND PRACTICE bF have been accomplished ; and these embankments, or, as they are called in Hindostan, " Bunds," are the great artificial agents that have conferred the teeming luxuriance of the present state of that country on the soil of India. The " Bunds" of India, while damming back the floods of the monsoons from the rich flats behind them, run in double lines ; and by confining between them the waters of those floods, reticulate Hindostan with numberless canals. Naturally, these waters would escape at periods of overflow, through a few rivers ; but, distri- buted through numerous canals, they are retained on their passage to the sea sufficiently long to answer through the dry season the purposes of irrigation. To husband the too-copious monsoon-rains, the natives have built " Bunds" of great magni- tude across river-vallies and streams, thus forming artificial lakes or reservoirs, often of vast extent, as storehouses, to supply the wants of a dry season. From these the water is conducted for miles along the flanks of mountains, across gorges and vallies, and through the most difficult countries, irrigating the land in its descent. Taught by the necessities of their country, the East Indian nations of by-gone ages have left behind them the remains of works of irrigation monu- ments of their greatness unsurpassed even by Egypt. One of these on the Island of Ceylon, an evidence of the enterprise and public spirit of the Cinghalese monarchs, is a good speci men of such works. It was formed of huge blocks of stone, strongly cemented together and covered over with turf, a solid barrier fifteen miles in length, one hundred feet wide at base, sloping to a top width of 40 feet, and extending across the lower end of a spacious valley. Egypt was undoubtedly the cradle of the sciences, and par- ticularly Hydraulics. It remained, however, for later times to arrange the laws of fluids into well defined formula. This science seemed to lay dormant for many hundred years : and EMBANKING LANDS FROM RIVER-FLOODS. 17 it was not until during the eleventh and twelfth centuries, when it was thought necessary to make several of the Italian rivers navigable, and to cut canals for drainage and irrigation, and in the thirteenth century, when the practice of embanking and confining the rivers of Italy within their banks, was adopted, that it can be said to have claimed the attention of the learned. Before the seventeenth century there was scarcely any known digest of principles, by which, to carry out the works of the Hydraulic Engineer. In the year 1665, a Congress of the most celebrated scien- tific men met in Tuscany. At this Congress it was proposed by Cassini and Yiviana, to confine the Chiana by banks, and so conduct it to the Arno. During a subsequent meeting, at which Torricelli was present, the embankment of the Chiana was recommended on the ground that the rivers Arno, Tiber, and Po, were confined by the same means. At this period, practical Hydrodynamics received a great impetus ; congres- sional meetings of scientific men were held, which, under the necessity of reclaiming all the submerged lands of Italy, called out the energies and talents of a host of the ablest philoso- phers of the age. The experience, experiments and writings, brought forth under these circumstances laid the foundation of our knowledge of Hydraulics in nearly all its branches. Amongst the distinguished men contributing at that time to this subject, were Gallileo, Torricelli, Guglielmini, Poleni, Manfredi, Zendrini. A general system of embanking rivers, as a consequence of this movement amongst the savans of the day, was adopted in Italy, so that the Po, Adige, Tiber, Arno, Reno, and their tributaries are now confined between high, artificial banks. Italy, from the peculiarity of its physical character, seems adapted by nature for the cultivation of this science. Lofty mountains, frequent rain-falls, heavy snow-drifts, break the 18 PRINCIPLES AND PRACTICE OP region of the Alps and Appenines into, frequently, foaming torrents, torrents that, descending with headlong impetuosity to the more level country on the sea-board, pour destruction upon town and field. Along the low lands of the Po, perhaps the most fertile section of all northern Italy, from the destruc- tive character of its precipitous floods, immense changes have taken place from time to time. The river has frequently changed its course, filling lakes and marshes, destroying towns, and causing immense devastations. Hydraulic Engineering has executed its first systematic works on the drainage of the Po ; and the nations of modern Europe have received there- from, knowledge which enabled them to carry on similar works. France, Spain, Holland, Germany, England and Ireland, are thus alike indebted in this department of practical science to Northern Italy. And, now, embankments which reclaim im- mense bodies of rich land abound throughout all Europe. Holland is well known to be low and flat. The alluvial de- posits brought down, before even the dawn of History, from the higher districts of Western Germany and Northern France, by the Scheldt, the Meuse, and the Rhine, resulted in a marine swamp, known now as the "Low Countries." This once salt- marsh has been erected into the rich and prosperous Kingdom of Holland by "Dikes" or embankments. De Luck, in the first volume of his Geological Travels, says, " that the sea banks on the coast of the North sea, at the mouths of the Eyder and Elbe, extend to not less than 350 miles." And by another author, " the Southern shore of the North sea is embanked to the ex- tent of 600 miles, ths Southern shore of the Baltic for 1000 miles, and the Bay of Biscay to the extent of 300 miles." All the great rivers of Germany and Holland, such as the Rhine, the Elbe, the Oder, the Leek, the Vaert, the Yssel, the Maes, have all been confined to their channels by embank- ments. 'EMBANKING LANDS FROM RIVER-FLOODS. 19 The Zealand Dikes or embankments are said to be at least 300 miles in extent, and to cost for annual repairs, the large sum of $800,000 ! The sum expended for similar objects and for the regulation of the water-levels throughout Holland alone, amounts to $3,000,000 per annum ! The early history of embanking in Holland, Zealand, and other places, presents a series of calamities from the destructive power of water, almost unparalleled in history. England is probably indebted to the Romans for the first embankments on the Thames. " London" indicates by its derivation from the Saxon words " Lyn din," that it was once " the City of the Lake." And history tells us that it owes its existence to the drainage of its site by embankments. The fact, however, maybe settled without an appeal to history. It is well known that many of the marshes in the immediate vicinity of London now under consideration, as subjects for embankment, are 12 feet below high tide in the Thames. The original marshy character of the ground on which the modern Babylon like the ancient Babylon stands, is indicated also by the fact, that many of its streets terminate with the word " Wall ;" the names of several towns and places, such as Black- wall, Mill-wall, 1ifi.s to only those circumstances under which a tributary-flood i* discharged into the river-chan- nel at the period of a corresponding flood in that main channel. 32 PEINCIPLES AND PRACTICE OF from its own supplies. The conclusion arrived at is in truth this : a glut of water in the Mississippi will not be increased in level by the accession of other gluts, from the Ohio, Arkan- sas, feot Outside or wet slope 8J to 1. j C1 In Clay. Inside or dry slope Ij to 1. ) f . Outside or wet slope 2 to 1. \ "own 3 feet. The clay-section supposes the rejection from the bank of all sand. For any admixtures of the two, no matter how small the proportion of that material in the admixture, it would not be safe to deviate from the proportions recommended above for sand. In order to show the ease with which this new practice may be substituted for the present faulty one, the following form of calculation is presented here : Station. Height of Leveo. Inside slope. Outside slope. Crown width. Total width of haae. 41.40 46.20 43.80 58.80 73.20 81.00 67.80 45.60 To guard against mistakes in making this calculation, it is recommended that after copying from the field notes the heights corresponding to each station, each of the other columns be carried out separately. Otherwise the multiple of 2J in the one case will be often used by mistake for the other multiple and vice versa. 2J tol. 3J to 1. 1 6.40 16.00 22.40 3.00 2 7.20 18.00 25.20 3.00 3 6.80 17.00 23.80 3.00 4 9.30 23.25 32.55 3.00 5 11.70 29.25 40.95 3.00 6 13.00 32.50 45.50 3.00 7 10.80 27.00 37.80 3.00 8 7.10 17.75 24.85 3.00 EMBANKING LANDS FROM RIVER-FLOODS. 79 CHAPTER IV. DETAILS OF LEVEE-WORKS. EXPERIENCE is made up in Leveeing, as in all other works, of a knowledge of its details. Success in Leveeing, as in all other matter of practice, is regulated by paying due regard to small particulars. The intention of this contribution to the sys- tematizing of those works excludes from this book a full examination of all the specialities that have arisen in the course of my experience on Levees in both Mississippi and Arkansas. Particulars, such as occur often or involve important consider- ations, are perhaps not excluded by the general plan laid down for my guidance in these pages. Attention may, therefore, be directed to a few considerations suggesting themselves by the special experience of my Levee-works. In preparing the ground for Levee-base it is necessary to clear and grub the whole thoroughly, leaving neither stump, root, brush, weed, nor even grass. This important duty is generally done with great carelessness. Before the work of embankment is commenced, all the timber, roots, weeds, and grass removed from the foun- dation ought to be disposed of in piles and burned to ashes. This rule should be enforced rigidly. It is the only means of guaranteeing the exclusion of all unfit material from the body of the Levee. In Arkansas particularly, and in Mississippi to a very large extent, to place logs, brush, and even whole trees, in the body of a Levee was an impropriety of not exceptional 80 PRINCIPLES AND PRACTICE OP but of common occurrence. * In new Levees such an imposition can always be detected after rains by vertical holes in the crown and sides ; and in dry weather may be detected by piercing the Levee at intervals along the crown with an iron rod. The only certain means, however, of excluding from the Mis- sissippi embankments the materials grubbed and cleared from their base, is the enforcement of the rule that those materials shall have been burned in the presence of the superintendeni before the bank shall be commenced. In connection with this subject it may be observed here, that the clearing along the line of Levee ought to extend to all trees growing within their own respective lengths on either side of the crown of the Levee. All trees without that distance ought to be cut down ; but if this should be supposed a need- * The Coahoma Commissioner who has made himself thoroughly conversant with the scientific principles and practical facts of Levees in bearing testimony to the triumphant success during the late extraordinary flood of Levees properly planned and executed, calls attention to the cause of breaks being Logs, &c., in the bank. In his printed Address, of the 25th last July, that gentleman holds the fol- lowing language: " The question, then, is: did the Levee when properly built per- form the work for which it was declared competent 7 I say it did ; and challenge any man upon the whole line of Levee, on either side, to point to a single break where there did not exist a local causa." The address goes on to say : " But in the large majority of cases where breaks occurred, the water either ran over the top, or stumps and logs embedded in the work occasioned the break." One of the most general causes, however, of Levee-breaks during the late floods, has been the Craw-fish. This animal digs a hole through the Levee, from the water side, in order to obtain a passage through the small fish, or water insects passing in with the flow, furnishing the object and the reward of his labor as prey. In sand, the Craw-fish cannot carry out his purpose, for the hole when made falls in, the Craw-fish, accordingly, desisting in his work. Clay banks are well adapted for the operations of the Craw-fish, and though, essentially the best in all other particulars for Levees, are open to this grave objection ; this fact suggests that to obtain the general advantages of clay embankments in Leveeing, it is expedient in order to guard against its special disadvantages hi those works, to carry up within them a wall of sand. The experience of the late flood makes this sand-wall in clay Levees a detail of the first importance. EMBANKING LANDS FROM PJVER-FLOODS. 81 less precaution, it certainly is not so in the case of all such trees leaning in the direction of the Levee. This should be done during the clearing of the ground for the Levee, the trunks to be burned with the rest of the clearing-spoil. During high-water the falling of a tree, from either side, across the embankment, will cut down through the crown at least several feet. I have known one- instance where a large cotton-wood (4| feet in diameter) cut a 5| feet Levee to its base. If a simi- lar cut should occur during the flood season, on a high Levee, the water admitted through the gap so made would form a crevasse, sweeping away large lengths of the Levee, inundating the' adjoin ing plantations, and for the season of its occurrence, destroying the object of the whole system of Leveeing to the people and property of hundreds of square miles. But, besides the avoidance of this danger, the removal of those leaning trees, at first, is in fact less expensive than when they have fallen. Road-crossings are very frequently cut across Levees, in Mississippi, and elsewhere, during low-water. The planter immediately concerned is expected to see, at the proper time, that such a cut is duly filled ; but in some stretches of Levee, it often occurs that what is every body's business is no body's. Besides, this liberty with the Levee is bad in principle ; for it points directly to impunity, for infringements on the sanc- tity so to speak of the work in less dangerous particulars. Rows of Osage-Orange, or other hedge-shrub set along the base of each slope, will save the embankment, better than all the restrictions of law, from injury by either man or beast. In the absence of these hedges, however, it may be suggested that, to guard against the cutting of roads across the Levee, the best course would be, as in Holland, to raise the natural surface of the road-way by embankment from each side in easy slopes, to the top of the Levee. To slope down the Levee-level at a rate of even 20 to 1 to the level of the road en either side 82 PRINCIPLES AND PRACTICE OP crossing it, will, in general, require comparatively little work, the base of such an extra bank, exclusive of one-half the base of the Levee, being for crossing a Levee of 10 feet high, but in all some 370 feet. This road-way is, in Holland, termed " Ramp." The cost of this extra work is but small for securing the advan- tage of placing the continuity of the Levee beyond the acci- dents of local carelessness of placing the important principle of its inviolability beyond the infringement of popular necessity. Levees across creeks or bayous are very often made wide enough on top to constitute a roadway. The inviolability of the Levee comes in here again to object as an important principle against this practice. Besides that the course is objectionable on the ground of economy. The grassing of the crown as a saving of wear and tear is, with the supposition of the roadway, out of the question. If cattle-trespass on the slopes is to be excluded, it can be excluded with a roadway on the top by only the cost of four instead of two rows of hedges, two on each side of the roadway and two along each slope. The wear and tear of the whole Levee with the rut-cuttings of wheels in wet weather, and the slope-breakings of horse-hoofs in wet and dry weather, would make this roadway tell heavily on the Levee-account in increased outlays for maintenance. These objections apply with equal force to employment of Levees for roadways, whether along their whole length or for any part of that length. In the case of bayou crossings, or the crossings of other deep breaks in the general surface of the back-land, the roadway may be combined with the Levee without going to the extent of making them perfectly identi- cal. The following section shows a method of combining the roadway with the Levee at deep-crossings with, in general, less work a method, too, removed from the objections urged above against using the crown of the Levee for the purpose. The Levee here is assumed to be protected fully from tres- passers by the hedge-rows shown at a and b, the whole surface EMBANKING LANDS FEOM KiVKR-FLOODS. intermediate between these being protected by the proper coating of grass. The roadway, of course, is situated on the dry side, and as an extra to the Levee, may be left to the par- ties concerned in it as a road for its maintenance. Three- fourths of it may be washed or worn away without any incon- venience to the Levee. Improvements of this sort on the present practice must be regarded with the consideration due to everything pointing to a saving in public outlay in taxation. The general question of making Levees the site of the road- ways required for the traffic and travel taking their direction, is met in the foregoing remarks on Levee roadways. The gravest objection, as has been seen, applies to the location of roads on drainage embankments. Occasional travel even is so injurious that it ought to be avoided by all means where more efficient means are not employed by the collection of brush, briars, or other obstacles across the whole extent of the bank at intervals. These impediments are absolutely essential in new works on new locations ; for few men will be so scru- pulously observant of law as to ride through the tangled paths of a swamp when they may choose, in their stead, the open and unbroken smoothness of a Levee. The enforcement of penal- ties, under such circumstances, is difficult. The best remedy in all such cases, after that of impervious hedge-rows, is and for travel and traffic only, it is a perfect remedy the construction of a roadway within the Levee at a distance sufficient to save the berm from the contingency of encroachment by either hoof or tyre. This, with brush walls drawn across the bank at inter- vals, will save the Levee from all damage except that arising from the trampings of cattle and the " rooting" of hogs. The Osage-Orange, however, is infinitely better than an army of police and a volume of penal laws, for the protection of em- bankments from all trespass. 84 PRINCIPLES AND PRACTICE OF Excavations of the ground outside a Levee is objectionable. In sandy or other weak earths it is even worse so than in clays. Under any circumstances such cuts ought to be removed as far as possible from the berm of the Levee ; but never less than ten feet. The " pits" dug in such positions ought not to be continuous ; but ought to be divided from each other by walls preserving the continuity of the natural surface. Separ- ated thus from each other, those excavations will fill up the sooner under the depositions of floods. These breaks in the external cuts will also prevent them of becoming channels of flow ; and thus guard against the creation of avoidable current washes on the slope and berm of the embankment. The slope of those external pits should, on the side next the toe of the Levee, never be vertical, but always dressed off at an angle fully equal to that of the adjoining Levee slope. Left at a less slope, the pit-banks may faU in, and the falling so occurring will then advance until finally it shall have undermined at least a portion of the Levee itself. Trifling as this detail may appear, it is urged here as one which practical experience has pointed out as of great importance. Exterior excavations, then, for the construction of Levees should be made in pits separated from each other at intervals by walls, the inner slopes of these pits being never nearer the Levee base than ten feet, and never of a more rapid angle than that of the water- slope of the adjoining Levee. These precautions ought to be laid down expressly in Levee-contracts. Carried out practically they will save the work from the contingencies of its first and perhaps second year of trial ; but after that, the foreshore the ground outside the Levee will " warp" or " silt up" under the flood-deposits until the resulting elevation going on to the full height of high water mark, the foreshore side of the em- bankment will cost little or nothing for maintenance. Large Levees require in their construction especial care. As a general rule it may be observed of those works that the EMBANKING LANDS FROM EIVER-FLOODS. 85 heavier they are the weaker is their natural foundation. The twenty or thirty feet Levee in all cases within my observation implied a Levee, whether across swamp, bayou, or " old bed," having for its base a soil no stronger than shifting sands or watery puddle. All such Levees, on this consideration and on the further consideration of proper compactness and strength, ought to be carried up in regular layers of earth, each layer " dished'' out from the centre and tramped over by the hauling necessary for the next succeeding layer. These layers should not exceed three feet in thickness. Crusts thus carried up one after another from the base, assist to distribuie the press- ure of the whole equally over the whole base ; and thus in the case of weak foundations assist largely in the stability of the work. Hollowed out from the centre " dished" these layers or crusts of tramped earth fitting each into the one below it cannot shift under the lateral strain of high-water. After en- suring safety at first by carrying the bank up thus in layers, the whole becomes subsequently one solid and settled mass. The settlement allowance in banks so constructed is merely nominal. In connection with the stability of Levees across o^-discharging bayous, it may be observed here, that that stability is sometimes threatened, after all proper precaution in construction, by the accumulation of water on their inner side. The bayou having discharged outwards a mere trickle perhaps at the time of stopping it, soon accumulates to a con- siderable body of water, until finally the whole becomes ponded up against the sides and bottom of the bayou and the inside slope of the Levee to the height of the bayou bank. The additional load on the foundation over and above the Levee and the river flood-water, is in itself objectionable, though perhaps not quite so much so as might appear at first, when it is recollected that the distribution of the weight, front and rear of the Levee, would save the danger of " bulgings" up at the toe of the Levee the place of these bulgings being 86 PRINCIPLES AND PRACTICE OF always occupied by corresponding sinkings of the embank- ment. But the greatest objection of such pondings up is their continuance ; seeing that the longer they continue the more thorough and the deeper is the saturation of the underlying earths ; and the more thorough and deeper their saturation the greater the extent and the degree of the weakness or " meltings" of the earths in the foundation of the Levee. In order to guard against this evil, it is necessary that small cuts be run up through, or out of, such bayous to such a point as may be necessary to divert their drainage into the general out- fall of the surrounding country. All Levees across owMlow creeks or bayous have been observed, when this precaution has been neglected, to sink into their foundations ; and as a consequence to cost more than otherwise for their maintenance. Crusts of earth have been referred to already as means for the distribution over a wide surface, of superincumbent loads. In the case of a " muck ditch " cut along the site of the Great Yazoo Pass-Levee of 1855 cut against the express direction, if memory serve me truly, of the Commissioner and the Engi- neer the advantage of an unbroken crust of this sort was illustrated very strikingly. The division by the " muck ditch" having taken place under the line of greatest load, that load, pressing on the lips of the cut vertically, acted on them as re- marked in such cases on a previous page, with a leverage, until driven down step by step the crust must have become, by the consequent bending, broken near the toe of the Levee on each side. Two distinct pieces of crust were thus, in all probability, driven down angularly into the thin matter underneath ; and thus, instead of using every precaution to preserve the natural crust as a grillage under the bank, the Levee was left to seek its foundation as best it might amongst quicksands and fluid puddle. The weakness of the foundation told itself accord- ingly by not only the sinking of the crown of the embankment, but also by the bulgings of the slopes and the spreading of the EMBANKING LANDS FROM RIVER-FLOODS. 87 base " a corduroy " or causeway of logs near the inner talus having been forced by those spreadings from a straight line into a succession of zig-zags. Alarmed by the sinkage of his work a sinkage that, according to his estimate, was made naturally enough by one in such a position, to cover all the losses consequent on his own mismanagement the contractor became unmanagable. The Engineer recommended him to open a ditch of a few feet wide and of five or six feet deep inside and parallel with the Levee, in order, by filling up the same with the trunks of the young cotton-woods cleared from the base of the Levee, to present a breast work of equally bearing resistance on the dry side to the spreadings of the base the then-standing flood-waters on the wet side offering sufficient resistance to spreadings or bulgings on the wet side. A deep pit of sand furnished convenient drainage for the ditch so suggested ; and the excavations of the ditch would have been available for the completion of the embankment according to the contract. Instead of adopting this course, however, the contractor at- tempted to carry up the sinking Levee to the contract-height by removing the masses of earth bulged out on its sides and spread out beyond its base to the crown, heedless of the re- monstrance of the Engineer that in doing so he was merely revolving an endless chain. Every yard taken from the bulgings on the side and removed to the sinkings on the top, was speedily replaced by another yard on the sides, the top remaining in statu quo. Finally, however, the work was re- sumed at the base and carried up in closer conformity with the slopes ; and, all parts of the cross-section thus newly loaded, the crown carried up finally in " a comb " to exclude the flood then standing some 20 feet on the water-slope, the whole presented sufficient solidity, under all the unfavorable circumstances that attended its construction, to have dammed back that year's flood. This case fell within the practice of Mr. M. B. Hewson. Another case of weak foundation for a Levee came under the 88 PRINCIPLES AXD PRACTICE OP observation of that gentleman in the construction of the great Levee across the mouth of the Old Lake of Oldtown, in the State of Arkansas. The site of this Levee had, within the memory of men living in the neighborhood, been the bed of the Mississippi River ; and as such may be well supposed to have presented a foundation of a description the very weakest. A shallow stream running across the proposed line of work, the undertaking had not the advantage in some places of even the hard crust of the Yazoo Pass. The irregular course pursued in carrying out those works on the Mississippi confines generally its restriction on the contractor to the height, width at base, and width of crown, the means by which he fulfills those con- ditions being questions for only his consideration. Acting on the part of the State, Mr. Hewson had no voice as to foundation or any other obvious preliminary in a proper construction of the work. The contractor accordingly dumped in his earth without any preparation of the foundation ; and counting on pay for every yard so dumped, carried up the work by, simply ) force of purpose and labor. The centre frequently sank into the foundation. Standing sometimes for a couple of hours at its full height, it would drop down suddenly from 5 to 10 feet. The base spread to an incredible extent at all points but one that one being loaded heavily with an interlocked and tangled mass of logs, branches, and trunks, removed in clearing the site of the work. The spreadings having reached their utmost at all other points, the work was being carried up along the loaded length of the slope, when suddenly the tangled mass of timber loading it was torn asunder with a loud noise, and shot for some distance from its original position. The bulging that took the place of this weight on the base of the Levee was found by measurement to have been some 4000 yards ! Such are the forces exerted by such Levees ; and such the character of their foundations. The " sinkage," as it is locally termed, was, how- ever, in the case of the Yazoo Pass-Levee, a mere trifle in com- parison with that at Oldtown. EMBANKING LANDS FROM RIVER-FLOODS. 89 Weak foundations occur in the case of Levees, in only the cases of those important works that may be considered the Keys of the whole. The Yazoo Pass embankment once swept away, the whole extent of Levee remaining in the County of Coahoma would become, virtually, valueless to the parties living behind it as a protection from inundation. The under- taking of the Levee-system at all, involves, therefore, the necessity that all those more important points of the system be executed in a manner to insure, at least, as high a degree of stabil- ity as any of the less important, parts of the system. With some 30 feet of water standing on its outer slope at flood-time, its inner slope resting on the bed of a channel, of like depth, constitu- ting the arterial drain of the back country, the failure of one of those Key-works of the system, when occurring to even the smallest extent, involves its total destruction. The rush of water through the whole width of this Key-levee, under a head of some 30 feet, sweeps into the back country in a foam- ing torrent ; the whole system of back drains becoming, in the first place, suddenly charged to the lips ; and then, all the overflow passing off upon a surface deprived of out-fall, the country behind the Levee becomes, to a greater or less extent according to duration of the flood-level in the river, com- pletely deluged. On the other hand, a " crevasse," or breach in the general line of the Levee, may not only be stopped altogether before it arrives at any considerable width ; but at the worst, the depth of its out-flow not exceeding a few feet, the back lands pass off the water, through their system of back- drainage, at a rate, if not even quite as rapid as the in-flow, quite rapidly enough in the generality of cases to prevent the engorgement of the back-drains before the fall of the river- level. A breach in the Key-levees, then, involves a certainty of wide inundation ; while a breach in a less important part of the system leads to an inundation under the worst circumstan- ces, limited in its extent, and in its duration brief. But this 90 PRINCIPLES AND PRACTICE OP is not the only reason why it becomes necessary to con- struct Key-levees with special care. Costing, according to their present mode of construction at a rate so high, in some cases, as upwards of $60,000 a mile, whereas, the generality of Levees do not cost over $2,500 a mile ; a breach in one of those heavy works leading as it always does to its total demolition, results in a very serious loss of money. The destruction of Yazoo Pass- Levee was as great an injury to the treasury of Coahoma County as would have been the destruction of the whole embankment, from the junction with the Pass-levee to a point as far South as Friar's Point ! The Commissioner was very much censured by parties interested in the stability of this Pass-levee, for his special outlays on construction of this work, and for his rigid enforcement of the conditions set forth in the contract for securing that stability ; but how thoroughly rebuked his short-sighted, and, perhaps, factious censurers must have fell, when they discovered to their cost, by the des- truction, in 1855, of that most important work, that in all his care -and all his " harshness," Col. Alcorn was pursuing the course as a public servant, of courageous honesty and enlight- ened carefulness. The truth is, Col. Alcorn felt at the time, that his duty in the case of the Pass-levee was rather under- done than overdone ; and in conversation with Mr. M. B. Hewson, on the subject, frequently referred to the embarrass- ment in which he was placed in the case, by the absence of a sound and intelligent public opinion as to the conduct of those works. The purse-strings being in the hands of the tax-payers in the case of Levees, it is of importance to their best interests to place such measures as are necessary for the proper con- struction of those works, under the endorsement of their understandings. Having with this view referred to the special importance of such works as the Yazoo Pass-Levee, and the Old Town-Levee, &c., it is proposed, now, to offer some general remarks on Levee-foundations. EMBANKING LANDS FROM RIVER-FLOODS. 91 The more important portions of the system of m er-embank- ment in the case of the Mississippi, rests, as has been said, on foundations of puddle or quicksand. Continuing to dump in earth into embankments on such a foundation, is found in practice to result, after a greater or less waste of earth, in compressing the foundation downwards and outwards to a compactness sufficient for the resistance necessary to sustain the intended Levee. The Levee accordingly stands its height, crown, and side-slopes being in perfect accordance with the contract. This is all the public expect ; and unfortunately, with their present views, this is all they will sustain their Commissioner in enforcing. The flood, however, rises on the face of this Levee 10 feet, 15 feet, 20 feet even 25 feet, and a load of 600 Ibs., 900 Ibs., 1500 Ibs. becomes thus added to every square foot of the outer half of the Levee base ; while no corresponding weight on the inside is available for estab- lishing a counterpoise in the watery material of the foundation. The compression that the foundation underwent, originally, before the Levee attained the required height, was the result of the weight of the earth employed in its construction ; and it is only reasonable to infer that, with- the same foundation, a further load, whether of earth or of water, will occasion a fur- ther compression. Additional sinking, or " canting" under the outside slope, and additional bulging, or spreading of the inside slope, is a natural result under such circumstances j and the special weakening of foundation under the special saturation of a superincumbent head of water, combining with the other natural result in the case, no surprise ought to be felt that the great Levees, constructed after the general practice on the Mississippi, should be swept away before high floods. To con- struct those works properly, then, requires special steps in reference to the strength of their foundations. Brush makes a very good foundation in weak soils. McAdamized Roads have been carried through otherwise impassable marshes in England, 92 PRINCIPLES AXD PRACTICE OP on foundations of brush laid in considerable thickness upon the surface of the marsh. It is extensively used in Holland, and the "Low Countries," to strengthen the foundation of heavier embankments than are likely ever to occur in practice upon the Mississippi bottom. In Ireland, heavy embankments of the Grand Canal, and also, embankments of the Great West- ern Railroad have been carried in several instances across deep " flow-bogs" on brush. The Grand Trunk Railroad, of Canada, has a bank some thirty or forty feet high, across a deep and wide marsh, sustained by a brush foundation. Several such instances of the use of brush might be mentioned here, to show how useful for the purpose of Levee-foundations is a material that, along the banks of the Mississippi, may be obtained with- out stint or trouble. The branches of the trees cut off for the purpose, should be laid evenly across the base of the Levee, in layers 24 inches thick, the direction of those in each layer " ang- ling" across the line of the base, those of the layer next above being laid " angling" in the other direction. Two layers are quite sufficient for ordinary heights of bank, and ordinary weakness of foundation ; but in other cases, it were better to lay three layers' or even four. " Old beds," such as the Yazoo Pass, or Old Town Bayou, should in all cases be brushed with four lay- ers, compressible to a thickness of, at least, six feet, each layer having its branches laid across the line of Levee, askew the second layer crossing that of the first, and so, also, with the others. The brush should be cut off regularly, so that it would never extend on either side within ten or twelve feet of the toe of the bank ; pressed for even its own thickness into the foundation, and the brush covered up completely, the embank- ment resting upon it will not, necessarily, be open to the objection of leakage. Brushing, properly and carefully em- ployed, in even the highly unfavorable circumstances of the Key-works of the Levee-drainage, will constitue a perfectly stable foundation. Fascines are sometimes employed in the EMBANKING LANDS FEOM RIVER-FLOODS. 93 foundations of embankments ; but, while much more trouble- some, are not so efficient as simple brushing executed properly. Fascines may be described as small bundles of brush, each tied firmly like a birch-broom. These are laid down one row across the other for foundations of banks ; but all the advantages of their compactness may be secured in brushing, by selecting the brush carefully in the first instance long, straight, tough, and sufficiently light and in the next instance, pinning it down occasionally by wooden forks to the ground in the first case, and to the layer below it, in the next. More perfect continuity latterally and longitudinally may be obtained with the simple brush than with the fascines. Sand is another material most available along the Mississippi, for the purposes of artificial foundations. Loose in its parts as it is, sand is not supposed, generally, to be capable of constructing a mass of such stiffness as to distribute over its length and breadth the pressure of a heavy load. This, however, is the fact. Like water in other particulars, it is especially like water in dis- charging its pressures, under certain circumstances, latterally as well as vertically. This property of sand has lead to its employment in foundations as a substitute, in certain cases, for piles of wood and of iron. Wooden piles obtain their bear- ing mainly from the resistance presented to their section ; but sand-piles, in addition to this resistance, are found also to present a further resistance along their sides. Friction or adhesion, as it may be, this increased sustaining power of the sand-pile has been found highly useful in the preparation of foundations for heavy Engineering works in soft and deep alluvium. Where the base is not so weak as to require the use of piles, artificial foundations of ample strength are some- times obtained by spreading over the natural surface a thick and uniform coating of sand. In wet situations, however, hydraulic lime is sometimes added under this practice to the extent of one-seventh the bulk of the sand ; and as such an 94 PRINCIPLES AXD PRACTICE OF addition would, in all likelihood, be found necessary in the case of the great embankments of the Levee-system, the use of sand for artificial foundations for Levees, must, on the score of econ- omy, be confined to piling. Brush, however, is in all cases the best material available along the Mississippi, for the pre- paration of a Levee-base ; but before loading an unusually weak base with an unusually heavy embankment, it would be well, in addition to the brushing, to sink one row of sand-piles immediately under the intended site of the crown, and two other rows on each side of it, the piles in each row alternating regularly with those next it, thus : These piles ought to be about from 1 to 2 feet in diameter, the centre row being placed at intervals from centre to centre of say six feet, the next row on each side being parallel with this centre row at a distance from it from centre to centre of about 8 feet, the intervals between the piles of those second rows being from centre to centre 8 feet. The outside piles ought to be sunk at a distance from each other and from the adjoining rows of 10 feet from centre to centre. These piles may be put in by several methods. A light lift-ram being em- ployed to drive into the intended place (where the same may not be done by a heavy sledge) a wooden pile of the intended size, this pile, after being thus sunk to the required depth, must be withdrawn, and the hole filled in rapidly with sand for the purpose, this sand-filling being compressed at intervals as it EMBANKING LANDS FROM RIVER-FLOODS. 95 progresses, by blows of a rammer. By the time this sand pile is thus filled in and compressed, the driving-party will have been placed ready for work at an adjoining pile ; and thus the whole area will be piled, each pile being completed before the driving shall have been commenced for that adjoining it. Six or seven feet is quite sufficient as a depth for those sand-columns. The best method, however, for sinking those piles where the extent of the work would justify the outlay, would be by an iron cylinder, furnished on the inside with screw threads one-half the diameter in width ; for this might be sunk and raised without machinery ; and permitting conveniently of increased size, is well adapted to piling with sand columns of two feet in diameter. The larger and the closer the sand piles the more thoroughly do they pack the material of the base, and the more effectively do they increase their own bearing- strength. The regular mode for sand piling is that pointed out here ; but the rough mode of doing every thing in Leveeing will probably substitute, in sinking those piles, a pole forced into the ground by manual strength, and, in withdrawing it afterwards, worked around its point until the hole becomes sufficiently widened. The bottom of the pile, it must be recollected, will be very small under this proceeding ; but by ramming the sand thoroughly into the hole water or no water sand-piles will, under even such poor construction, assist largely in compressing the soft earth around them, and in supporting the load of a heavy em- bankment. Be the mode of construction for those piles then what it may, they are recommended in all cases of unusually heavy embankments and unusually weak earth ; and when even partially employed are highly valuable accessions to " brushing " in artificial foundations. The popular understanding must, how- ever, be satisfied in reference to every reform in the con- struction or management of Levees j and as the association of strength with a " foundation of sand " conflicts with all the previously formed views of that popular understanding, it is 96 PEINCIPLES AND PRACTICE OF well to sustain the use of sand-piles as has been done in the case of the recommendation of brushing by reference to specific practical tests. In reference to the general fact of sand being a strengthener of weak foundations, it may be ob- served that it has been employed successfully as such, under heavy masses of masonry at Geneva in Switzerland, at Bayonne and Paris in France, in India, in Surinam, and doubtless in many other places where its use has not fallen within the knowledge of the writer of this. In the " Annales des Fonts et Chausees ' ; the Reports of the Board of Public Works of France for 1835, a complete account of the use of sand in foundations is published ; and in order to satisfy the sceptical planter as to the utility of that material in foundations, the following extract is made from that report in the translation of a professional paper on the subject, by a member of the British Corps of Royal Engineers. " On a very soft soil nine piles about, 4 feet three inches long and 8 inches in diameter, and distant from centre to centre about 16 inches, were driven with a monkey weighing about 2 cwt. falling from a height of 3 feet 6 inches ; the driving was continued till the piles only yielded about 3 of an inch at a stroke ; upon these piles a load of 20,000 Ibs. was placed and the settlement amounted to about one-fifth of an inch. These nine piles were then drawn j and the holes in the soil filled in with sand ; 16 more piles were driven in the same way so as to occupy a space of 6 feet square ; the ground was then well rammed ; and a mass of masonry similar to that in tne former experiment was built and loaded with lead as before : Under a weight of 1050 Ibs. the settlement was 1-25 inch. " " 2100 Ibs. " " 2-25 inch. " 3150 Ibs. " " 3-25 inch. Which increased to 4-25 inch. Under a load of 18 tons the settlement was 1-5 inch. 21 tons made no sensible change, and 30 tons increased the settlement about 1-50, and after a month the total amounted to 3-5 inch. EMBANKING LANDS FROM RIVER-FLOODS. 97 A well about 12 feet deep filled up with silt and clay ; after having removed about 16 inches of soil from the surface the under stratum was found quite soft, a Ram penetrating 6 inches at a stroke. To harden this soil, 25 piles were driven about 4 feet 6 inches long each ; this forced the soil up about 16 inches above the previous level ; the driving was continued till 20 blows of a Ram weighing 2 cwt. let fall from a height of 3 feet only, caused a pile to penetrate about 4 inches, which took about 40 minutes' work. After having driven all the 25 piles and levelled their heads, they were loaded as follows : 12 tons caused a settlement of about 1-20 inch. 18 tons " " 1-10 inch. And in three days this increased to 1-5 inch. These piles were then drawn, and the holes filled with sand, which was well rammed, and which ramming caused a barrow full of earth to bulge up between the holes. On the ground thus prepared a mass of masonry was constructed and loaded with lead as before, and the settlement was as follows : 15 tons caused a settlement of 1-10 inch. 29 tons " " 2-5 inch. These weights were placed in April and remained on till De- cember, when the increased settlement amounted to f of an inch. The load being reduced to 10 tons, no further settlement took place between December and May." Other cases of the employment of sand-piles are given in the same reports ; but this is sufficiently specific and forcible to satisfy any reasonable doubt as to that employment in the foundation of Levees. Some of the cases given have been in situations where the silt and alluvium was over sixty feet in depth. Let the holes then be opened as they may, pack them well with sand as close to each other as the circumstances of the case may demand ; and the result will be, in all cases, an accession to the strength of the foundation, and, therefore, to the stability of the Levee. 7 98 PRINCIPLES AND PRACTICE OP Brush and sand combined will undoubtedly sustain the heaviest Levee under even the most unfavorable circumstances ; and the most available and cheapest materials for the purpose being thus sufficient for the requirements of any case, it is un- necessary to consider any other methods than those based on the use of these for accomplishing that important object in Leveeing, substantial foundations. The difficulty, however, of meeting every particular of im- proved construction in the Levee, lies in the sneer of the purse-holders in the case at what it calls " College" Leveeing. But the taxpayer who is enriched by the Levees of the Missis- sippi will make a grave mistake in assuming himself exempt from the hard lessons that have taught people placed under like circumstances in other countries, the wisdom of their pres- ent practice in water-embankments. In order to urge on the popular judgment of the valley the importance of the sugges- tions made above for fencing, grassing, and otherwise protecting the work, after its construction, for mucking, layer- ing, brushing, and even piling, in the course of its construction, it may be well to add here a few instances of the costliness and care involved in the case of European and Asiatic water-em- bankments. Touching the dimensions recommended above, it may be observed that Sir Cornelius Vermuyden gave the em- bankments of the Welland in England for a height of 8 feet, a base of 70 feet ; and that of the Ouse with a crown of ten f ee t_for a height of 8 feet, a base of 60 feet. The Ouse at Weisbach has for its embankment a height of 10 feet carried up on a base of 100 feet. Sir John McNeill, in the drainage of Lough Swilly in Ireland, gave his embankments a base of from 5J to 6 feet for every foot of their height. On the Lower Da- moodah in India, the " Bunds," as " Levees" are there termed, have a base for 4 feet high of 23 feet. In reference to the inequality recommended in the case of the dry and the wet elopes of Levees, it may be added that the practice of this EMBANKING LANDS FROM RIVER-FLOODS. 99 inequality is universal. Sir John McNeill a name distin- guished highly in his profession has given the Lough Swilly embankments, already referred to, an outside slope of from 3 to 1 to 4 to 1, while the inside slope is but 2 to 1. Sir John Rennie reports the construction of an embankment in connection with the Commissioners of the Nene Outfall, the dimensions of which were 5^ to 1 to seaward, 3 to 1 to landward, the top being 4 feet broad. Arthur Young, in his agricultural reports, mentions several cases of embanking, one of which he says was erected in 1800 : the dimensions were for the sea slope 4 to 1, land slope 2 to 1, 12 feet in height and 4 feet broad on top. The Dikes of Holland constructed principally as defences from the sea are generally raised 30 feet above the ordinary level of the country. Banks have been occasionally made twelve feet wide on top, and carried 2 feet above the high-watermark, they were in some positions turfed and strengthened in various places with stakes, or piles and planking. Sometimes banks were formed by driving rows of piles or stout stakes parallel to the river at distances of from 2 to 3 feet apart, and after uniting their heads by a plank, or weaving rods around them, the parallel spaces between were filled up with chalk or some other hard substance. Banks made of sand, in which twigs of brush-wood are placed horizontally and clayed properly with from 1 to 2 feet thick of clay, are found to stand remark- ably well. Coroboratory of the stress laid upon the selection of clay for Levees, it may be observed that in Holland, where the system of water-embankment is carried out under all the experience of centuries of disaster and destruction of life and property, and where the adoption of the best mode in each particular is a question of national concern, sand in the site of the Levee is rejected when better material cannot be obtained short of a haul of even Jive miles. In Europe, no trouble or cost is spared in the construction of water-banks to make them perfectly water-tight. Carrying up within the work a wall of 100 PRINCIPLES AND PRACTICE OP puddle, a practice which is known by every Engineer to be universal in the construction of all water-tight embankments, does not require for its endorsement an isolated instance like even that in the banks of the Swilly-drainage in the practice of Sir John McNeill. The care recommended in reference to the foundations of Levees is borne out by general usage in such works in England, in Ireland, in France, in Holland, in Ger- many, in India. The preservative measures urged above are but modifications based on universal practice. In England and in France water-banks are regularly " turfed ;" and in weak places protected with even stakes and piles. In Holland the water-banks are protected on the outside by a strong coating or matting of flaggers and reeds ; and on the inside are sus- tained by piles and planking, the slopes being coated thickly with grass. In the Swilly works, as illustrating the latest practice and highest experience in Europe, it may be remarked that the land-slopes of the embankments were all covered with turf; the water-slopes having been protected with a facing of fascines six feet thick at bottom and 4 feet thick at top, these fascines being laid in an oblique direction in the slope and fastened thereto firmly by forks of iron. Reason then has been first appealed to herein urging the adoption of the care recommended in the construction and protection of Levees; and these last references to the subject, show that the suggestions of reason in the premises, are fully endorsed by the general practice. But another point for viewing the subject may be illustrated by a reference to the cost of ILevee-maintenance. In Zealand the maintenance of their embankments 300 miles in length cost them annually $800,000 1 The maintenance of the embankments and the regulation of the water-levels in Holland, cost the enormous sum of $3,000,000 a year ! Sea-banks those works in both Zealand and Holland chiefly are ; but, on the other hand, it must be observed that in reference to the cost of their main- tenance they have been constructed with the best material in EMBANKING LANDS FROM EIVEE-FLOODS. 101 the best manner, and their preservation has been guarded since the time of their construction, with all available preservatives against decay. River-embankments, it is true, the Levees of the Mississippi are ; but it must be recollected that, until the management of one portion of those works by Col. Alcorn, very little care whatever had been taken in their construction, and equally little in their preservation. The maintenance tax then must continue a heavy burden for some time to come on pro- perty-holders within the Levee ; and this tax is subject to reduction in only the amount of care expended in constructing new Levees and in preserving both new and old. The method of construction and the means of protection after construction recommended above, are thus seen to be means adapted to reduction of taxation for Levee purposes on the parties chargeable with their maintenance. In this point of view then it is hoped the popular judgment will hesitate before it under- takes to sneer away recommendations so influential for public good as mere " College " nonsense. These remarks are intended not for the intelligence of the valley ; but for the guidance of that popular mind which may stand at the ballot-box, an impassable obstacle to even such a bold and talented reformer of the Levee- system as the distinguished gentleman to whom this volume is inscribed. 102 PRINCIPLES AND PRACTICE OF CHAPTER V. HIGH WATER MARK. THE municipal line is supposed, under the present law in Mississippi, to make each down-stream County higher than the flood that may inundate the County above it. Boliver is, therefore, assumed to have no concern in the drainage of Coa- homa. Engineering, then, must trim its practice to meet the absurd system of mere County jurisdictions. The wide revi- sion suggested hereafter, for the correction of flood-levels in Levee-surveys, cannot be carried out satisfactorily at present ; and hence does it become necessary to offer a few remarks on flood-levels in connection with the cramped working of the existing Levee-law. Simple as it may appear, the establish- ment of the High Water Mark along the lines of Levee, is very often a source of difficulty even to the skillful, and of error to the unskillful administrator of Levee Engineering. * And * Illustrative of the errors in construction resulting from want of skill in deter- mining High Water Mark, the following extract is made from the Report of 1856, by the then Commissioner of Levees, in Tunica Judge Hardeman: "The pro- file of Mr. Hewson's survey, &c. * * * * On being with him during the survey, and his taking the field notes of the same, it has been clearly indicated to me, that all the Levees heretofore built in the County, except that portion built and repaired the past season are from one to two feet too low, &c. These Levees should claim our first attention and, if possible, be repaired the coming season." Judge Harde- man might have even stated that the profile from which he speaks, showed some stretches of the embankments so much above High Water Mark as 5j feet ; while it EMBANKING LANDS FROM RIVER-FLOODS. 103 error, be it recollected, in this particular is the most dangerous that can happen in all the facts affecting the system. In the first place, it requires great caution in accepting testimony, generally more or less hazardous and loose, as conclusive. Checking the flood-levels above and below the point of diffi- culty in such a case, is the only means of passing from such conflicts of authority to fact. Nor in making such a compari- son must it be concluded that the rate of descent of flood-water is always that of uniformity. Across a bend it may be very rapid ; whereas, the line of flow crossed by a dense forest, thicket, or cane-brake, the flood-line, for a greater or less dis- tance up-stream, will be either that of exceptionally slow descent, or of even a dead-level. But further difficulties apply to the acceptance of local evidence as to High Water Mark. In Levees of wide fore-shore, it is a great, sometimes a danger- ous mistake to accept as absolute the High Water Mark cut on a tree on the spot, during the flood of 1844, or 1850, by even that oracle of flood-facts, an " Old Surveyor." The " Old Sur- veyor," doubtless, may have even made the mark at the exact height of the flood-water, then and there ; but this amounts to simply nothing, when it is recollected that the flood-water at the point in question was the flood-water of an outflow, and that the river-bottom, while having a fall of 7 or 8 inches per mile along its axis, has, across that axis, a fall of 5 or 6 inches per mile. The Old Surveyor, in short, forgot that, there being a fall in the outflow and also in the ground from the River-bank to his flood-naark, the damming back of that outflow would throw up the flood-level proportionally higher. This consider- showed other lengths, so much as eighteen inches below High Water Mark. The report made to him on the subject, holds in fact these words : " The old Levee, for 27 J miles, requires an average additional height of 1-55 feet, to bring it Aip to the required height of 3 feet above High Water; in some cases, this length of Levee was found to dip below the High Water-level each such dip involving, iu flood-time, certain destruction to considerable lengths of the work above and below it." 104 PRINCIPLES AND PRACTICE OF ation is highly necessary in ascertaining the true working High Water Mark. The ready-made Engineering of the first Levees if indeed, it be any thing more intelligent in some places to- day overlooked the fact that the flood-marks across the bot- tom follow the combined slope of ground and outflow ; and in consequence of this extraordinary error, many a mile of Levee has been swept away, many a dollar, in both scrip and cash, wasted. In practical illustration of the difficulties of fixing the High Water Mark a duty for which every man along the Mis- sissippi regards himself perfectly competent it may be observed here, that the High Water Mark taken, on all the local tests, at a point on the upper reach of " Old River," at Port Royal, in Coahoma County, Mississippi, was higher than the High Water Mark taken with like care, at a point half a mile down-stream, by so grave a difference as 4J feet ! Indeed, the evidence available in the case is so loose and uncertain a guide ; and an error in that guidance, involving the destruction of the Levee, it is highly important, in order to proceed under all the available lights with safety and confidence, that the selected levels of High Water Mark be compared one with another, along each whole drainage district ; and, finally, be revised by com- parison with the selected levels corresponding to them on the other side of the river. But this necessity supposes an improved system of Levee-law and Levee-administration. For the future, however, it is highly important that the public attention be directed to the wisdom of recording, as often as possible, along the river, the height of each year's flood. While the memories of parties living along the bank, on both sides, are fresh with marks of the late disastrous flood, a movement just now would be well timed for the commencement of such a system of record from end to end of the inundated shores. Well-ascertained evidence of this sort may be fixed at once, by the leveller; and after comparison and selection of all the facts, he may transfer the revised flood-heights to a series of EMBANKING LANDS FROM RIVEE-FLOODS. 105 .Bench Marks, sunk for the purpose, at intervals, inside the Levee. These Bench Marks should be driven down, firmly, three or four feet into the ground, so as to guard against their being broken or sunk ; and when their levels may have been duly ascertained, that of each in reference to its flood-level should be marked in red chalk or paint on one side, the num- ber of the Bench Mark being marked, likewise, (in order to identify it) on the other side. This use of Bench Mark-stakes is universal in the Engineering practice on the "Dikes" of Holland ; and like most of the usages established for the con- duct and maintenance of those works, is highly applicable in the case of the Mississippi embankments. 106 PRINCIPLES AND PRACTICE OP CHAPTER VI. LOCATION. The location of a line of Levee is a consideration involving permanence involving economy of construction and economy of maintenance. Large sums of money have been expended in Levees which, in several instances, have within twdve months of their construction fatten into the river. The cause of this has been ignorance or carelessness in determining the location. Private interest, however, is very often a disturbing influence in forcing the location of Levees from the line of safety and economy. A Planter has frequently been known to be so short- sighted as to have urged, and in fact obtained, the location of a Levee around three sides of even a " turnip patch" rather than consent to the necessity to himself as well as to the general publicof locating that Levee in continuance of its proper align- ment directly across that " turnip patch." * The increased cost * In the address explanatory of the causes of Levee failure during the late flood of the Mississippi, the Coahoma Commissioner, while putting the scientific conside- rations of the case in good popular terms, caps those considerations by reference to late practical experience ; on pages 17 and 18 he says : " Motion, whether of solids or fluids, naturally follows straight lines ; and all deviations from that law are accom- plished by an expenditure of impulse on the object occasioning that deviation. A sudden turn in a stream concentrates the whole energy of the fluid-motion on the one point, occasioning that sudden turn, hence the danger of all sudden turns in the Levee. In the original locations of the Levee all these laws of motion were violated ; no regard whatever was paid to the alignment; it was made to wind itself around EMBANKING LANDS PROM RIVER-FLOODS. 107 of constructing the embankment to meet this gentleman's nar- row-minded views, as compared with the cost of constructing the embankment on its proper alignment, has very often been ten times greater than the whole value of the additional piece of ground he had, by forcing the Levee out of its course, suc- ceeded in enclosing. This, however, is not the only injustice done under such circumstances to the body of the tax-payers ; for in making the Levee on the zig-zag necessary for the gentle- man's purposes, that course is subject to the additional injus- tice of either reconstructing the work on the proper ground when the zig-zag may have fallen into the river, or of -flooding the whole back-country when the shock of the high-water cur- rent striking against it directly, bursts its way in a " crevasse" through that zig-zag's up-stream juttings. The location of Levees, then, it may be seen from these remarks, should not be a mere matter of random ; but should be determined thought- fully with a view, in the first place, to the progress of the river whether in " caving" or " making," and with a view in the next place to the obviation of current-shocks. In locating a Levee, the first duty is the mapping out care- fully of the bank ; and, as far as may be done, by a careful sketching of the current-set, the "caving," and the "making." In the case of cavings and makings, every information as to their commencement, their rate of progress inwards, and their advance f/oww-stream, should be obtained carefully from local information and recorded at the proper points upon the map. The cavings and the makings of the bank pass down-stream in a series of waves, period after period ; and, therefore, by ascer- taining the rate of descent, the rate of penetration of a every cow-pen or horse-lot, presenting obtuso angles in the work at many critical points ; and that, too, without any increased strength of embankment at those points. At many such places the Levee during the late rise gave way, for the reason, as assigned, it was without strength to resist the current-shock." The most zealous and best informed friend of the Levee-system thus urges and endorses the importance of proper attention to the question of alignment. 108 PEINCIPLES AND PRACTICE OP " cave," or extension of a " make" at the point of its operation, the location of the Levee opposite that point may be made with a full knowledge of the conditions of its permanence. Levees built one year under such, evidently, necessary precau- tions, will not be swept into the river within either a few years or a few months after their construction. In order to illustrate this important point more fully, the method of mak- ing, and indeed of applying, the notes of " caving" and of " making" as recommended here, may be impressed upon the understanding of young Engineers more readily by a speciality. With this view then is given the following instances. The Chief Engineer of the Mississippi, Ouachita and Red River Railroad, having located the Eastern Terminus of that road at a point which failed to satisfy some of the stockholders, Mr. M. Butt Hewson, then directing the affairs of the Arkansas Midland Railroad, was engaged to report upon the question. The general grounds on which the original location had been based having been taken up by that gentleman as the heads of his inquiry, one of those so made the subject of his investiga- tion was the question of an anticipated change of course in the river by a " Cut-off," opposite Games' Landing. Mr. Hewson's report under this head presents the following illustrative remarks applicable to the considerations referred to here as guiding Levee-locations. " A long professional experience in the improvement of rivers, a somewhat intimate acquaintance with the laws of fluid-motion, and a few years observation as a resident on its banks, of the habits of the Mississippi, fail to place my answer to your fourth question within the limits of exact induction. It is much safer to speculate than to demonstrate on the subject of changes of the Mississippi River. I shall, however, furnish you with the facts bearing on your question ; and thereby enable you to judge for yourself as to the logical justice of my inferences. EMBANKING LANDS FROM RIVER-FLOODS. 109 " One general law of the Mississippi River subject like all general laws to special exceptions is very plain, viz : the progress of its cavings, like that of its currents, is down-stream. In that portion of the river under consideration, the set of the cur- rent from the Arkansas side struck the Eastern bank, some time ago, opposite the residence of Col. Martin ; whereas, now, the most Northerly thread of that current does not strike the same bank for several hundred yards lower down. So much for the general fact of the progression of the cause of active caving. I will now call your attention to the present stage of this pro- gression in the reach of river under consideration. Eleven hundred yards below Col. Martin's house, the present caving commences ; the Southern limits of this caving is not reached for a further distance of eight thousand one hundred yards still lower. The centre of this existing impact on the bank may, therefore, be deduced as midway between those limits of present caving that is to say, 4000 yards below the Northern limit of that caving. The force of a current, always a mini- mum at its outer limits, reaches its maximum in the middle of those limits. Now, the ' Cut-off' suggested, abuts on the bank at 3700 yards below the Northern edge of present caving ; and, therefore, the centre of impact, the point of greatest effect, having already, in its steady progress down-stream, passed below the site of the assumed ' Cut-off' for a distance of 300 yards, we may reasonably conclude that, so far as the supposition of this ' Cut-off' is concerned, the period of maxi- mum expectation of greatest likelihood is irrevocably passed. The beam that sustains the pressure of ten tons must be sup- posed perfectly safe from fracture under a like pressure of nine tons. In consideration of these general facts of the case, the inference is clearly opposed to the supposition of this ' Cut-off.' In order to examine the same question from another point of view, I will present an analysis of the evidence as to amount and rate of caving, furnished by gentlemen living 110 PRINCIPLES AND PRACTICE OP on the ground, at the several points along the line of this pro- gressing impact. Dr. Offutt states, that opposite his house (a point above Mr. Daniel's house) the bank has caved 400 yards in 20 years ; but at a less rapid rate for the last ten of these, than for the previous ten ; and for the last four of these latter ten, still more slowly. Mr. Wallace affirms that the bank at the same point, has caved 100 yards for the last 7 years ; and as compared with the gross average of these seven, ' very little' for the last 2 years. At this place the bank has caved : Within tho last 20 years, at the rate per year of 20 yards : Within the last 10 years, at a rate per year of less than 20 yards : Within the last 7 years, at the rate per year of 14$ yards : Within the last 2 years, at a rate per year of very littlo. " Here, then, is a constant diminution of the effect a dimi- nution in direct accordance with the passing away of the operating cause. Opposite Mr. Daniel's, (a point above the suggested ' Cut-off') the bank has, on the authority of Dr. Offutt, caved, in twenty years, five hundred yards ; the greater part within the last ten years, while the caving for the last year has been at a lower rate. Mr. Wallace's testimony as to this point, places the cavings at two hundred yards within the last seven years ; but for the last two years, very little. These eviden- ces stand thus : Within the last 20 years, at the rate per year of 25 yards : Within the last 10 years, over 25 yards : Within the last 7 years, 28 J yards : Within the last 2 years, much less. " In this increase of effect, up to a certain time, and diminu- tion of effect since that time, we obtain further evidence of the Southern movement of the centre of impact. Twenty years ago, it had not reached so low down as Daniel's ; and, conse- quently, did not then produce, at that point, its highest effect ; EMBANKING LANDS FROM RIVER-FLOODS. Ill but as it advanced, its progress is traced in the higher effect of the last ten years ; in the still higher effect of the last seven years ; and, as it passed further South, its continued progress in the diminished effect of the last two years. The point upon which the suggested ' Cut-off' abuts upon the bank has, accord- ing to Mr. Wallace, caved one hundred yards within the last seven years ; but for the last three years of these seven, at a lower rate : whereas, on the authority of the same gentleman, the bank, opposite Mr. Wilkerson's, (a point below the suggested ' Cut-off') having caved three hundred yards within the last 20 years, has maintained a higher rate of caving for the last ten. This point opposite Wilkerson's, coincides with the pre- sent centre of impact, as inducted above, from the existing limits of effect upon the bank ; and hence we may infer with logical propriety, that the energy (as evinced in the effects) has been increasing at that point for years ; and being, now, at its highest, must from this, forward, steadily diminish, until it shall have, ultimately, passed altogether away. Below Wilker- son's, the testimony of Messrs. Offutt, "Wallace, and Harris, shows an increasing energy in the increasing effect ; and, there- fore, as far as the irregularity of the outline, and the resistance of the soils will admit of a strictly exact result in such a case, demonstrating the present centre of effect to be below the ' Cut- off,' leads irresistibly to the inference that the time to speak of the suggested ' Cut-off' as within the limits of probability, has passed away. What the maximum impact failed to accom- plish cannot be expected from a minor impact ; nor is there any irregularity in the general outline of the bank to direct a special current against the debouch of the suggested ' Cut-off;' that outline, being in general a regular curve, may be held to receive, in the consequent uniformity of its resistance, an effect equally distributed. The rate of caving at the supposed ' Cut- off,' proves that the bank at that point is not inferior in cohe- sive strength, to that at any other point included in the 112 PRINCIPLES AND PRACTICE OF information obtained in the case. Besides, the result suggested must now, if it come at all, come from one side ; for the East- ern debouch of the ' Cut-off' has a making bank. If, then, the ' Cut-off' is to result from its present rate of caving, it will not, unless under some new and special combination of causes, occur for upwards of a century and a half. This supposes the centre of effect constant in its point of application ; but with the cen- tre traveling steadily to the Southward, the accomplishment of such a result must be deferred indefinitely. To sum up these remarks on the suggested ' Cut-off :' if the facts of the case do not positively establish that the ' Cut-off' will not be made, they go far to prove that such a supposition is eotirely improbable." The Report still further sketches out the method of reason- ing, from the observed facts of " Making," and " Caving," in the following consideration of the question of increased shoal- ing at Games' Landing : " To meet your fourth question broadly, I must consider what other changes, as the supposition of the Cut-off must clearly be rejected, is most likely to take place in the River between Ferguson's Point and Games' Landing. The align- ment of the River above the Railroad Terminus shows, as detailed above, a change of course, in a distance of three and a half-miles, of ninety degrees : in other words, the Mississippi River, curving from a point about three-quarters of a mile above the Railroad Terminus until it fronts the house of Mr. W. C. Campbell a distance of three and a half miles turns fully one-quarter round. To divert the whole volume of the Mississippi River so far from its direct course, implies the ex- penditure by the River of an immense energy on the resist- ance causing this divergence ; and hence may we understand, in a general way, the amount of the force employed in opera- ting on the bank between Mr. Campbell's plantation and the site of the Railroad Terminus. The caving consequent on the EMBANKING LAND'S FROM RIVER-FLOODS. 113 force so exerted against the bank between those points, stands at present in its progress to the southward, as follows : It begins at a point 500 yards below Mr. Campbell's ; and extend- ing clown the River-bank to the head of Island No. 80, a point 1200 yards below the Railroad depot, the centre of impact (the point of greatest effect) being at the present time situated, therefore, upwards of 2700 yards higher up-stream than the Railroad Terminus. The rate of effect at points along this bank I am unable to say ; but the maximum effect having yet to operate over a space of 2700 yards before it shall have reached the Terminus, has yet, in obedience to an infallible law of the River, to come sweeping down with all its powers of change and destruction on what remains of Ferguson's Point. In the march down-stream of the axis of current lies the cause of any such change of channel as may be looked for between the Railroad Terminus and G-aines' Landing. When the cur- rent of the River first swept the Northern bank of Ferguson's Point, the Southern bank of that point lay at the head of a line of slack-water. Island 80 resulted from this ; for the matter that passes off in suspension under the impulse of a current of 4 or 5 miles an hour, will be precipitated in currents of one or two miles an hour. Now, however, Ferguson's Point has been to a considerable extent carried away, within the last six years, to an extent, according to Col. B. Gaines and Mr. Reinhart, of eighty yards ; and as a consequence, the Island formed under the shelter of that Point begins now to receive the shock of the river current." Observations and applica- tions of the above description being employed as a guide in the case of the location of Levees, the determination of those locations may be made with a proper regard to the most important considerations affecting their permanence. All points of the bank being thus examined under the light of the circumstances affecting their permanence, the limits of per- manence inferred therefrom, must be noted at intervals on the 114 PRINCIPLES AND PRACTICE OP plan ; and the alignment of the Levee being made to conform to .the considerations proper to itself, the location must be laid down on the plan within the restrictions of these limits oi permanence. The laws governing the alignment of water- embankments, like those governing the alignment of Railroad tracks, point in the first instance to straight lines. The course of motion, whether of solids or fluids, is naturally rectilineal. As has been observed in the latter of the two foregoing ex- tracts from the report of Mr. Hewson, the diversion of motion from its original line to any other line, involves the expendi- ture of more or less mechanical effect. In diverting a surface layer of the Mississippi flood- water that mass moving at the rate of some 6 miles an hour from one course to another, it can be readily understood that the expenditure of mechanical effect is very great. In order, then, to discharge this unavoid- able force with the least possible danger to the Levee, it should (so that it be distributed equally over a large space) be dis- charged invariably over a curve. These few simple principles point out clearly the rules governing Levee alignment straight lines where such are practicable, and regular curves where they are not. Laying down this curvilinear rectilinear alignment in a manner as far as possible to accord with the general lines of the river-currents, the Levee will be exposed at all its points to the least possible shocks and washes. The limits of permanence laid down on the plan according to the considerations premised above, the lines of current controling the general direction of the alignment, that alignment making all its changes of direction over regular curves may be laid down finally on the plan with the fullest faith in it as the loca- tion of greatest safety and greatest economy. Often, however, it will occur in reasoning on the considerations guiding in lay- ing down the Levee-route on the plan, that two or more routes may appear to possess equal merits. Laying down all these routes on the map, each must be made a subject of instrumen- EMBANKING LANDS FROM RIVER-FLOODS. 115 tation and estimation ; and always taking into consideration that the closer the alignment adheres to the limits of perma- nence the greater the amount of good to the public, the relative cost of the respective routes determining, finally, as to the one for adoption. So much then for the general considerations affecting location. Special considerations in reference to stretches of considerably heavy embankment, may apply such, for instance, as ridges furnishing, witliin the limits of permanence, an economical location for the Leveeing of a neck of swamp. These must in all such cases be examined carefully first by the reconnoisance of a professional eye, and next, if found necessary, by instrumentation and estimation. So much then for the considerations applicable to location under the cramped action of the Mississippi Levee-laws. 116 PKINCIPLES AND PRACTICE OP CHAPTER VII. SURVEYS . HIGH Water Mark, it has been shown, cannot be obtained so readily as is supposed by the populace. On the contrary, the correct determination of the flood-line for fixing the height of a Levee, is a duty that involves, not only sound judgment and patient investigation ; but also careful and extensive instru- mentation. The location of a Levee, it has also been pointed out, is something more than a matter of off-hand expediency. This duty of the Levee-system is at present like the determi- nation of the flood-line assumed popularly to be fully within the knowledge and capacity of every man living on the banks of the river. The considerations affecting the discharge of such a task have, however, been shown already to be too in- tricate, too extensive, too delicate, to be grouped and combined into correct results by even men of fair standing amongst the members of the profession as Field Engineers. Location, with the commonest pretensions to care and science, requires, as has been indicated in the remarks on that head, as a first necessity, a full careful survey, an exact and special map. The first duty then of an improved system of Leveeing should be the prepar- ation of maps and profiles the surveys for those maps and profiles to be extended from end to end of those sections of country referred to hereafter as Drainage Districts. These surveys can be directed only by a mind quick in observation EMBANKING LANDS FROM RIVER-FLOODS. 117 and ingenious in inference this quickness and ingenuity guided by a familiarity with fluid-motion and river phenomena. They should show by actual offset-chaining the line of bank ; and by careful sketching, all " makes," " bars," and currents. These instrumentations should bring out all the facts of cavings, so as to furnish to the mapper the penetration, progress, and stage of each cave. All facts of possible or probable influence on the objects of the survey such for instance as the facts of Moon Lake in Mississippi, of Old Town Lake in Arkansas, of Bayou Atchafalya in Louisiana, their position, form, level, flow, &c. &c -ought to be carefully ascertained and connected with the great body of the facts of the District survey. Every foot of survey, whether of experimental lines along ridges, across swamps, or any where else, within a Drainage District, should be laid down regularly when completed and connected with the general survey on the plans and profiles of that Dis- trict. These plans should consist of two sets ; one set on a scale as large as practicable for a map of convenient size, showing the ground along the whole front of its whole District. Divided into squares by light lines across its face, this map should be made an index map by numbers set on each square so shown, to the several sheets of the second set of maps a set made to a sufficiently large scale to embody all the minutiae necessary for practical purposes. These enlarged working- plans, amongst the other particulars referred to as guides in location, should show the site and title of all survey-stations, the site and number of all Bench Marks, the elevations of the Bench Marks recorded duly by transfer from the District pro- file. The first exact and minute survey of a Drainage District effected by a special staff, the constant staff required for the Engineering direction of the District-works, should spend all the spare time from construction-duties, in keeping up, by survey, connected records, on the working plans, of all changes of " bars," increases of " makes," shiftings of currents, penetrations and pro- 118 PRINCIPLES AND PRACTICE OF gressions of " caves." These facts ascertained and laid down on the plans, year after year, the continuity of the records on the whole river will, after a time, enable a Levee-administration to reduce to something like scientific exactness, every consid- eration affecting the perfect practical efficiency of their most important duties. The maps described here have been deduced as necessities of location from the circumstances affecting it on but one side of the river. But it has already been shadowed out in the remark on that subject, that the location of a work on either side cannot be made with complete care without the exact com- parison with the location on the side opposite. The practical difficulties referred to, under the head of High Water Mark, also suggest the comparison of levels on one side of the river, with levels on the other side. But the necessity arising from these considerations is indicated still more forcibly from another point of view. The remarks offered on location show the necessity of avoiding all causes of excessive pressures, or shocks upon river-embankments. The currents treated with disregard, and the lines of least resistance duly observed, in location of a Levee, the conditions of location in reference to shocks are fully met, so far as the considerations affecting them on that particular side of the river. But let it be assumed that . the Levees up-stream have, on both sides of the river, a consid- erable breadth of fore-shore ; while at the point of this locally judicious location, the Levee on both sides happen to have for their fore-shore, each but a narrow strip. The width from Levee to Levee, across the river, may thus happen, up-stream, to be large, while below at the point of the locally good loca- tion the width across the river from Levee to Levee may happen to be comparatively narrow. This sudden contraction of the flood-flow will throw an increased shock of current on the Levees at the point of that contraction ; and thus does the location of a Levee on one side, without due regard to that EMBANKING LANDS FROM EIVER-FLOODS. 119 of the Levee on the other side, involve some of those avoidable contingencies of breaching the embankments which judicious location undertakes to guard against. Proper location, then, notwithstanding conformity with all considerations of " cave," current, and alignment, on one side of the river, cannot be made without comparing the location based on all these, with the location on the other side. The narrowest width of the river- flow, in the natural state, is said, in the late able pamphlet of Col. Alcorn, to be opposite Randolph, in Tennessee. A bluff at one side and a high bank on the other side, it appears that at that place the floods of the Mississippi pass off, without any particular increase of current, or wear of the bank, within a width of 2,000 yards. A proper survey of the river might pro- bably throw further and more correct light on this particular fact ; but whether Randolph be, or be not the site, and, whether 2,000 yards be, or be not the width, of the narrowest natural channel of flood-water, some site and some width answering those conditions ought to be ascertained for fixing the ruling width of water-way between the lines of river-embank- ment. This ruling width determined in reference to the width, section, and current of several " narrows" in the flood- flow, the proper location of Levees on either side of the river, requiring that the flood-width be never lower than the stand- ard, such a location on one side can be made only pari-passu with the corresponding location on the other side. An inter-littoral survey is seen thus to be a necessity of economic and perma- nent location. This survey connecting District surveys across the river, does not require absolutely to be one of detail. In- termediate Islands should certainly be embraced in it ; but in consideration of the cost of such an extension of labor, it is, perhaps, better (for some time at least) to omit soundings. A skeleton Trigonometrical survey, then, connecting stations in local surveys on both shores, and on intervening islands, is all that is absolutely necessary in addition to the surveys already 120 PRINCIPLES AND PRACTICE OP described for completing the enquiries and records necessary to a perfectly correct and economic system of Levee-adminis- tration. The triangulation necessary for this survey, should be carried out with a view to fixing each station under the endorsement of one or more checks ; but due regard to be paid, in all cases, to the regularity of the shape of the triangles, and to the including in each station-book on the field, of each of the stations that may be possibly combined in any one triangle. The correction of bases, the adjustment, in estima- tion, of spherical excess, &c., are details that, in addition to all the care suggested for the field, are highly necessary in carry- ing a base line of some 2000 or 3000 yards, with all the correc- tions of even several intermediate checks, through a series of some eight or ten hundred triangles. The triangulation, however, " poled out," the angles taken, the base measured, and the calculations made, the, District-surveys may be carried out in detail as described, connecting regularly with the stations of the triangulation. The diagram of the trigonomet- rical points having been laid down, the filling in of- this diagram, on each side, with the details of each local survey, will not only guarantee an accuracy otherwise unobtainable in that local survey, but will also present a perfect connection of the facts on both sides of the river. This connecting survey will, in the first place, by doubling the data, lead to reliable infer- ences in all cases as to the height of High Water Mark will, by embracing in exact detail the facts of all the " narrows," limiting the width of flood-flow, lead to correct deductions as to the " ruling" width proper in the case of opposite Levees ; and by representing the relative position of Levee-alignment on each side of the stream, point to those modifications or changes of site that may be necessary for conformity with the conditions of efficiency and permanence. EMBANKING LANDS PROM RIVER-FLOODS. 121 CHAPTER VIII. ADMINISTRATION. * The subjects of flood-line, location and survey involve neces- sities at evident conflict with the present system of Levee- legislation. In Arkansas and in Louisiana the administration of the drainage-interests are in the charge of the State ; in Mis- sissippi, in Tennessee, and in Missouri, the charge of those interests is parcelled out among the River-counties. In all these * The opinions put forth here are found to be strikingly coincident with those of the Chief Commissioner of the Levees of Mississippi. His Eeport for 1856, to the Legislature of that State, has just been brought under the notice of the writer of this, and presents an opportunity for tho endorsement of the views given under the above head, as in the following extract from that Report by so well- informed and judicious an observer : " The practical results of the law placing the direction of the Levee within the respective limits of each County on the river, in tho hands of a Board constituted on the principle of local representation, have been, so far as those results have fallen under my observation, decidedly unfavorable to the law. The act substituting a sin- gle Commissioner for these Boards of Commissioners in Tunica and Coahoma, has worked, in my opinion, much more advantageously to the interests of the Levee. " This individual management is, in truth, in more close conformity with the phy- sical principle that should direct legislation in this great practical work. No mere municipal line can divide an interest which is declared one and indivisible by the eternal law that rolls out the floods of the Mississippi in an unbroken whole. In not only principle, but also in practice, do I find reason to recommend this system of individual control in the design and construction of our Levee. It went into operation in the County of Coahoma two years ago, receiving from the previous re- 122 PRINCIPLES AND PRACTICE OF cases the legislation is injudicious in its working in Arkansas and Louisiana less so, however, than in Tennessee, Missouri, and Mississippi. The latter States presenting the extreme form of objection to non-conformity of Levee-la w with Levee-require- ment, the following remarks on points of this non-conformity are confined to the legislation of those States. The experience that has lead to the preparation of these remarks, has been acquired in Arkansas, and in Mississippi ; and as the latter is one of the gime, the legacy of a wasted resource, an exhausted treasury, an unsettled indebt- edness, an imperfect record, an insufficient and incomplete Levee, and last, but worst of all, an almost total wreck of public confidence in any municipal adminis- tration. But what now, in two short years, is the condition of those affairs 1 Though I discuss a principle only in this case, it is not for me to answer, nor is my answer necessary when the answer has been already given in general terms by the County. This principle of individual management in carrying out our Levee has, in a direct issue with the principle of divided management, been endorsed emphatically by the intelligent people of Coahoma. Aware that the unity of the Levee could not be broken by municipal divisions, I had the honor to bring forward, two years ago, the existing law, giving a general jurisdiction over the Levee to the ' Superior Board of Levee Commissioners.' The working results of this law have fallen short of the physical principle which was sought to be reached by it. The interest of the river Counties is in truth such a perfect unit in reference to the Levee, more or less diffi- culty will always be found in carrying out so absolute a unity, under even the strongest organization of independent jurisdiction. A breach in the Levee at the upper end of Issaquena County, would, in the event of overflow through that breach, cause the destruction of property in the County of Washington by back-water. An overflow through the Levee at the lower line of Bolivar County, while it may do very lit- tle damage in Bolivar, may spread out one great sheet over the length and breadth of Washington County. In Tunica, an active caving of the river bank has already ad- vanced within some fifty yards of the Levee, and still advancing, the next flood in the Mississippi will, in all probability, break in an immense volume into Eagle Lake. Now, to the greater portion of the people of Tunica, this result is a matter of com- parative indifference whereas the outfall from Eagle Lake, being Southwardly and Westwardly, such a result will spread devastation far and wide in Coahoma ; so the construction of the Levee in the Southern border of De Soto, is a matter to the peo- ple of that County of comparative indifference the majority interest is already pro- vided for the Levee is left open, and the country South of them becomes the suf- ferer. The local administration is the supreme power over that portion of the river EMBANKING LANDS FEOM RIVER-FLOODS. 123 States whose Levee-legislation illustrates its conflict with Levee-expediences most forcibly, it is therefore selected here to illustrate that fact by examples mainly special to itself. The conclusions, however, though drawn to some extent for special instances, are general in their application to those States where Levee-administration is distended to the extent of a whole State, and also to those where it is narrowed' down to the limits of a County. Drainage-legislation is based on error in limiting the admin- within the limits of De Soto. Tunica has not the protection of a representation of the common interest which is bound up in the Levee an indivisible unit. Again, the Leveeing of those heads of Sunflower which traverse Lewis' Swamp, in tho County of Coahoma, is a work of secondary concern to the great majority of the peo- ple of that County, but though situated within a jurisdiction regarding it with com- parative indifference, this part of the Levee is of much deeper importance to the upper portion of Bolivar, than any like distance of low bank on her own front. While Coahoma required outlays at other points of much more urgency to her safe- ty, her resources have naturally been employed at those points to the consequent injury of an immense amount of property in a neighboring jurisdiction. " Indeed, such has been the interest felt in Bolivar in regard to this Levee, that influential citizens of that County, had offered, in addition to the only resources which Coahoma could agree to apply to that purpose, to pay a large bonus to any contractors, who would bind themselves in a contract with Coahoma, to Levee Lewis' Swamp. But, if a flood shall have risen before this swamp is Leveed, undei the present state of affairs, how bitterly will the people of Bolivar regret, that whilo the local interests in tho Levee have been provided for by an authority and an ad- ministration, there is no head, no strong individuality of general management, to represent the strong individuality of general interest. Wise legislation on practical improvements must always conform to physical laws. A general controlling authority is necessary also in this point of view, to represent the great and wide considerations involved in the intelligent design, and the straightforward independence, required in the faithful execution of that design, from end to end of that great physical unit, the Levee of the Mississippi and Yazoo bottom. From the commencement of the system, I have sought to convince the Levee interest of the necessity of this individ- uality ; thus far my efforts have been unavailing. The plan of operation is one that I have never approved. I have been driven to its support for the reason, that no other plan could be suggested which could command the united support of the in- terests involved." 124 PRINCIPLES AND PRACTICE OP istration under it by arbitrary lines. In Shelby County, Ten- nessee, the proper administration of the Levees is not placed under the guarantee of any considerable interest. Some eight or ten thousand acres of swamp subject to the overflows of Nonconnah Creek and Horn Lake must always constitute an insufficient interest for the enforcement of an independent administrator of the Drainage-works of that area in the con- struction, protection, and maintenance of the Levees under his control Levees extending to a length of some 15 miles. In- deed a question presents itself this moment as to whether, within the section referred to, there exists a single plantation, there resides permanently even a solitary squatter. The fact is, the Leveeing of the tract in question cannot, in all likeli- hood, be said under existing legislation to be the business of any one ; but even if it be the business of any one, the area to be enclosed does not present, in all probability, the ways and means for raising does not in short present a sufficient induce- ment to justify the considerable expenditure required for its embankment a sum that cannot be less than some $30,000. And yet, if this part of the bottom be left unenclosed, the whole Levee from the Tennessee line to the Yazoo, can be saved from utter uselessness for the drainage of the Valley but by a special work pressing on the limited resources of the Levee-interesis in De Soto ! If a physical facility have not brought this special em- bankment within the limits of the ability of De Soto, the inun- dations from Horn Lake will ignore the hampe rings of Ten- nessee and Mississippi legislation by forcing combined action of all the counties between the Nonconnah and the Yazoo, in the construction, protection, and maintenance, of either a general Levee from the Tennessee line to the Nonconnah hills, or of a special embankment in De Soto County from the existing River-Levee to the Coldwater high lands. But instances of the bad adaptation of the present law are numerous. In Tunica County, Mississippi, the Commissioner is charged with several EMBANKING LANDS FEOM RIVER-FLOODS. 125 Keys of the drainage of Coahoma, Sunflower, Tallahatchee that at Buck Island Bayou, that at Couple-Timber Bayou &c. These, however, it may be said are Keys also to the Drainage of Tunica itself ; and, therefore, are their safe-keeping placed in the hands of the local Commissioners under some guarantee. Tunica, however, is charged with another Key to the Drainage of Coahoma, Sunflower, and Tallahatchee the Levee immedi- ately covering the plantations on the North shore of Moon Lake. This latter Levee protects little or none of the settlements in Tunica ; whereas the flood-water rushing through a crevasse therein sweeping southwardly across Moon Lake and the Yazoo, will inundate the fields and homesteads of Tallahatchee, Sun- flower, and Coahoma. Want'of interest in its construction, want of funds to pay for that construction, demands on their treasury and attention at points of concern to themselves, may lead the people of Tunica at any moment to regard this Key to the Drainage of Coahoma and its adjoining counties, with a very natural, and indeed quite excusable neglect. The most vital interests, then, of Coahoma, Sunflower, and Tallahatchee, are placed, by the system of County-jurisdiction in Leveeing, beyond the control of these counties placed in the hands of parties who can afford without loss, to regard the protection of those interests with indifference. A tax to be collected from them- selves for the construction or repair of the Levee covering Moon Lake protecting Coahoma would, naturally enough, be not carried probably without some effort amongst the people of Tunica. But the lower Counties show the working of the system of local-jurisdiction in still more objectionable lights. In Coahoma County there may be said to be no settlement south of Lewis' Swamp. The Coahoma people, as a body, care very little therefore, about the Leveeing of Lewis' Swamp ; whereas, the floods breaking through that swamp, may at any time after the failure of its Levee, inundate at even ordinary floods, the lands and homes of Bolivar and Sunflower, unless 126 PRINCIPLES AND PRACTICE OP Levee-jurisdiction be regulated by some limits more practical in their operation than those of arbitrary lines. The hampered workings of Levee-legislation are thus seen by a few illustra- tions to be unjust and unsafe for the whole Valley of the Yazoo for De Soto, for Tunica, for Coahoma, for Bolivar, for Sunflower, for Tallahatchee, and (the contingencies of local indifference, local urgencies, and local taxation, accumulating unfavorably as the testing of this legislation is carried down-stream) the injus- tice and unsafety is still greater in Washington than in Bolivar ; and as compared with Washington is still greater in Issaquena. But what is the remedy for the evils of the present system of Levee-government? An extension of Levee-jurisdiction according to certain physical proprieties. Working necessities point clearly to the removal of the existing limits on the ad- ministration, in the State of Mississippi, of river embank- ments. The location considerations referred to above, operate in full force, whether or not the ground lie one-half in Wash- ington, the other half in Issaquena. In locations so circum- stanced the surveys to be made must be common to both counties. The flood-level too, is a subject of inquiry that, as shown above, cannot be cut short by a mere legislative fiction j and, here, again, is another point in which the practical duties of Levee- administration ignore the system of imaginary limits to Levee- jurisdiction. Other considerations point still more forcibly to the necessity of seeking some new boundaries for the limita- tions proper to that jurisdiction. Bolivar's voice and Sunflow- er's voice in the appointment of the Commissioner directing the Levees of Coahoma, will guarantee the construction, protection, and maintenance, of a Levee across Lewis' Swamp, quite as soon and quite as surely, as that across the Yazoo Pass, or at any other point in Coahoma. So also as between Coahoma and Tunica : * give Coahoma, Tallahatchee, Sun- * The joint interest of conterminous counties in the proper administration of their respective Levees and in the making and skill of their respective surveys, is EMBANKING LANDS FKOM EIVER-FLOODS. 127 flower, votes in the election of the administrator of Levees in Tunica ; and Coahoma, Tallahatchee, Sunflower, will assuredly be thereafter saved from the dangers, the, perhaps, ruinous in- difference that, under the present law, may at any moment inundate their hearths and fields by overflows discharged upon them in desolating volumes through Moon Lake. But what distribution of jurisdiction will conform best to the practical and social considerations entering into Levee-administration? From Cape Girardeau in Missouri, where the highlands abut upon the river, to the mouth of the St. Francis in Arkansas, where the back-drainage of the intervening country must be discharged, defines a Levee-district, which, bound together by a community of interest, is for all the purposes of proper Levee-administration, ,an absolute unity. From Sterling in Arkansas, at the mouth of the St. Francis, where the Levee rests on the slopes of Crowley's Ridge, to the mouth of White River, where the back-drainage of the intervening country discharges, is also, so far as the Mississippi Levees are concern- ed, a unit in Levee-interest ; and, therefore, should be a unit pointed out by inference in the following remarks of Judge Hardeman, as Levee- Commissioner to Tunica County : " The object of making this survey was, with the then indication of the active caving of the bank of the River at the Southern part of Trotter's Field, to ascertain whether for the protection of the back-country, we would be compelled to Levee around Eagle Lake. * * * The indication of cave, &c., which may save this county and Coahoma a considerable amount of money, &c. The question, however, as to whether we go around Eagle Lake ought to be deter- mined by concert of action between the Levee Commissioners of Tunica and Coahoma, as they may decide as to the best interests of the two counties ; for, as before remarked, there is a common interest of the two counties in erecting a Levee across the Pass, &c." Report for 1856, page 5. This extract specifies an instance in which the location of a Levee in one Levee-jurisdiction is held to involve a loss or a gain of a " considerable amount" of money to the tax-payers of another Levee-jurisdiction ; and specifies also an instance in which the construction of a Levee within one jurisdiction is considered to be a question of drainage within another jurisdiction. And the parties thus concerned, in the one case in their pockets and in the other case in their property, to be deprived of all influence in uiak'no- ^mt location, or in expediting that construction. 128 PRINCIPLES AND PRACTICE OP in Levee-administration. From Pine Bluff, the nearest escarp- ment to the Mississippi of the Arkansas Uplands, to the mouth of Eed River in Louisiana the outlet of the rain-shed of the intervening bottom lands the community of interest in the inclosing Levee is so indissoluble that the proper administration of that Levee over-riding all imaginary boundaries whether of County or of State must, in furtherance of sound policy and capable management, be centered of necessity in one and the same intelligence. On the Eastern bank it has already been indicated sufficiently plainly, that the Levee-interests from the base of the hills below Memphis in Tennessee to the mouth of the Yazoo River the debouch-channel of the back-drainage of the included area is so thoroughly identical in its drainage affairs socially and practically that the administration of those affairs within that area has been described by Col. Alcorn, most correctly, as " one and indivisible." The natural the social and the working definitions of the remaining jurisdic- tions in Louisiana and in Mississippi, may, with the views presented above, be determined by those acquainted with the physics of those sections ; and so also of the jurisdic- tions in Tennessee, Missouri and Illinois. The limits as- signed the districts defined here are, it ought to be observed, those on their Mississippi front, the limits on their inland side, in each case being located as hereafter indicated on such lines as may be necessary for the equal dis- tribution of Levee taxation. Sufficient, however, has been said here to show that physical considerations applied socially and practically, while ignoring the existing limits to Levee-ad- ministration, describe plainly certain limits demanded for its efficiency. * * Some four years ago the grounds taken here were taken by Col. Alcorn, see note to page 121, in urging the consolidation of Levee-government in his Report as chairman of the Superior Board of Levee-Commissioners, to the then Legislature of Mississippi. The essential unity of Levee-management was suggested subsequently EMBANKING LANDS FROM KIVER-FLOODS. 129 Unity of interest can be served truly by only administrative unity. Each Drainage District then (as the united areas referred to above may be termed,) ought to be placed under a single administrator. One Commissioner should be charged with the direction of drainage embankments from Cape Girardeau to the mouth of the St. Francis ; one from the mouth of the St. Francis to that of Arkansas River j another from Pine Bluff to the mouth of Red River. On the opposite side a single Commis- sioner should be charged with the control of the Levee-interests from the Nonconnah to the debouch of the Yazoo. But while the social and the practical considerations in the case conspire by Judge Hardeman, Levee-Commissioner of Tunica in his report for 1856, to his fellow commissioners, Messrs. E. B. Bridges and J. A. Cole, in the following judicious re- marks : " The propriety of this repeal may be a question of doubtful policy, as it must be apparent to you that a common interest in the Levees fronting all the counties on the Mississippi River from Horn Lake to the mouth of Tazoo River ought to be ap- preciated by all land-holders within that Delta formed by Coldwater, Tallahatchee, and Yazoo Rivers, to its entrance with the Mississippi, a distance of 350 miles, em- bracing a part of the County of De Soto, all of Tunica, Coahoma, Bolivar, Washing- ton, Issaquena, Sunflower, and part of the counties of Warren, Yazoo, Tallahatchee, and Pauola. * * * Tunica County tax-payers on lands bordering on Cold- water, are as much interested in the Leveeing around Horn Lake; De Soto County, as they are in the Levee of their own County fronting the Mississippi River ; also tho land- owners bordering on the Mississippi River and Coldwater are equally inter- ested in Leveeing the Yazoo Pass in Coahoma, as the water in making its way through the Pass backs up through Moon Lake, &c., to the town of Austin and its vicin- ity. The question may be well asked : can this common interest in the Levees on the river be carried on without concert of action, $c." Messrs. Hardeman, Bridges, and Cole, arc gentlemen of intelligence, of practical acquaintance with the working of the Levee system ; and, as such, their testimony to the fact of Levee-unity, so far as it goes, is highly valuable. The remarks in the above extract point to the restoration of the Superior Board of Commissioners as fulfilling all the suggestions of Levee-concert ; but, loose and scattered in its parts, the action of that Board has already been found to be utterly inefficient. Some other form of government, therefore, must be in- stituted to meet the universally accepted fact of Levee-unity ; and the form of a gen- oral Board having been tried and found wanting, the necessities of the moment point to the only practical indeed the only untried form remaining, that of admin- istrative individuality. 130 PRINCIPLES AND PRACTICE OP to define the working limits of District Levee-jurisdictions, the practical considerations point to a conclusion still in advance of existing systems. The working expediences involved in capable administration of Levee-drainage are not confined to one side of the Mississippi. The comparison of High Water data obtainable on the East bank with that obtainable on the West bank, has been referred to as an expediency in determining the question of High Water Mark. This comparison, then, indicates the ex- tension of District-administration to an administration of wider scope and more general duties. The necessity of full know- ledge of the location-facts on the opposite side, and of certain accord between the locations on both sides, is another instance under a system of District-management of a commingling that leads plainly to a further widening of administrative commu- nity. A fusion of District units is an expediency on these grounds ; and therefore, on the further ground that, only by such a fusion can the Levee-interest of the great Valley of the Mississippi receive the first great contribution, the prime essential, of a broad, capable administration a full, correct and connected set of working maps. The scientific and practical conditions of the drainage of the Valley by Levees require, therefore, that the administration of each Drainage District to the full extent of its natural limits, be placed in the hands of an individual Commissioner ; and further require that the admin- istration of all joint-duties of the Drainage Districts on both sides of the river, be placed in the hands of those individual Commissioners assembled in general Board or Council. Legis- lation based on the system of administration sketched out here, is clearly the only one adapted to the direction of those important works under the lights of scientific principle, of practical forethought, of sound economy. Great difficulties, however, obstruct the effective working of proper machinery for the managemer t of Mississippi Levees. The popular intelligence holding the purse-strings of the system EMBANKING LANDS FROM RIVER-FLOODS. 131 does not, in some cases, go to the extent of recognizing in Leveeing, any skill beyond that of its own crude observation. It sometimes commits the mistake of ignoring the existence of centres of special knowledge, whether in Medicine or in Engi- neering. Col. Alcorn has been constantly hampered in his Commission by this condition of public opinion. " Such," he says, in his last pamphlet, " is the disposition to economise, that complaints are made should the Commissioner employ an Engineer at a salary of fifteen hundred a year I The subject must be elevated above this, or decent men will cease to be connected with it." Laughable as such difficulties to proper administration as those indicated in this extract may appear, they present in practice serious embarrassment to intelligent and vigorous administration.* His intelligence, his personal * One of the embarrassments to the Levee-reformer, remaining as a consequence of the former employment of non-professional men for Engineering Levees, presents itself in the want of faith amongst even intelligent Planters of the Valley, in the skill and independence of the professional Engineer. Identified widely and favor- ably, as has been the name of Mr. M. Butt Hewson, with the leading measures of public improvement in the South- West, for several years known, as it is, honorably to the professional Engineer, and the Railroad public generally, from New York to New Orleans the Chairman of the Board of Levee-Commissioners for the State of Mississippi, was obliged, in 1855, to go into the defence hinted at in the following remarks from his Report of that year : " The Messrs. Hewson, both M. Butt, the elder, and William, the younger, are Civil Engineers by profession have been schooled to the science have, by competent men, been heretofore employed directing some of the most important public works of the South. Their labors have passed the ordeal of severe criticism ; their competence has not been disputed by those qualified to judge. I cannot be required to stop and argue questions with men who oppose their calculations who urge in opposition thereto, the figures of men who have emerged suddenly from the walks of private life, for convenience sake, to the dignity of Civil Engineers." Sound economy demands the employment of the very best men for the popular and for the professional duties of the Levee ; and these once employed, administrative vigor demands that they be treated with the fullest confidence. Disparagement of the parties entrusted with those important duties, will merely weaken their hands, diminish their efficiency ; and ought to be, therefore, frowned down by the intelligent and judicious, unless, when based on 132 PRINCIPLES AND PRACTICE OP pride, his honest conviction, and his whole property at stake, on the success of the Levees, an advanced man like the Com- missioner for Coahoma ought not to be met, after the experi- ence of the public in those works for fully seven years, with narrow and silly objections to his employment of an Engineer. Simple as the operation of shovelling and loosening earth undoubtedly is, the public in the Yazoo Valley, have not yet realized the fact, that even that simple operation is an import- ant subject of practical science. Millions of dollars national wealth, and national advancement at stake on the shovelling, loosening, and hauling of earth, many of the tax-payers behind the Levee have yet to learn, or to value, the fact that even this item in Leveeing, taken from the blind guidance of the rude and wasteful suggestions of uninformed laborers, has been placed under the infallible guidance of economic inductions incorporated into a few practical laws. Leveeing, in fact, is in every particular an art. It requires more scientific skill, patient reflection, careful instrumentation, and, perhaps, even more practical knowledge of earth-works and foundations, than is required in the Engineering of nine out of ten of the Rail- roads of the country. Besides that, the Engineer entering on such duties, takes the position in his profession on this Conti- nent, of the pioneer of a new set of works, the classifier of a new set of circumstances, the observer of a new set of phenomena ; and consequently, to be professionally that is to say, econom- ically successful as such pioneer, classifier, observer, must be guided from the outset by all the lights of the practice of water-works and of the science of fluids. Railroad Engineering is a beaten track. Uniform in almost all its details, thatdepart- ment of the profession involves, for the greater part, but a mere knowledge of routine rules. Routine practice, then, will constitute but a very poor qualification for a position, that like unmistakable grounds that may be followed up to summary dismissal. No unfit man should be retained ; no fit man should be for the promotion of some petty interest damaged in his efficiency. EMBANKING LANDS FROM EIVER-FLOODS. 133 Leveeing, must make for itself its own rules of practice rules that cannot be made by ever so thorough a knowledge of mere routine, unaccompanied by a knowledge of the principles of practical and scientific Engineering. Thoughtful intelligence, then, appreciating the serious interests at stake in the effici- ency of the Levees, instead of carping at the placing of the professional duties of the Levee-system in the hands of a regu- larly trained Engineer, in conjunction with the most able, enlightened, and honest man to be found for discharging the popular duties of the system, would rather have suggested its serious apprehension that his acceptance of a salary so small as $1500, place in a doubtful light the professional fit- ness of the Engineer charged with duties so delicate and responsible. The terrible lesson of the- flood just subsiding, will, however, force the property and the purpose of the great Valley to action action guided by all the lights of the broadest and most liberal intelligence. It is, therefore, hoped that, in order to sustain this expected action, some steps be set on foot for freeing Levee-administration from the popu- lar drawbacks upon its efficiency, by either raising it as far as is practicable above local restraints, or, failing in that, by enabling the popular intelligence controlling the whole sys- tem, to keep pace with the growth of the importance of that system. * * The views of administration presented above, have been endorsed in the late message of Governor McWillie, of Mississippi. In that able document, his Excel- lency holds the following language : " This is a matter in which Mississippi is not alone interested, even on her own Levees. All tho States, above and below her, along the river bank from Cairo down, are subject to the same inundation, and mu- tually act and react upon each other. The Levees of any one State are parts of a chain of Levees ; and the direction, restraints, and flow, of the waters of the Missis- sippi through, or past any State, are portions of the forces which affect its regimen everywhere, but most strongly in the Counties below. * * * No elaborate plea is necessary to prove the importance of having a Levee-system for the whole Valley of the Mississippi, framed on sound principles of science, and in concert among the States interested." Change of administration widening and concert of the several existing areas of administration are felt on all hands to be necessities, and the best means of remedying this necessity practically is, undoubtedly, that of the District Drainage system extended to the organization of a general council. 134 PRINCIPLES AND PRACTICE OP CHAPTER IX. EARTH WORK CALCULATIONS. The Prismoidal Formula constitutes the only rule by which regularly sloped embankments can be measured correctly. This rule is as follows : To the sectional area of each end add four times the area of the middle section ; one-sixth of the result- ing sum multiplied by the length of the prism, gives the solid content. If lineal yards be the units employed in the calcula- tion, the direct result of the rule will be cubic yards ; but if lineal feet be the units employed in the calculation, then the direct result of therule being cubic feet, must, to express itself in cubic yards, be divided by 27. This formula supposes the embankment to be a regular prism the actual height of crown and width of base midways between the two ends, being the arithmetical mean one-half the sum of the corresponding heights and widths, respectively, of the two ends. The end areas, then, must never exceed such limits as include between them observable inequalities of ground the supposition of the rule being that the end areas have been taken at intervals sufficiently close to have broken the irregularities of the work into a series of uniformly sloping prisms. The " sectional area" referred to in the rule is the production of the arithmet- ical mean half the sum of the width of crown and width of base by the height. The 100 feet chain is that employed by Engineers in order by tafeg the end areas, whenever practi- cable at that distance asunder, to simplify the above prescribed rule for multiplying by the length. This multiplication in the EMBANKING LANDS FROM RIVER-FLOODS. 135 case of stations 100 feet asunder is made by removing the decimal point two figures to the right ; or when multiplying a whole number by the addition to it of two cyphers. Lineal feet being generally the unit of measurement, the prismoidal formula involves in general a division by 27 to reduce its result to cubic yards ; and as it involves also a previous division by 6, it is somewhat of an abridgment when working it out in detail to divide the sum of the end areas and four times the middle area, after removing the decimal point two figures to the right, by 162 six times twenty-seven. In order to explain more clearly the working out of a measurement under the prismoidal formula, let it be required to calculate the number of cubic yards in a regular embankment 100 feet in length, ten feet high at one end, and 4 feet high at the other end, the crown having the uniform width of 5 feet, the base of the slopes being proportional to the height as six to one. The base for the end 10 feet high is (six times 10 for the slopes and 5 feet for tvidth of crown) 65 feet ; and one-half the sum the arithmet- ical mean of the width of base and width of crown being (65 and 5 divided by 2)' 35, the product of the arithmetical mean by the height (35 by 10) is 350, the area at the large end. By a like process the sectional area for the small end is 68. The arithmetical mean one-half the sum of the heights at both ends is (10 and 4 divided by 2) 7 the height of the middle section. The area corresponding to this height, by the calculation explained before, is 182 ; and this multiplied by 4 gives a product of 728 4 times the middle area. 350 (one end area) and 68 (the other end area) and 728 (4 times the middle area) show a total of 1146 ; and this multiplied by the length being 114600, one-sixth of the product divided by 27 (or 114600 divided by 162) shows a quotient of 707.40, the content of the embankment, in question, in cubic yards. To explain this more clearly it is better to repeat the same calculation in another form : 136 PRINCIPLES AND PRACTICE OF GREATER END. LESS EMD. 10 (height) 4 (height) 6 rate of slope, 6 rate of slope, 60 base of slopes, 24 base of slopes, 5 base of crown, 5 base of crown, 65 width of base, 29 width of base, 5 width of crown, 5 width of crown, 2)70 sum of widths, 2)34 sum of widths, 35 arithmetical mean, or half the 17 arithmetical mean, or half the sum of the width of crown, sum of the width of crown, and of base. and of base. 85 arithmetical mean width, 17 arithmetical mean width, 10 height, 4 height, 850 sectional area. 68 sectional area. MEAS AREA. 10 height of greater end, 4 height of less end, 2)14 sum of the two heights. 7 mean height. 6 rate of slope, 42 base of slopes, 5 base of crown, 47 width of base, 5 width of crown, , 2)52 sum of widths, 26 arithmetical mean or half the sum of the width of crown and of base. 26 arithmetical mean width, 7 height, 182 sectional area, 4 multiplier, 728 four times the middle area. SUMMATION. 350 area of greater end, 68 area of less end, 728 four times middle area 1146 aggregate of areas, 100 length, 6)114600 product of aggregate by length, 27)19100 content in cubic feet, 707.40 content in cubic yards. EMBANKING LANDS FROM RIVER-FLOODS. 137 This then is the full detailed method of earth-work estimation in accordance with the prismoidal formula. Before offering any further remarks on the subject, it is better to meet here the prevailing practice of estimation among the unskilled men charged with the " Engineering" of Levees, by some compari- sons with the above the correct practice. The methods of calculation in common use on all the Levees of both Arkansas and Mississippi with the exception of those in Coahoma, where Col. Alcorn has taken the trouble to acquire perfect facility in the correct practice himself are those by average heights and by average end areas. These S} 7 stems are wrong in principle ; but, in the popular spirit by which these remarks have been guided, waving the error of principle, the most effective corrective in the case will be an illustration of that error in practice. The prismoidal formula has already been worked out in detailing the measurement of a Levee ten feet at one end and four feet high at the other end, the width of crown being uniformly 5 feet ; and the aggregate rate of side elopes 6 to 1. The content of this embankment will now be detailed according to the two rules of measurement pursued generally on the Mississippi : BY AVERAGE HEIGHTS. 10 height at greater end, 182 area for average height, 4 height of less end, 100 length, 2)14 sum of heights, 27)18200 content in cubic feet, 7 average height, 674.00 content in cubic yards. 6 rate of slope, BY AVERAGE AREAS, 42 base of slopes, 5 base of crown, 350 area of greater end, 68 area of less end, 47 width of base, 5 width of crown, 2)418 sum of areas, 2)52 sum of widths, 209 average area, 100 length, 26 half sum of widths. 7 average height, 27)20900 content in cubic feet, 182 area for average height, 774.00 content in cubic yards. 138 PRINCIPLES AND PRACTICE OP By this method of average heights, then, the solid content of the embankment in question, would be taken at 674 cubic yards ; and by the method of average areas at 774 cubic yards ; a difference that at fifteen cents a yard, showing a discrepancy of $15 for 100 feet of Levee, would sum up at the same rate to an immense sum when repeated for every 100 feet along the whole extent of even a County. But the fact of the case is ; both of the quantities are wrong ; and the one that by aver- age areas being wrong in its excess, is an injustice to the tax-payer, while the other that by average heights being wrong in its deficiency, is an injustice to the contractor. The true quantity, as given in accordance with the prismoidal for- mula, has been shown in detail to be 707 cubic yards. The quack-systems then, and the correct system, compare in the case under consideration as follows : 674 cubic yards the content by average heights. 707 cubic yards the content in fact. 774 cubic yards the content by average area. One of the common systems, then, of calculation by average heights is an injustice in the instance under consideration, at the rate of $261 per mile to the Levee contractor ; the other and equally common system is an injustice in the same instance at the rate of $531 per mile to the Levee-tax-payer. This assumes the cost of the work at 15 cents per cubic yard. The error of these modes of calculation are sometimes less than in the case presented above ; but they are also, sometimes, even still greater : with end-areas and end-heights nearly equal, they are very trifling ; but with end-areas and end-heights differing largely, those errors become very serious. For the width of crown and rate of base adopted in the above exam- ple, the excess of result, according to the system of average areas for example, increases over the true content of the prism according to the following gradations : for lengths of 100 feet, EMBANKING LANDS FROM RIVER-FLOODS. 139 where the inequality of the heights of the two ends is, 1 foot, the excess given by the method of average areas, is 1.6 cubic yards. 2 feet, do do 7.5 cubic yards. 3 feet, do do 17.0 cubic yards, 4 feet, do do 30.0 cubic yards. 5 feet, do do 46.0 cubic yards. 6 feet, do do 66.6 cubic yards. 7 feet, do do 90.7 cubic yards. 8 feet, do do 118.5 cubic yards. Adopting still the five-feet crown and six-fold base, the insuffi- ciency of the quantities resulting from the process of average heights, follows the following gradations : with a length of 100 feet where the inequality of the heights of the two ends is, 1 foot, the deficiency by the method of average heights, is 0.8 cubic yards. 2 feet, do do 3.7 cubic yards. 3 feet, do do 8.5 cubic yards. 4 feet, do do 15.0 cubic yards. 6 feet, do do 23.0 cubic yards. 6 feet, do do . 33.3 cubic yards. 7 feet, do do 45.4 cubic yards. 8 feet, do do 59.3 cubic yards. It may be noted here that the calculations by average heights are always a wrong to the contractor, those by the average area being always a wrong to the public the deficiency in the one case being one-half that of the excess in the other case. But, bad as are both of those methods when applied to even short lengths of embankment, a very common practice in the use of both, by extending the averages to considerable lengths, make the evil still greater. The following table shows the heights, crown, and base of a Levee, taken at regular intervals of 100 feet ; extracted from a measurement-book of my own prac- tice on Levees, it represents an actual state of facts. The last column shows the content of each 100 feet of the embank- ment, according to the prismoidal formula the true content in cubic yards. 140 PRINCIPLES AND PRACTICE OF Stakes. Heights. Widths. Contents in cubic yards Crown. | Base. | 1210 3.30 20.16 1211 2.59 15.54 124.9 1212 1.77 10.60 74.3 1213 1.60 9.60 47.5 1214 1.43 8.58 39.2 1215 1.80 10.80 43.7 1216 2.62 15.12 71.8 1217 1.74 10.44 71.4 1218 3.00 18.00 85.0 1219 3.72 22.32 156.1 1220 3.18 19.08 104.5 1221 3.91 23.46 173.6 1222 3.73 22.38 190.4 1223 3.63 21.78 180.3 1224 2.60 15.60 137.1 1225 196 11.76 79.9 1226 6.28 37.68 243.0 1227 9.40 66.40 7ti6.2 1223 7.58 45.48 R84-5 1229 12.38 74.28 1225 1 1230 11.26 67.56 1659.8 1231 8.69 52.14 1207.8 1232 10.23 61.38 1283.9 1233 8.66 51.96 1082.2 1234 7.66 45.96 814.4 1235 7.49 44.94 704.7 1236 8.60 51.00 786.1 1237 8.74 52.44 003.1 1238 7.47 44.82 805.6 1239 6.12 36.72 577.1 1240 3.04 18.24 285.3 1241 2.10 12.60 97.2 1242 1.75 10.50 60.0 1243 1.63 9.78 47.9 1244 1.76 10.56 47.9 1245 2.09 12.54 60.0 1246 2.22 13.32 71.4 1247 3.49 2C.94 118.3 12-18 3.47 20.82 167.9 1249 8.43 20-58 164.4 1250 3.42 2052 160.7 Total cubic yards, .... 15,670.2 The true content of the above Levee 4,000 feet long was 15676 cubic yards. Now, the average height of all the stations on this piece of work was, as may be seen by adding up the above column of heights, and dividing the sum by the number of heights so added, 4.67 feet. The average width correspond- ing to the average height, being 16.51 feet, the area the product of this average height by its average width is 77.10 square feet. To repeat this in another form : 16.51 the average width corresponding to a height of 4.G7 feet. 4.67 the average height of the whole embankment. 77.10 the average area by a general average height of the whole bank. 4000 the length of the whole bank. 27)308400, content of whole bank in square feet. 11422.22, content of whole bank in cubic yards. EMBANKING LANDS FROM RIVER-FLOODS. 141 The comparison in this instance then, stands thus : 15672 cubic yards, the true content. 11422 cubic yards, the content by a general average height. 4250 cubic yards of error against contractor. The contractor, in this instance, paid nominally, 15 cents per yard for his work, would, in fact, be paid according to this sys- tem of measurement, at the rate per yard of less than 11 cents. The contractor, however, is generally able to secure fair play for himself ; but in the case of those methods of calculation that, pursued as they are by officers of the public, give the contractor a large excess above his just rights, there is no pro- tection to save that public, when it contracted for but 15 cents a yard, from paying, in consequence of the unfitness of its own officer its " Engineer" so high, in fact, as even 20 cents a yard. So important is it to both the contractor on Levees, and to the public paying for their construction, that a system of measurement be laid down that, adapted to the popular under- standing, may secure to both parties mutual, even-handed justice. The errors of the systems common in measuring Levees thus exposed, attention may be now recalled to the prismoidal rule. The illustration given of that rule will have suggested that its employment at intervals of 100 feet, and of less, along a line of Levee, makes correct estimation, a process most elaborate and tedious. Practice, however gives a surprising expertness in casting up quantities directly ; and also in the use of regular forms of calculation, suggests from time to time several meth- ods of abridgement. For a regular rate of slope, for instance, the Engineer about to estimate any considerable stretch of work, finds it much more correct and rapid to calculate, in the first place, a regular table for that slope ; and applying that table to the special dimensions of his measuiement, take off prismoid after prismoid, by inspection. For new Levees such 142 PRINCIPLES AND PRACTICE OP a table is directly applicable. Tables 1, 2, and 3, have, accord- ingly, been added at the end of these remarks, for the use of the less expert and indeed, also, of the more expert to whom the elaboration necessary, otherwise, may be an obstacle to the general introduction in Levee-measurement of the pris- moidal formula. These calculations are intended to cover all the forms of section prevailing in the Levee-practice of the Mississippi. In terms representing cubic yards, the tables show, for prisms of 100 feet long, the " end area," and " four times middle area" for all heights to tenths and half tenths of a foot, from, a height of one foot to a height of 24.95 feet. Table No. 1 is estimated for a base-width of 6 feet hori- zontal to 1 foot vertical ; and with a crown of 5 feet wide the dimensions allowed by the Superior Board of Levee Commissioners for the State of Mississippi. Table No. 2 is estimated for a base, bearing the same constant proportion to the height ; but differing from table No. 1 in having a crown of only 3 feet wide. No. 3 gives the quantities under the same heads, in the same terms, and for the same intervals, for a Levee having a crown of 3 feet across ; but with a base having a width of seven times the height. The dimensions given in this table, are those generally used in the State of Arkansas, with the exception of the width of crown ; the adopted crown-width being, as before remarked, erroneous in principle. In measur- ing the Levee it is, in fact, not practicable to arrive at a greater accuracy in the heights than a tenth of a foot. The tables are accordingly, in being extended to tenths, carried out to the full- est detail available in practical estimation. In order to show in juxta-position a calculation made in detail, and the same made under the abridging of the above table, let it be proposed to cast up the quantities in a Levee 100 feet long, 3.60 feet in height at the less end, and 7.70 feet in height at the greater end, the base being always six times the height, and the crown of the uniform width of 5 feet. EMBANKING LANDS FROM RIVER-FLOODS. 143 PRISMOIDAL FORMULA WORKED OUT IN DETAIL. GREATER END. LESS END. 7.70 height, 3.60 height, 6 multiple for base, 6 multiple for base, 46.20 width of base, 21.60 width of base, 5.00 width of crown, 6.00 width of crown, 2)51.20 sum of width, 2)26.60 sum of width, 25.60 mean or half sum of width 13.30 mean or half sum of width, 7.70 height, 3.60 height, 1792 399 197.1200 sectional area. 47.8800 sectional MIDDLE AREA. 7.70 height at greater end. 3.60 height at less end, 2)11.30 sum of heights 5.65 mean or half sum of heights, 6 multiple for base, 33.90 width of base, 5.00 width of crown. 2)38.90 sum of width. 19.45 mean or half sum of widths, 5.65 mean height, 9725 11670 9725 109.8925 middle area. 4 multiple according to rule, 439.57 four times middle area, 197.12 area at greater end, 47.88 area at lesser end. 6)68457 sum of areas, 114.095 one-sixth the sum of areas, 100 length. 27)114095 (422.6 solid content in cubic yards. 108 155 162 144 PRINCIPLES AND PRACTICE OP Such is the regular working out of this quantity in detail. Let it now be worked out by the tables. The crown being five feet and the base six times the height, the table to be employed in the case is No. 1. Turning then to No. 1, under the head of three feet and on the line corresponding to the decimal .60 in the margin, the tabular " end area " corresponding to 3.60 is found to be 29.6 ; under the head of 7 feet and on the line of the marginal decimal .70, the end area in the table is 121.7. Adding together 3.60 the height at one end, and 7.70 the height at the other end, the aggregate is 11.30 ; and this sum divided by 2 shows for the middle height, 5.65 feet. Turning again to the table, the tabular number under the head 5 feet, and on the line .65, is found in the column of " middle areas " to be 271.4. Adding 271.4 (four times the middle area) 29.6 (the area at the less end) and 121.7 (the area at the greater end) the total is 422.7. This explanation of the use of the tables thus given, the comparison with the above detail may be now commenced. 3.60 less height tabular " end area" corresponding, - - 29.6 7.70 greater height tabular " end area" corresponding, - - 121.7 2)11.30 sum of heights. 6.65 middle height tabular " 4 tunes middle area" corresponding, 271.4 Solid content, by prismoidal formula, in cubic yards, - - 422.7 The figures in each process show at a glance the facilities fur- nished by the table the detail process requiring 208 figures, and tabular abridgement but 29 figures. The tables, then, may be held as reducing the time and labor of calculations by the prismoidal formula to one-seventh the time and labor neces- sary in carrying out that formula in detail. These tables are altogether new the result of using the formula extensively when cutoif from an opportunity of reference to any other system of calculation by inspection. Original in every partic- ular as they are, it is, perhaps, better to explain more fully than has been done in the foregoing comparison, the use and EMBANKING LANDS FKOM RIVER-FLOODS. 145 convenience of those tables. Passing to tnis explanation, it may be observed that the quantities employed in the table are fictitious, representing no reed quantity, until the summation into a solid content, when they take the form of cubic yards. Extracting the heights at each station from the level-book, these are transferred, in the office, to the measurement-book in the following manner. The column showing the distances between the several stations (see annexed form) are to be filled up with those distances, leaving every second line blank. The heights, respectively, corresponding to those distances are then transferred to the column of heights, each opposite its own distance, and consequently entered, like the distances, on every second line. The third column of the measurement-book is next filled in with the quantity constituting an arithmetical Form of Measurement Book adapted to Tables Nos. I., JL, and HI. Distance Station. End Heights. Mean Heights. Tabular Number. Contents in Cubic Yards. Remarks. 6.00 54.1 6.10 224.2 100 6.20 6.50 581 258.0 886.4 68.1 belonging to this pris- moid is included therein, 200 6.80 71.3 887.4 and belonging also to the 800 6.30 6.65 262.4 C0.2 893.9 following, is included in that, too. 5.50 258.0 400 5.70 69.0 387.2 6.45 848.0 COO 7.20 107.1 6241 13.40 1412.8 13 feet 19.60 741.7 294.0 Special calculation. mean between each pair of heights entered in the second col- umn this mean being, of course, one-half the sum of its corresponding pair of end-heights. These mean heights are entered in the lines that had been left blank, when filling in the first and second columns ; and thus occupy, in the mea- surement-book, a place between the two heights, from which each of them is deduced. The end-heights, and mean heights thus filled in and placed in proper position in the measure- ment-book, the calculator will next call to his assistance the 146 PRINCIPLES AND PRACTICE OP earth-work tables. In doing this, it must be recollected that each set of heights in the tables, having corresponding to it two different sets of quantities that in the column of " end- areas," and that in the column of " 4 times the middle height" the only certain mode of guarding against the use of one of these for the other, is to first take out the quantities under one head those for the measurement-column of" end-heights," first ; and all these completed, then take out the quantities under the other head those for the measurement-column of " mean heights." The first " end-height," then, is 5.00. Turning to table No. 1, the eye rests on the head in large characters " 5 feet." Running down the margin, the decimal " 00" is seen ; and the " end-areas" under the heading " 5 feet" on line " 00" is found to be 54.0. Under the head, Tabular numbers of the measurement-book, this 54.0 is then entered on the line running across the book from the end-height 5.00. The head- ing " 5 feet," being again used in the tables, the eye rests in the next place on the marginal decimal .20 ; and the " end- area" under the head " 5 feet," corresponding to the decimal .20, is seen to be 58.1. The 58.1 is, then, entered in the col- umn of " tabular numbers" of the measurement-book, on the line running across the book from the corresponding height of 5.20. So, also, with all the other " end-heights." These com- pleted, the next duty is to take out the tabular numbers for the " mean heights." These, be it remembered, are found in the column " 4 times middle area." The first mean height in the above form of measurement-book, is 5.10. Again, under the head " five feet," after running down the margin to the decimal .10, the eye rests on the tabular number corresponding to 5.10 in the column ' 4 times the middle area." This num- ber is seen to be 224.2. Opposite to, and on the line running across the measurement-book from, " mean height" 5.10, this number, 224.2 is next entered in the column of tabular num- bers. The mean heights are thus gone through, one after the EMBANKING LANDS FROM RIVER-FLOODS. 147 other. The use of the tables ended, the next step is the sum- mation. This must be done by grouping together each three quantities in the column of " tabular numbers" always taking care that, after that quantity corresponding to the first distance the quantity corresponding in the column of " tabular num- bers" to each distance, or to each " end height," shall be used in the additions twice once, in addition to the two quantities above it, and again, in addition to the two quantities below it, in the measurement-book. The column " content in cubic yards" thus made out for each distinct prism, the addition of all completes the measurement. This supposes the stations, it will be observed, separated by uniform distances of 100 feet each. In irregular ground, however, the stations must be separated by irregular intervals in bayous, for instance, it being often necessary to place them so close together as 4 or 5 feet. The measurement-book in such cases is filled, as shown between stations 4 and 5 in the above form, the prisms being made subjects of special calculations. These calculations may be made with a saving of time and trouble by adding the tabu- lar numbers corresponding to its end-heights, and to its mean height as described for the 100 feet lengths ; and multiplying the sum of these numbers by the length of the short prism in question ; the removal of the decimal in the product, two fig- ures to the left, will give the true content of that prism. Suppose, for illustration, a prismoid of 13 feet length, 7.20 feet at one end, and 19.60 feet at the other end. This has a mean height of (one-half the sum of its end-heights) 19.60 added to 7.20, and the sum divided by 213.40. 7.20 end height has a tabular " end area" of - - - 107.1 19.60 end height has a tabular end'area of - 741.7 13.40 mean height has a tabular "4 times middle area" of - 1412.8 Total, - - 2261.6 Multiplied by length - - 13 Cubic yards in the 13 feet prism - - 294.00.8 148 PRINCIPLES AND PRACTICE OF This will save some trouble, as otherwise the calculation for the 13 feet must be made under the formula in extenso. The remaining quantities in the above form of measurement are obtained in the same manner as those of the foregoing expla- nations. The quantities of embankments having a crown of 3 feet across and a base of six-fold width, are to be calculated by table No. 2. A seven-fold width of base having a crown of 3 feet wide presents a section whose quantities must be calcu- lated by table No. 3. The use of these two tables is precisely similar to that of table No. 1. Tables 1, 2, and 3 are confined in their application to new or well preserved embankments. Old Levees, however, with worn crowns, hollowed sides, and spread bases, cannot be meas- ured with any approach to truth by a rule based on a uniform width of crown and constant rate of base. Estimation under such circumstances can be made only by a series of careful cross-sectioning ; and in order, therefore, to meet this necessity of the present works in Levee management, a table of contents is added here on the basis of sectional areas. Table No. 4 aims at this object. Irregular works being the special subject for the use of this table, it may be necessary to observe that it is equally applicable to works of uniform sections. The rule for using table No. 4 is as follows : For lengths of 100 feet add to the cubic yards corresponding in the table to each of the given end areas, 4 times the cubic yards corresponding to the mean o/ those two areas, and the sum will be the content of the bank in cubic yards. Or another rule for using table No. 4 : Add for lengths of WO feet the two end areas to 4 times the mean of those two end areas, and the number corresponding in the table to the total of these is the content of the bank in cubic yards. For shorter lengths than 100 feet, multiply the result in either of the above rules by the length, and changing the decimal point two figures to the left, the product is the content in cubic yards. The sectional areas in the tables are given, it may be observed, EMBANKING LANDS FROM RIVER-FLOODS. 149 in square feet. Taking a few of the prismoids in the form of measurement-book already given, the sectional areas are as follows, as estimated by table No. 4 : Form of Measurement- Book for Table No. IV. Sectional Contents in Crown. Base. Average widths. Areas. Cubic Yards. 5.00 5 80.00 17.50 87.50 1 5.20 5 31.20 ,18.10 94.12 336.8 104.77 2 5.80 5 84.80 19.90 115.42 883.0 106.47 3 5.30 5 81.80 18.40 97.52 894.0 104.63 4 5.70 5 84.20 19.60 111.72 887.4 First prisrnoid less end area 87.50 greater end area 94.12 4 times middle area 363.24 Total 544.80 The solid content corresponding in table No. 4 to this aggre- gate " area" 544.86 is 336.4 cubic yards. Second prismoid less end area 94.12 greater end area 115.42 4 times mean area 419.08 Total 628.62 Running the eye down the column "areas in square feet " of table No. 4, it rests on the large figures 620 ; and following down the column to the single figure 8, the number corres- ponding to 628 is seen to be 387.6. By the aid of the auxil- iary table subjoined to table 4 the proportional value in cubic yards corresponding to the decimal of the areas, .62 is to be added to the solid content of the whole numbers. The cubic yards corresponding to the aggregate area of 628.62 shows, therefore, a solid content of 388.0 cubic yards. This explanation is sufficient to make the use of table No. 4 perfectly clear. For 150 PRINCIPLES AND PRACTICE OP the particular measurements contemplated by this table it will be found a most valuable assistant to the calculator who aims at close and careful calculation. All the tables in this book are new to the profession ; tables 1, 2, and 3, being modifications from the practice of Mr. M. Butt Hewson ; table No. 4 being, however, purdy original. Tables Nos. 1, 2 and 3, respectively, condense in a small sheet con- taining 60 lines and 16 columns, a number of results in cubic yards that cannot, in the ordinary diagonal tables of earth-works, be given in a smaller space than that occupied by 480 lines and 480 columns. Earth-work tables in general, limit their facilities to heights of full feet ; and therefore, tables 1, 2, and 3, an- nexed to this, while much more condensed in form and much more facile of reference, make a great advance in going into detail so minute as that involved in heights of feet and tenths of a foot. It is perhaps unnecessary to state that all these tables are equally applicable to cut and to bank, whether on Levee, Canal or Railroad. In conclusion it may be added that these remarks, whether in theory or in practice, have been of necessity generalities. Engineering on Levees is in the crude state of those improve- ments, work for a man of some original observation, some original resources, some scientific and practical skill. Correct measurement will be brought by the remarks made above within the compass of men of intelligence under ordinary circumstances ; but the special circumstances for even separa- ting Levee-practice from general rules spreading of base, sinkings of foundations, bulgings of sides, inundating of work- pits, &c. make it necessary for proper estimation of those works that they be always placed in the charge of some one thoroughly conversant with the elementary principles of meas- urement. Location alone involves so many delicate and intri- cate considerations these again involving so many serious if not fatal contingencies as to require, superior to all rules of EMBANKING LANDS FROM RIVER-FLOODS. 151 practice the eye and mind of a professional Engineer. The detail surveys suggested above are undertakings, too, that in the hands of even a decent pretender to professional ability will result in a simple waste of money. The Trigonometrical survey for connecting the Levees on both sides of the Eiver is a duty from which (let unfitness be ever so ready to undertake it) even the regular Engineer, who has never directed his mind or his practice to such a system of survey, will be found in honor and self-consciousness to decline. Finally : if any- thing that has been said here shall further the interests of Levees, shall bring those works more thoroughly within the rules of art, shall strengthen the hands of the administrator entrusted with their charge, or shall correct errors of opinion on the part of planters and others hampering the intelligence of his aims, the writer shall have felt rewarded with the satis- faction of having left the impress of his experience in the great Valley after him as a souvenir for the benefit, in a greater or less degree, of the very highest interests of a generous people, amongst whom he has spent many a happy day of work and pleasure. THE END. TABLES Nos. 1, 2, 3, and 4 154 PRINCIPLES AND PRACTICE OF TABLE I. Table of cubic yards corresponding to a cross section Decimals of a foot. End areas. 4 times middle area. Knd areas. 4 times middle area. End areas. 4 times middle End areas. 4 rime* middle Decimals of afoot. 1 foot. 2 feet 3 feet. 4 feet. .00 8.4 13.6 10.5 42.0 21.2 84.8 85.8 143.2 .00 .05 3.1 14.7 10.9 43.8 21.9 87.6 866 146.5 .05 .10 8.9 158 11.4 45.6 22.6 90.3 87.5 149.8 .to .15 4.2 16.9 11.9 47.6 23.2 93.0 . 888 153.8 .15 .20 4.5 18.1 12.4 49.4 23.9 95.6 156.6 .20 .25 4.3 19.4 12.8 61.4 24.6 938 4o!l 160.6 .25 .30 5.2 20.7 134 53.4 253 101.0 40.9 163.5 .30 .85 5.5 21.9 13.8 55.4 25.9 1038 41.7 167.0 .35 .40 5.8 23.2 14.4 67.5 26.7 106.6 42.6 170.6 .40 .45 6.1 24.5 14.9 59.6 27.4 109.5 43.5 174.2 .45 .50 6.5 25.9 15.4 61.7 28.1 112.4 44.4 177.8 .50 .55 6.8 27.8 16.0 63.9 28.9 115.5 45.3 1814 .55 .60 72 28.8 16.5 661 29.6 118.2 463 185.1 .60 .65 7.6 30.3 17.1 63.4 80.3 121.2 472 188.9 .65 .70 80 31.9 17.7 70.6 81.1 1242 48.2 192.6 .70 .75 8.4 83.5 182 73.0 81.8 127.3 49.1 196.5 .75 .80 8.8 85.1 18.8 75.4 82.6 130.4 50.1 200.3 .80 .85 9.2 86.8 19.4 77.8 83.4 188.6 61.0 204.2 .85 .90 9.7 8S.5 20.1 80.2 842 136.7 52.0 203.2 .90 .95 10.0 40.2 20.6 82.5 85.0 140.0 53.0 212.1 .95 5 feet 6 feet. 7 feet 8 feet .00 54.0 216.1 75.9 803.7 101.5 406.2 130.9 623.5 .00 .05 55.0 220.1 77.1 808.5 102.9 411.7 182.4 529.7 .05 .10 56.0 224.2 78.8 813.8 104.3 417.3 134.0 536.0 .10 .15 5T.O 228.2 79.5 818.1 105.7 422.8 185.6 542.3 .15 .20 58.1 232.4 80.8 8230 107.1 423.4 137.2 548. 7 .20 .25 59.1 236.6 82.0 827.9 108.5 431.1 13S.8 555.1 .25 .30 60.2 240.8 88.2 332.9 110.0 439.8 140.4 561.5 .30 .85 61.2 245.0 84.5 837.9 111.4 445.5 142.0 563.0 .35 .40 62.3 249.3 857 842.9 112.8 ' 451.3 143.6 574.5 .40 .45 63.4 253.7 87.0 348.0 114.3 457.1 145.3 531.1 .45 .50 64.5 25S.O 88.8 853.1 115.7 463.0 1469 587.7 .50 .55 65.6 262.4 89.5 858.2 117.2 46S.8 1486 594.3 .55 .60 66.7 266.9 90.9 8fi3.4 118.7 474.8 150.2 600.9 .60 .65 67.8 271.4 92.1 863.6 120.2 480.7 151.9 607.6 .65 .70 69.0 275.9 93.5 8739 121.7 486.7 15^.6 614.4 .70 .75 70.1 280.4 94.8 879.2 123.2 492.7 155.3 6211 .75 .80 71.3 285.0 96.1 8S4.5 124.7 498.3 157.0 628.0 .80 .85 72.4 289.6 97.5 889.9 126.2 504.9 153.7 634.8 .85 .90 78.6 294.8 9S.8 895.8 127.8 511.1 160.4 641.7 .00 .95 74.7 299.0 100.2 400.7 129.8 617.2 162.1 648.6 .95 9 feet. 10 feet. 11 feet. 12 feet. .00 1689 655.6 200.6 802.5 241.1 964.2 2852 1140.7 .OO .05 165.6 662.6 20-2.5 810.2 243.2 972.7 287.5 1150.0 .05 .10 167.4 669.7 204.5 818.0 245.8 981.2 2398 1159.2 .10 .15 169.2 676.7 2064 825.8 247.4 9S9.8 292.1 1163.5 .15 .20 170.9 683.8 208.4 833.6 249.6 998.3 294.5 1177.8 .20 .25 172.7 690.9 210.4 841.5 251.7 100H.7 296.8 11873 .25 .30 174.5 698.1 2124 849.4 253.9 1015.6 299.2 1196.7 .30 .85 176.3 705.3 214.3 857.4 256.1 1024.8 801.5 1206.1 .85 .40 178.1 712.5 216.3 865.4 258.3 1033.0 803.9 1215.5 .40 .45 180.0 719.9 218.3 873.4 260.4 1041.8 806.2 1225.0 .45 .50 181.8 727.2 220.4 881.5 262.7 1050.6 808.6 1234.6 .50 .55 1S3.6 734.5 222.4 889. 6 264.9 1059.5 811.0 1244.2 .55 .60 185.5 741.9 224.4 897.7 267.1 1068.4 813.4 1253.8 .60 .65 187.8 7494 226.5 905.9 269.3 1077.8 815.8 1263.4 .65 .70 189.2 756.8 228.5 914.1 271.6 1086.2 818.8 1273.1 .70 .75 191.1 764.4 230.6 922.4 273.8 1095.2 820.7 1282.9 .75 .80 193.0 771.9 232.7 930.7 276.1 1104.2 823.2 1292.6 .80 .85 194.9 779.5 234.7 939.0 278.3 1113.3 825.6 1302.5 .85 .90 196.8 787.1 23G.8 947.4 280.6 11-22.4 828.1 1312.3 .90 .95 198.7 794.8 238.9 955.8 282.9 1131.6 830.5 1322.2 .95 EMBANKING LANDS FEOM RIVER-FLOODS. 155 TABLE I. (Continued.) 5 feel wide on top and 6 feet wide at base for every foot high. Decimals of a foot. End middle area. End areas. 4 times middle area. End areas. 4 times middle area. Knd 4 times middle Decimals of afoot. 13 feet. 14 feet. 15 feet. 16 feet. .00 333.0 1332.1 384.6 1533.3 439.8 1759.3 498.8 1995.1 .OO .05 835.5 1342.1 387.2 1549.0 442.7 1770.8 501.8 2007 2 .05 .10 3880 1352.0 15597 445.5 1782.2 5049 2019.4 .10 .15 3405 1362.1 392! 6 1570.5 4484 1793.7 507.9 2031.7 .15 .20 343 1372.2 395.3 1581 3 451.3 1805.2 511.0 2044.0 .20 .25 345.6 13823 39S.O 1592.2 4542 1816.8 514.1 2056.4 .25 .30 348.1 1392.4 400.8 1603.0 457.1 1828.4 517.2 20687 .30 .35 850.6 1402.6 403.5 1613.9 4600 1840.1 5203 2081.1 .85 .40 853.2 1412.8 406.2 1624.9 462.9 1851.8 5234 2093.5 .40 .45 355. S 1423.1 4090 1635.9 ! 465.9 18636 5'26.5 2106.0 .45 .50 858.8 14333 411.7 1646.9 468.8 1875.8 629.6 ' 2118.5 .50 .55 360.9 1443.7 414.5 1658.0 471.7 1887.0 532.7 21310 .55 .GO 8635 1454.0 417.3 1669.1 474.7 1898.7 535.9 2143.6 .60 .65 , 366.0 1464.0 420.1 1680.3 477.7 1910.7 539.1 2156.3 .65 .70 36S.7 1474.9 4229 1691.4 480.7 1922 8 542.2 2168.9 .70 .75 871.3 1485.4 4'Z5.6 1702.6 483.7 1934.7 545.4 2181.7 .75 .80 374.0 1495.8 428.5 1713.9 486.7 1946.6 548.6 2194.4 .80 .85 S7&6 1506.4 431.3 1725.2 4S9.7 1958.7 551.7 2207.0 .85 .90 379.3 1517.0 . 434.1 1735.6 492.7 1970.8 554.9 2219.6 .90 .95 3S1.9 1527.6 I 436.9 1747.8 4957 1982.9 558.1 2232 6 .95 17 feet. 18 feet. 19 feet. 20 feet. .00 561.4 2245.7 6278 2511.1 697.8 2791.4 7716 8086.4 .00 .05 5616 2258.6 6312 2524.8 701.4 2S05.8 775.4 8101.6 .05 .10 1567.9 2271.6 634.6 253S.5 7051 2820.2 779.2 8116.7 .10 .15 571.1 22S46 63S.O 2552.2 703.7 2834.7 7S3.0 81319 .1C .20 574.4 2297.6 641.5 2566.0 712.3 2849.2 786.8 31472 .20 .25 1 577.7 2310.7 644.9 2579.8 715.9 2S63.7 790.6 8162.5 .25 .30 580.9 2323.8 648.4 2593.6 719.6 2878 3 794.5 8177 9 .30 .85 531.2 23369 651.9 - 2C07.5 723.2 2893 798.3 81932 .35 .40 r>-7 5 2350.1 655.4 2621.4 726.9 2907.6 802.2 .40 .45 590.3 2:;63.3 6588 2635.4 730.6 2922 3 806.0 3224'.0 .45 .50 594.1 2376.6 662.3 2649.4 734.3 2937.0 8099 3239 5 .SO .55 ! 597 5 ' 2389. 9 665.9 2663.5 737.9 2951.8 813.8 3255.1 .55 .60 ||6008 2403.2 669.4 2677.5 741.7 2966.6 8176 8270.6 .60 .65 604.1 24166 672.9 2691.6 745.4 29815 821.5 S2.-6.2 .65 .70 607.5 2429.9 676.4 2705.7 749.1 2996.3 825.4 3301.8 .70 .75 610.8 2443.3 680.0 2719.9 752.8 3011.2 829.4 8317.5 .75 .80 6U.2 2456.8 6S35 2734.1 7566 3026 2 8:33.3 33331 .SO .85 6176 2470.3 6S7.1 27484 760.3 8041.1 837.2 3348.9 .85 .90 621.0 2JS3.9 690.7 2762.7 7641 8056.2 841.2 3364.6 i .90 .95 624.4 2497.5 694.2 2777.0 767.8 8071.3 845.1 83S0.4 | .95 21 feet. 22 feet 23 feet. 24 feet. .OO ! 849.1 33964 930.2 3721.0 10151 4060.5 1103.7 4414.8 .00 .05 |l 853.0 3412 2 934.4 3737.7 1019.5 4077.9 1108.2 44329 .05 .10 857.Q 3423.1 938.6 3754.3 1023.8 4095.3 1112.8 4451.1 .10 .15 861.0 3444.0 942.7 3771.0 1023.2 4112.7 11178 4469.3 .15 .20 | 865.0 3460.0 946.9 3787.7 1032.5 4130 2 1121.9 4487.5 .20 .25 869.0 84761 951.1 8804.5 10369 41477 1126.4 4505.3 .25 .30 873.0 3492.2 955.3 8821.3 1041.3 4165.2 1131.0 4524.0 .30 .85 877.1 3508 3 959.5 3S3S.1 1045.7 4182.8 11856 45423 .85 .40 i 881.1 8524.4 963.8 3855.0 1050.1 4200.4 11402 4560.7 .40 .45 8851 3540.6 9630 3872.0 1054.5 42181 11448 4579.1 .45 .50 889.2 3556.8 972.2 3888.9 1059.0 4235.8 1149.4 4597.5 .50 .55 | 893.2 3573 976.5 3905.9 1063.4 4253.6 1154.0 4616.0 .55 .60 l| S97.8 35S9.3 980.7 39229 1067.8 4271.3 11586 4634.5 .60 .65 <\ 901.2 3605.7 9850 39400 1072.3 4289.1 1163.3 4653.1 .65 .70 1,905.5 3622.1 989.3 8957.1 1076.7 4306.9 11679 4671 7 .70 .75! 1909.6 363S.5 9936 3974.3 10812 4324.8 1172.6 4690.3 75 .80 ! 913.7 ! 3654 9 997.9 3991.4 1 1085.7 4342.7 |j 1177.2 4708.9 .SO ; 917.8 3671.4 1002.1 40i'8.6 1 1090.2 4360.7 I 1181.9 4727.7 .85 .90 ' j| 922.0 8697.9 10065 4025.9 10947 4378 7 1186.6 47464 .90 .95 926.1 3704,4 1010.8 4043.2 II 1099.2 4398.8 i 11913 i 4765.1 .95 1 II !! I 156 PRINCIPLES AND PRACTICE OF TABLE H. Table of Cubic Yards corresponding to a crots section 3 feet wide Decimals of a foot. End areas. 4 times niM.il,; End 4 times middle End areas. 4 times middle End areas. 4 times middle Decimals of a foot. .00 1 2.8 foot. 11.1 2 9.3 feet. 87.0 3 19.4 feet. 77.8 4 88.3 feet- 183.8 .OO .05 8.0 12.1 9.7 88.7 2U.1 80.3 84.1 136.5 .06 .to 83 13.0 10.1 40.4 20.7 82.7 849 139.7 .10 .15 8.5 14.0 10.5 42.2 21.8 85.2 85.7 142.9 .15 .80 8.8 151 11.0 44.0 21.9 87.7 86.6 146.2 .20 .25 4.0 16.2 11.4 45.8 22.7 90.8 87.8 1498 .25 .30 4.3 17.3 11.9 47.7 23.2 93.8 83.2 152.9 .30 .85 4.6 18.5 12.4 49.7 24.0 96.0 89.1 156.8 .85 .40 4.9 19.7 12.9 51.6 24.6 98.2 89.9 159.7 | .40 .45 5.2 21.0 13.4 53.5 25.2 100.9 40.8 163.2 .45 .50 5.6 22.2 13.9 55.5 25.9 103.7 41.7 Kit, 7 .50 .65 5.9 23.5 14.4 57.6 26.6 106.5 42.6 170.8 .65 .60 62 24.9 14.9 59.7 27.8 109.3 43.4 1738 .60 .65 66 26.3 15.4 61.8 28.0 112.2 44.3 177.4 .65 .70 6.9 27.7 16.0 64.0 28.8 115.1 45.8 181.0 .70 .75 7.3 29.2 16.5 66.2 29.5 118.0 46.2 184.9 .75 .80 7.7 80.7 17.1 68.4 80.3 121.0 47.1 188.4 .80 .85 8.1 82.3 17.7 70.7 81.0 124.1 48.0 192.2 .85 .90 8.4 83.8 18.8 73.0 81.8 127.1 49.0 196.0 .90 .95 8.8 85.4 18.8 75.4 82.5 130.2 60.0 199.9 .95 5 feet. 6 feet 7 feet 8 feet. .00 50.9 203.7 72.2 2S8 9 97.2 88S.9 125.9 503.7 .OO .05 51.9 207.6 73.4 293 6 98.6 894.3 127.5 509.9 .05 .10 52.9 211 6 74.6 298.'2 99.9 899.7 129.0 616.0 .10 .15 53.9 215.6 75.7 803.0 101.3 405.2 130.5 522.2 .15 .80 54.9 2196 70.9 807.7 102.7 410.7 132.1 5234 .20 .25 55.9 223.6 73.1 312.5 104.1 416.3 133.7 534.7 .25 .30 56.9 227.7 79.8 817.8 105.4 421.8 135.3 541.0 .30 .85 58.0 231.9 80.5 322.2 106.3 427.4 186.8 547.4 .35 .40 59.0 236.0 81.8 327.1 103.8 433.0 133.4 653.8 .40 .45 60.0 240.2 83.0 832.0 109.7 438.7 140.1 560.3 .45 .50 61.1 244.4 84.3 8=37.0 111.1 444.4 141.7 566.7 .50 .55 a&i 248.7 85.5 342.1 112.5 450.2 143.8 573.2 .55 .60 63.3 253.0 86.8 347.1 114.0 456.0 144.9 579.7 .60 .65 648 257.4 88.0 852.2 115.4 461.8 146.6 536.3 .65 .70 65.4 261.8 89.3 857.3 116.9 467.7 148.2 592.9 .70 .75 60.6 266.3 90.6 8D2.5 118.4 473.7 149.9 599.6 .75 .80 67.7 270.7 91.9 867.7 119.9 479.6 151.6 606.3 .80 .85 6S8 275.4 93.2 873.0 121.4 485.6 153.2 613.0 .85 .90 69.9 279.7 94.6 878.2 122.9 491.6 154.9 619.7 .90 .95 71.1 284.8 95.9 883.6 124.4 497.7 156.6 6265 .95 9 feet. 10 feet. 11 feet. 12 feet .00 158.3 6338 194.4 777.8 234.8 937.0 277.8 1111.1 .OO .05 160.0 640.2 196.3 785.4 236.8 945.4 230.5 1122.2 .05 .10 161.8 647.1 19S.3 793.0 233.4 953.8 232.8 1129.3 .10 .15 163.5 654.0 200.2 800.7 240.6 962.3 234.6 1183.5 .15 .20 165.3 661.0 202.1 808.4 242.7 970.7 236.9 1147.7 .20 .25 167.0 668.1 204.1 816.4 244.8 979.2 239.2 1156.9 .25 .30 163.8 675.1 206.0 824.0 246.9 937.7 291.6 1166.2 .30 .85 17H.5 682.2 207.9 831.8 249.1 996.3 293.9 1175.6 .85 .40 172.3 689.3 209.9 839.7 251.2 1004.9 296.2 1184.9 .40 .45 174.1 696.5 211.9 847.7 253.4 1013.6 293.6 1194.3 .45 .60 175.9 703.7 213.9 855.6 255.6 1022.2 300.9 1203.7 .50 .55 177.7 711.0 215.9 8K3.6 257.7 1030.9 803.3 1213.2 .65 .60 179.6 718.2 217.9 871.6 259.9 1039.7 805.7 1222.7 .60 .65 181.4 725.6 219.9 879.7 262.1 1048.5 803.1 1232.8 .65 .70 133.2 732.9 221.9 8S7.7 264.3 1057.3 810.5 1242.0 .70 .75 185.1 740.8 224.0 895.9 266.5 1066.2 812.5 1251.5 .75 .80 186.9 747.7 226.0 904.0 268.8 1075.1 815.3 1261.0 .SO .85 18&8 755.2 22S.O 912.2 271.0 1034.0 817.6 1270.6 .85 .90 190.7 762.7 230.1 920.4 273.8 1093.0 820.1 1230.2 .90 .95 192.6 770.3 282.2 923.7 275.5 1102.0 322.5 1290.1 .95 EMBANKING LANDS FKOM RIVER-FLOODS. 157 TABLE! H. (Continued.) on top and 6 feet wide at base for every foot high. Decimals of a foot End i times middle area. End 4 times middle area. End areas. 4 times middle End areas. middle area. Decimals of afoot. 13 feet. 14 feet. 15 feet 16 feet .00 825.0 1300.0 875.9 1503.7 430.6 1722.2 488.9 1955.6 .OO .05 327.0 1309.9 878.6 1514.8 483.4 1733.6 491.9 1967.7 .05 .10 829.9 1319.7 881.2 1524.9 436.2 1744.9 494.9 1979.7 .10 .15 332.4 1329.7 383.9 1535.6 489.1 1756.3 498.0 1991.9 .15 .20 334.9 1&39.6 886.6 1546.2 441.9 1767.7 501.0 2004.0 .20 .25 337.4 1349.6 889.2 1556.9 444.8 17792 504.0 2016.2 .25 .30 339.9 1359.6 391 9 1567.7 447.7 1790.7 507.1 2028.4 .30 .85 342.4 1369.7 894.6 1578.5 450.5 1802.2 510.2 2040.7 .35 .40 344.9 1379.7 897.3 15S9.3 453.4 1813.8 513.3 2053.0 .40 .45 347.5 13S9.9 400.0 1600.2 I 456.3 1825.4 516.3 2065.4 .45 .50 3500 1400.0 402.8 1611.1 459.3 1837.0 519.4 2077.8 .50 .55 352.5 1410.2 405.5 1622.1 462.2 1848.7 622.6 2090.3 .55 .60 355.1 1420.4 403.3 1633.0 465.1 1860.4 525.7 2102.7 .GO .65 357.7 1430.7 411.0 16441 468.0 1872.2 528.8 2115.2 .65 .70 3603 1441.0 413.8 16551 471.0 1884.0 531.9 2127.7 .70 .75 362.8 1451.4 416.5 1666.2 . 473.9 1895.8 535.1 214H.8 .75 .80 365.4 1461.8 419.3 1677.3 476.9 1907.7 538.2 2152.9 .80 .85 368. 1 1472.8 422.1 1688.5 479.9 1919.7 641.4 2165.6 .85 .90 ii 870.7 1482.7 424.9 1699.7 482.9 1931.6 544.6 2178.2 .90 .95 H 373.3 1493.2 427.7 1711.0 485.9 1943.6 547.7 2191.0 .95 17 feet 18 feet. 19 feet 20 feet .OO 550.9 2203.7 616.7 2466.7 6S6.1 2744.4 759.8 8037 .OO .05 554.1 2216.5 620.1 2430.3 689.7 2758.7 763.0 8052^0 .05 .10 557.3 2229.3 623.4 2493.8 693.3 2773.0 766.7 8067.0 .10 .15 560.5 2242.2 626.8 2507.4 696.8 2787.4 770.5 8082.2 .15 .20 563.8 2255.1 6303 2521.0 700.4 2301.8 774.8 8097.8 .20 .25 5670 2268.1 633.7 2534.7 704.1 2316.3 778.1 8112.5 .25 .30 570.3 2281.0 637.1 2543.4 707.7 2S30.7 781.9 8127.7 .30 .85 573.5 2294.0 640.5 2562.2 711.3 2345.2 735.7 81430 .85 .40 5768 2307.1 644.0 2576.0 714.9 2359.7 739.6 8153.2 .40 .45 580.0 2320.2 6474 25898 713.6 28743 793.4 81736 .45 .50 5*3.3 650.9 2603.7 7222 2838.9 797.2 8188.9 .50 .55 5S66 2346.5 654.4 2617.7 725.9 2903.6 801.3 32043 .55 .60 539.9 2359.7 657.9 2631.6 7296 2918.2 804.9 8219.7 .60 .65 5932 2373.0 661.4 2645.6 733.2 2933.0 808.8 8235.2 .65 .70 596.6 2336.2 664.9 2659.6 736.9 2947.0 8127 8250.7 .70 .75 5999 2399.6 668.4 2673.6 740.6 29625 816.6 8266.3 .75 .SO 603.2 24129 671.9 2637.7 744.3 2977.3 820.4 32318 .80 .85 6066 24263 675.4 2701.8 748.0 2992.2 824.3 8297.4 .85 .90 609.9 2439.7 679.0 2716.0 751.8 3007.1 828.3 8313.0 .90 .95 6133 2453.2 6325 2730.2 755.0 8022.1 832.2 8328.7 .95 21 feet 22 feet 23 feet 24 feet .OO 836.1 8344.4 916.7 8666.7 1000.9 4003.7 1088.9 4855.6 .OO .05 840.0 3360.2 920.8 3633.2 1005.2 40210 1093.4 4373.6 .05 .10 844.0 3376.0 924.9 3699.7 1009.6 4033.2 1097.9 4391.1 .10 .15 848.0 3391.9 929.1 3716.3 1013.9 4055.6 11024 44097 .15 .20 851.9 3407.7 933.2 8732.9 1018.2 4072.9 1106.9 4427.7 .20 .25 855.9 8423.6 9374 3749.6 1022.6 4090.3 1111.5 44459 .25 .30 3439.6 941 6 3706.2 1026.9 4107.7 1116.0 4464.0 .30 .85 srts'b 3455.6 945.7 3733.0 1031.3 41252 1120.5 44822 .35 .40 8679 3471.6 9499 3799.7 1035.7 4142.7 1125.1 4500.4 .40 .45 871.9 34S7.6 954.1 83165 1040.1 41603 1129.7 4518.7 ' .45 .50 8759 3503.7 953.3 8833.3 1044.4 4177.8 1134.3 4537.0 .50 .55 8799 8519.8 962.5 3850.2 1048.8 41954 1138.8 4555.4 .55 .60 SSl.O 3536.0 966. S 3867.1 1053.3 4213.0 1143.4 4578.8 .60 .65 S8S.O 3552.2 971.0 8384.1 1057.7 4230.7 11431 4592.3 .65 .70 892.1 85

3.5 126.8 507.8 162.1 643.4 .45 .50 70.4 281.8 97.3 8S9.2 12S5 513.9 164.0 655.9 .50 .55 71.7 2S6.8 98.7 895.0 130.2 520.7 1659 663.5 .55 .GO 72.9 291.8 100.2 400.9 131.8 527.4 167.8 671.0 .GO .65 74.7 296.8 101.7 406.8 133.5 5342 169.7 678.7 .65 .TO 75.5 801.9 103.2 412.7 135.2 540.9 171.6 686.3 .TO .75 76.7 807.0 104.7 41S.7 136.9 5478 173.5 694.1 .75 .80 7S.1 812.2 106.2 424.7 138.7 554.7 175.5 701.9 .80 .85 79.3 817.5 107.7 430.8 140.4 561.7 177.4 709.7 .85 .90 S0.7 322.7 109.3 437.0 142.2 568.6 179.4 717.5 .90 .95 82.0 828.0 110.8 443.2 143.9 575.7 181.8 725.4 .95 9 feet. 10 feet. 11 feet. 13 feet. .OO 183.3 733.3 225.3 901.2 271.6 1086.4 822.2 1288.9 .00 .05 1S5.3 741.3 227.5 910.1 274.0 1090.2 8249 1299.5 .05 .10 137.3 749.4 229.7 9190 276.5 1105.9 327.5 1310.1 .10 .15 189.4 757.5 232.0 923.0 178.9 1115.8 830.2 1320.8 .15 .20 1914 765.6 234.2 936.9 281.4 1125.6 832.9 1331. 5 .20 .25 193.4 773.7 236.5 945.9 233.9 1135.5 835.6 1312.3 .25 .30 195.5 781.9 238.7 955.0 286.3 1145.4 83S 3 1353.0 .30 85 197.5 79u2 241.0 964.1 289.1 1155.4 340.9 1363.8 .85 .40 190.6 79S.4 243.3 9T3.2 2918 1165.3 843.7 1374.7 .40 .45 2017 806.8 245.6 9S2.5 293.8 1175.4 846.4 1385.7 .45 5O 203.8 815.1 247.9 ! 991.7 296.4 1185.5 849.2 1396.6 .50 55 205.9 823.6 250.2 1001.0 299.0 1195.9 351.9 1407.7 55 ! .6T 20S.O 832 252.6 1010.3 301.6 1206.3 854.7 1418.7 .60 .65 210.0 8-10.0 254.9 1019.7 804.1 1216.3 857.4 1429.8 .65 .TO 2123 8490 257.3 1029.1 306.6 1226.3 860.2 1440.9 .TO .75 214.4 857.7 259.6 1038.5 309.2 1-236.7 863.0 1452.1 .75 .80 216.6 866.3 262.0 1043.0 311.8 1247.0 365.8 1463.3 .80 .85 218 7 8750 264.4 1057.5 314.3 1257.4 868.6 1474.6 .85 .90 220.9 883.7 266.8 1007.1 817.0 1-267.8 871.5 1485.9 ,9O .95 223.1 892.5 269.2 1076.8 819.6 1278.8 874.3 1497.8 .95 EMBANKIXG LAXDS FKOM KIVER-FLOODS. 159 TABLE HI. (Continued. ) on top and 7 feet wide at base for every foot high. Decimals of a foot. End 4 times middle End areas. 4 times middle End areas. 4 times middle End areas. 4 times middle Decimals ot a foot. .OO 13 877.2 feet 1508.6 14 486.4 feet. 1745.7 15 500.0 feet. 2000.0 16 568.0 feet. 2272.1 .00 .05 3SO.O 1520.1 439.5 175S.O 603.3 2013.2 571.5 22S5.9 .05 .10 3S2.9 1531.6 442.6 17703 506.6 2026.4 574.9 2299.7 .10 .15 |i 8<5.S 1543.2 445.7 1782.8 509.9 20397 578.4 2313 8 .15 .20 8S8.7 1554.7 448.8 1795.2 513.2 2052.9 5820 2328.0 .20 .25 391.6 1566.3 451.9 1807. 7 516.6 2066.3 5856 2342.8 .25 .30 394.5 1577.9 455.0 1S20.2 519.9 2079.7 5S9.2 2356.7 .30 .85 897.4 15S9.7 458.2 18328 5233 2093.2 592.7 2370.9 .85 .40 40<>.8 1601.4 461.3 1845.3 526.6 2106.6 596.3 23S5.1 .40 .45 4(13.8 1618.2 4645 1858.0 530.0 2120.1 599.9 2399.5 .45 .50 406.3 1625.0 467.7 1S70.7 5.33.4 2133.6 603.5 2413.9 .50 .65 409.2 1636.9 470.9 1883.5 5368 2147.3 607.1 2428.4 .55 .60 ' 412.2 1648.8 474.1 ] 896.3 540.2 2160.9 6107 2442.9 .60 .65 ,1 415.2 1660.8 477.3 1909.1 543.6 2174.6 614.4 2457.5 .65 .70 418.2 1672.8 4S0.5 1921.9 547.1 2188.3 6180 2472.0 .70 .75 1 421.2 1684.8 433.7 1934.8 550.5 2202.1 621.7 2486.7 .75 .80 i 424.2 1696.9 486.9 1947.8 554.0 22159 625.8 2501.8 .80 .85 I! 427.2 1709.0 490.2 1960.8 557.4 2229.8 629.0 2516.1 .85 .90 480.8 1721.2 498.4 1973.8 560.9 2243.7 632.7 2580.8 .90 .95 !! 433.4 1733.5 496.7 i 1986.9 564.5 22579 636.4 2545.7 .95 17 feat. 18 feet. 19 feet. feet. .OO 640.1 2560.5 716.7 2866.7 797.5 8190.1 882 7 8530.9 .00 .05 i 043. 8 2575.4 720.6 2SS2.5 801.7 3206.8 8S7.'l 35484 .05 .10 647.6 2590.3 724.6 2898.2 805.9 3223.4 891.5 35659 .10 .15 651.3 2605.3 728.5 2914.1 810.0 3240.2 895.9 8583.5 .15 .20 655.1 2620.8 732.5 2930.0 814.2 8256.9 900.3 3601.1 .20 .25 6. r >>.* 2635.4 786.5 2946.0 818.4 8273.fi 904.7 3618.8 .25 .30 662. 6 2650.5 740.5 2961.9 8'22.6 3290.4 909.1 363G.5 .30 .35 666.4 2665.7 744.5 2978.0 826.9 3307.8 913.6 36543 .85 .40 670.2 2680.9 748.5 2994,0 881.1 3324.4 918.0 8672.0 .40 .45 674.0 2696.2 752.5 3010.1 835.3 8341.3 9224 3689.8 .45 .50 677.9 2711.4 7566 3026.2 839.6 8358.3 926.9 3707.7 .50 .55 6S1.7 2726.8 760.6 3042.5 843.8 3375.4 9314 37257 .55 .GO (N5.5 2742.1 764.7 3058.7 8481 3392.5 935.9 3743.6 .60 .65 . 6MU 2757.6 T68.7 8075.0 852.4 3409.7 940.4 3761.7 .65 .70 693.8 2773.0 772.8 3091.8 856.7 8426.8 9449 87797 .70 .75 1 697.1 2788.6 776.9 31077 861.0 3444.0 949.4 3797.8 .75 .80 1 701.0 2804.1 781.0 3124.1 8653 34613 954.0 3S15.9 .80 .85 | 704.9 2819.7 7851 3140.6 869.7 3478.7 958.5 8S34.1 .85 .90 703.8 2835.3 789.0 8157.0 874.0 8496.1 963.1 8852.3 ,0 .95 || 712.7 2851.0 793.4 3173.6 878.4 8513.5 967.6 8870.6 .95 21 feet 22 feet. 23 feet. 24 feet. .OO 972.2 8888.9 1066.1 4264.2 1164.2 4656.8 1266.7 5066.7 .OO .05 97(5.9 3907.7 1070.9 4283.5 1169.2 4676.9 1271.9 5087.6 .05 .10 i 981.4 3925.6 1075.7 4302.7 1174.3 4697.0 1277.2 5108.6 .10 .15 1 986.0 3944.1 1080.5 4322.0 1179.3 4717.1 12824 5129.7 .15 .20 ! 990.6 3962.6 1085.3 4341.3 1184.3 47,37.4 12S7.7 5150.7 .20 .25 994.8 39S1.2 1090.2 4360.8 1189.4 4757.6 12929 5171.8 .25 .30 999.9 ; 8999.7 1095.0 4380.2 1194.5 4777.9 1298.3 5193.0 .3 > .85 M04.6 | 4018.3 1099.9 4399.7 1199.6 47983 1803.6 5214.8 .85 .40 1009.2 4036.9 11048 4419.2 1204.7 4818.7 1308.9 52:35.5 .40 .45 1018.9 4055.7 1109.7 4438.8 1209 8 4839.2 1314.2 5256.8 .45 .50 1018.6 4074.4 1114.6 4458.3 1214.9 4&59.6 1319.5 5278.1 .50 .55 1 02&8 4093.2 1119.5 4478.0 12200 48SO 1 1324.9 5299.5 .55 . .60 1028.0 4112.0 1124.4 4497.7 1225.2 4900.6 1830.2 5320.9 .ed .65 1082.7 4130.9 1129.4 4517.5 1230.3 4921.3 13356 5342.4 .65 .70 m.17.4 4149.8 1134.3 4537.2 12:35.5 4941.9 1341.0 5363.9 .70 1 .75 1042.2 41 68. 8 1139.2 4557.0 I 1240.6 4962.6 1346.4 5385.5 .75 .80 1040.9 4187.8 1144.2 4576.9 1245.8 4983.3 1351.8 5407.0 .SO ; .85 1051.7 420B.8 11492 4596.8 1251.0 5004.1 1357.1 5428.6 .86 .90 1H5C..5 4-225.9 1154.2 4616.8 1256.2 6024.0 1862.6 5450.2 .90 : .95 1061.2 4245.0 1159.2 4636.8 1261.4 5045.8 1368.0 5472.0 .95 160 PKINCIPLES AND PRACTICE OP AUXILIARY TO TABLE IV. WHEN THE AREAS CONTAIN DECIMAL PARTS. Decimal of Areas. Decimal Cubic Yards Corresponding. .00 .0 .17 .50 .3 .66 .4 .83 .5 ' 1.00 .6 N.B. When the square area consists of a whole number and of decimal parts of a whole number, the cubic yards corresponding to those decimal parts, as given in the subjoined Auxiliary Table, are to be added to the cubic yards corresponding to the whole number as set forth in Table IV. EMBANKING LANDS FROM KIVEK-FLOODS. 161 TABLE IV. Table of Cubic Yards corresponding to areas in square feet. 1 If J jjs ft is || | || J If i! ft W 9 9 573.4 8 613.0 7 652.5 1 692.0 2 495.1 6 534.5 93O 574.1 4 613.6 8 653.1 2 692.6 8 495.7 7 535.2 1 574.7 5 614.2 9 653.7 8 693.2 4 490.3 8 535.8 2 575.3 6 614.8 106O 654.3 4 5 496.9 9 5364 8 575.9 7 615.4 1 654.9 5 6944 6 497.5 87O 537.0 4 576.5 8 616.0 2 655.5 6 695.1 7 493.1 1 537.6 5 577. J 9 616.7 8 656.2 7 695.7 8 498.8 2 533.3 6 577.8 1000 617.3 4 656.8 t 696.8 9 499.4 3 5339 7 578.4 1 617.9 5 657.4 9 696.9 81U 500.0 4 539.5 8 579.0 2 618.5 6 653.0 ll?O 697.5 1 500.6 5 540.1 9 579.6 8 619.1 7 65S.6 1 698.1 2 501.2 6 5407 94O 5S0.2 619.8 8 659.3 2 698.8 3 501.8 7 5414 1 580.3 5 620 4 9 659.9 8 699.4 4 502.5 * 8 542.0 2 531.5 6 621.0 1O7O 660.5 1 700.0 5 503.1 9 542.6 3 532.1 7 621.6 1 661.1 5 700.6 6 503.7 88O 543.2 4 582.7 8 622.2 2 661.7 6 701.2 7 504.3 1 543.8 5 6S3.3 9 622.8 8 662 8 7 701.8 8 504.9 2 544.4 6 583.9 1O1O 623.5 4 663.0 8 702.5 9 505.5 8 545.1 7 5s4.5 1 624.1 5 663.6 9 703.1 82O 506.2 4 545.7 8 585.2 2 624.7 6 664.2 114O 703.7 1 506.8 5 5463 9 585.8 8 625.3 7 664.8 1 704.3 2 507.4 6 546.9 950 586.4 4 625.9 8 665.4 2 704.9 8 503.0 7 547.5 1 587.0 5 626.5 9 666.0 8 7055 4 508.6 8 543.1 2 537.6 6 627.2 180O 666.7 4 706.2 5 509.2 9 5488 3 588.3 7 627.8 1 667.3 5 706.8 6 509.9 89O 549.4 4 5S3.9 8 628.4 2 667.9 6 707.4 7 510.5 1 550.0 5 539.5 9 629.0 8 668.5 7 708.0 8 511.1 2 5506 6 590.1 102O 629.6 4 669.1 703.6 9 511.7 3 5512 7 5907 1 630.2 5 669.8 9 709.3 83<> 512.3 4 651.8 8 591.4 2 630.9 6 670.4 I ISO 709.9 1 513.0 5 552.5 9 592.0 8 631.5 7 671.0 1 710.5 2 513.6 6 553.1 96O 592.6 4 632.1 8 6T1.6 2 711.1 166 PRINCIPLES AND PRACTICE OF AUXILIARY TO TABLE IV. WHEN THE AREAS CONTAIN DECIMAL PARTS. Decimal of Areas. Decimal Cubic Yards Corresponding. .00 .0 .IT .1 .33 .2 .50 .3 .66 .4 .83 .6 1.00 .6 N.B. When the square area consists of a whole number and of decimal parts of a whole number, the cubic yards corresponding to those decimal parts, as given in the subjoined Auxiliary Table, are to be added to the cubic yards corresponding to the whole number as set forth in Table IV. EMBANKING LANDS FKOM BIVEB-FLOODS. 167 TABLE IV. (Continued.) Table of Cubic Yards corresponding to Areas in square feet. Areas in square feet. Cubic yards corresponding. Areas in square feet. If 12 U 8 1 |s a Cubic yards corresponding. Areas in square feet. Cubic yards I corresponding. Areas in square feet. Cubic yards corresponding. Areas in square feet. Cubic yards corresponding. 8 711.7 7 751.2 1 790.7 6 830.2 9 869.8 8 909.8 4 712.3 8 751.8 2 791.4 6 830.9 1410 870-4 4 909.9 5 713.0 9 752.5 8 792.0 7 631.5 1 871-0 5 910.5 6 718.6 122O 753.1 4 792.6 8 882.1 2 871-6 6 911.1 7 714.2 1 758.7 5 793.2 9 882.7 3 872-2 7 911.7 8 714.8 2 754.8 6 793.8 1350 883.3 4 872-8 8 912.8 9 715.4 8 754.9 7 794.4 1 833.9 5 878-5 9 913.0 116O 716.0 4 755.5 8 795.1 2 834.6 6 874-1 148O 913.6 1 716.7 5 756.2 9 795.7 8 835.2 7 874-7 1 914.2 2 717.3 6 756.8 1290 796.8 4 885.8 8 875-8 2 914.8 8 717.9 7 757.4 1 796.9 5 886.4 9 875-9 8 915.4 4 718.5 8 758.0 2 797.5 6 837.0 142O 876-5 4 916.0 6 719.1 9 758.6 8 798.1 7 837.7 1 877-2 5 916.7 6 719.8 123O 759.3 4 798.8 8 838.8 2 877-8 6 917.8 7 720.4 1 759.9 5 799.4 9 83S.9 8 878-4 7 917.9 8 721.0 2 760.5 6 800.0 1360 839.5 4 879-0 8 918.5 9 721.6 3 761.1 7 800.6 1 840.1 6 879-6 9 919.1 1170 722.2 4 761.7 8 801.2 2 840.7 6 880-2 1490 919.8 1 722.8 5 762.3 9 801.8 8 841.4 7 8SO-9 1 920.4 2 723.5 6 763.0 13OO 802.5 4 842.0 8 881-5 2 921.0 8 724.1 7 763.6 1 808.1 5 842.6 9 882-1 8 921.6 4 724.7 8 764.2 2 803.7 6 843.2 1430 882-7 4 922.2 5 725.3 9 764.8 8 804.8 7 843.8 1 883-3 5 922.8 6 725.9 124O 765.4 4 804.9 8 844.4 2 888-9 6 923.5 7 726.5 1 766.0 5 805.5 9 845.1 3 884-6 7 924.1 8 72T.2 2 766.7 6 806.2 137O 845.7 4 885-2 8 924.7 9 727.8 8 767.3 7 806.8 1 846.3 5 885-8 9 925.8 118O 728.4 4 767.9 8 807.4 2 846.9 6 886-4 150O 925.9 1 729.0 5 768.5 9 808.0 8 847.5 7 887-0 1 926.5 2 729.6 6 769.1 1310 808.6 4 848.1 8 887-7 2 927:2 8 730.2 7 769.8 1 809.8 5 848.8 9 8 927.8 4 730.9 8 770.4 2 809.9 6 849.4 1440 888-9 4 928.4 5 731.5 9 771.0 8 810.5 r 850.0 1 889-5 5 929.0 6 732.1 125O 771.6 4 811.1 8 850.6 2 890-1 6 929.6 7 782.7 1 772.2 6 811.7 9 851.2 8 890-7 7 980.2 8 733.3 2 772.8 6 812.3 138O 851.8 4 891-4 8 980.9 9 733.9 8 773.5 7 813.0 1 852.5 5 892-0 9 931.5 1190 734.6 4 774.1 8 818.6 2 858.1 6 892-6 510 932.1 1 735.2 5 774.7 9 814.2 3 853.7 7 898-2 1 932.7 2 735.8 6 775.3 1320 814.8 4 854.3 8 893-8 2 933.3 8 736.4 7 775.9 1 815.4 5 854.9 9 894-4 8 983.9 4 737.0 8 776.5 2 816.0 6 855:5 145O 895-1 4 934.6 5 737.7 9 777.2 3 816.7 7 856.2 1 895-7 5 935.2 6 738.8 126O 777.8 4 817.3 8 856.8 2 896-3 6 935.8 7 738.9 1 778.4 5 817.9 9 857.4 8 896-9 7 986.4 8 739.5 2 779.0 6 818.5 139O 858.0 4 897-5 8 937.0 9 740.1 8 779.6 7 819.1 1 858.6 5 898-1 9 937.7 120O 740.7 4 780.2 8 819.8 2 859.3 6 898-8 52O 938.3 1 741.4 5 780.9 9 820.4 3 859.9 7 899-4 1 938.9 2 742.0 6 781.5 1330 821.0 4 860.5 8 900-0 2 939.5 8 742.6 7 782.1 1 821.6 5 861.1 9 900-6 3 940.1 4 743.2 8 7827 2 822.2 6 861.7 46O 901-2 4 940.7 5 748.8 9 783.3 8 822.8 7 862.3 1 901-8 5 941.4 6 744.4 1270 783.9 4 823.5 8 863.0 2 902-5 6 942.0 7 745.1 1 784.6 5 824.1 9 868.6 3 908-1 7 942.6 8 745.7 2 785.2 6 824.7 1400 864.2 4 908-7 8 943.2 9 746.3 8 785.8 7 825.3 1 864.8 5 904-8 9 943.8 112O 746.9 4 786.4 8 825.9 2 865.4 6 904-9 53O 944.4 1 747.5 5 787.0 9 826.5 8 866.0 7 905.5 1 945.1 2 74S.1 6 787.7 1340 827.2 4 866.7 8 906.2 2 945.7 8 74S.8 7 788.8 1 827.8 5 867.3 9 906.8 8 946.3 4 749.4 8 Tss.y 2 828.4 6 867.9 47O 907.4 4 946.9 6 750.0 9 789.5 3 829.0 7 868.5 1 908.0 5 947.5 6 750.6 1280 790.1 4 829.6 8 869.1 2 008.6 6 948.1 168 PRINCIPLES AND PRACTICE OF AUXILIARY TO TABLE IV. WHEN THE AREAS CONTAIN DECIMAL PARTS. Decimal of Areas. Decimal Cubic Yards Corresponding. .00 .0 .17 .1 .33 .2 .66 .4 .83 .5 1.00 .6 N.B. When the square area consists of a whole number and of decimal parts of a whole number, the cubic yards corresponding to those decimal parts, as given in the subjoined Auxiliary Table, are to be added to the cubic yards corresponding to the whole number as set forth in Table IV. EMBANKING LANDS FKOM KIVEK-FLOODS. 169 TABLE IV. (Continued.-) Table of Cubic Yards corresponding to Areas in square feet. 1 1 5 Cubic yards correspouding. In square feet. || S| 4 Cubic yards corresponding. JS Cubic yards correspouding. i Cubic yards correspouding. 7 948.8 1 988.3 5 1027.8 9 1067.3 8 1106.8 i 1146.8 8 949.4 2 988.9 6 1023.4 1730 1067.9 4 1107.4 8 1146.9 9 950.0 8 9S9.5 7 1029.0 1 1068.9 5 1108.0 9 1147.5 1540 950.6 4 990.1 8 1029.6 2 1069.1 6 1108.6 1860 1148.1 1 951.2 5 990.7 9 1030.2 8 1069.8 7 1109.3 1 1148.8 2 951.8 6 991.4 167O 1030.9 4 1070.4 8 1109.9 2 1149.4 3 952.5 7 992.0 1 1031.5 5 1071-0 9 1110-5 3 1150.0 4 953.1 8 9926 2 1032.1 6 1071.6 180O 1111.1 4 1150.6 5 953.7 9 993.2 8 1032.7 7 1072.2 1 1111.7 5 1151.2 6 954.3 161O 993.8 4 1033.3 8 1072.8 2 1112.3 6 1151.8 7 954.9 1 994.4 5 1033.9 9 1073.5 8 1118.0 7 1152.5 8 955.5 2 995.1 6 1034.6 174O 1074.1 4 1118.6 8 1153.1 9 956.2 S 995.7 7 1035.2 1 1074.7 5 1114.2 9 1153.7 155O 956.8 4 996.3 8 1035.8 2 1075.8 6 1114.8 1870 1154.3 1 957.4 5 996.9 9 1036.4 8 1075.9 7 1115.4 1 1154.9 2 953.0 6 997.5 168O 1037.0 4 1076.5 8 1116.0 2 1155.5 3 958.6 7 998.1 1 1037.7 5 1077.2 9 1116.7 3 1156.2 4 959.3 8 2 1038.3 6 1077.8 181O 1117.8 4 1156.8 5 959.9 9 999^4 3 1033.9 7 1078.4 1 1117.9 5 1157.4 6 960.5 1G20 1000.0 4 1039.5 8 1079.0 1118.5 6 1158.0 7 961.1 1 1000.6 5 1040.1 9 1079.6 8 1119.1 7 1158.6 961.7 2 1001.2 6 1040-7 1750 1030.2 4 1119.8 8 1159.8 9 962.3 3 1001.8 7 1041-4 1 10S0.9 5 1120.4 9 1159.9 15GO 968.0 4 1002.5 8 1042-0 2 1031-5 6 1121.0 1880 1100.5 1 963.6 5 1003.1 9 1042-6 3 1032.1 7 1121.6 1 1161.1 2 964.2 6 1003.7 169O 1043-2 4 1082.7 . 8 1122.2 1161.7 3 964.8 7 1004.3 1 1043-8 5 1033-3 9 1122.8 8 1162.8 4 965.4 8 1004.9 2 1044-4 6 10S3.9 1820 1123.5 4 1163.0 5 966.0 9 1005.5 3 1045-1 7 10S4.6 l 1124.1 5 1163.6 6 9667 163O 1006.2 4 1045-7 8 1085.2 2 1124.7 6 1164.2 7 967.3 1 1006.8 5 1046-8 9 1035-8 8 1125.3 7 1164.8 8 967.9 2 1007.4 6 1046-9 176O 1086.4 4 1125.9 8 1165.4 9 968.5 8 1008.0 7 1047-5 1 1087.0 5 1126.5 9 1166.0 157O 969.1 4 1003.6 8 1048-1 2 1087-7 6 1127.2 1890 1166.7 1 969,8 5 1009.3 9 1048-8 8 10S8.3 7 1127-8 1 1167.3 2 970.4 6 1009.9 1700 1049-4 4 10S8.9 8 1128.4 2 1167.9 8 971.0 7 1010.5 1 1050-0 5 1089.5 9 1129.0 8 1168.5 4 971.6 8 1011.1 2 1050-6 6 1090.1 183O 1129.6 4 1169.1 5 972.2 9 1011.7 3 1051-2 7 1090.7 1 1130.2 5 1169.8 6 972.8 1640 1012.3 4 1051-8 8 1091.4 2 1130.9 6 1170.4 7 978.5 1 1013.0 5 1052-5 9 1092.0 8 1131.5 7 1171.0 8 974.1 2 1013.6 6 1053-1 177O 1092.6 4 1132.1 8 1171.6 9 974.7 3 1014.2 7 1053-7 1 1093.2 5 1132.7 9 1172.2 158O 975.3 4 1014.8 8 1054-3 2 1093.8 6 1133.8 190O 1172.8 1 975.9 5 1015.4 9 1054-9 8 1094.4 7 1133.9 1 1173.5 2 976.5 6 1016.0 1710 1055-5 4 1095.1 8 1184.6 2 1174.1 3 977.2 7 1016.7 1 1056-2 5 1095.7 9 1135.2 8 1174.7 4 977.8 8 1017.8 2 1056-8 6 1096.3 1S1O 1135.8 4 1175.3 5 973.4 9 1017.9 8 1057-4 7 1096.9 1 1136.4 5 1175.9 6 979.0 165O 1018.5 4 1053-0 8 1097.5 2 1137.0 6 1176.5 7 979.6 1 1019.1 5 1058-6 9 1098.1 8 1137.7 7 1177.2 8 980.2 2 1019.8 6 1059-3 178O 1098.8 4 1188.3 8 1177.8 9 930.9 8 1020.4 7 1059-9 1 1099.4 5 1188.9 9 1178.4 1590 981.5 4 1021.0 8 1060-5 2 1100.0 6 1139.5 1910 1179.0 1 982.1 5 1021.6 9 1061.1 3 1100.6 7 1140.1 1 1179.6 2 9S2.7 6 1022.2 1720 1061.7 4 1101-2 8 1140.7 2 1180.2 8 933.3 7 1022.8 1 1062-3 5 1101-8 9 1141.4 3 1180.9 4 933.9 8 1023.5 2 1063.0 6 1102.5 185O 1142.0 4 1181.5 5 984.6 9 1024.1 8 10t)3.6 7 1103.1 1 1142.6 5 1182.1 6 985.2 166O 1024.7 4 1064.2 8 1103.7 2 1148.2 6 1182.7 7 935.8 1 1025.3 5 1064.8 9 1104.3 8 1143.8 7 1188.8 8 936.4 2 1025.9 6 1065.4 179O 1104.9 4 1144.4 8 11 S3. 9 9 937.0 3 1026.5 7 1066.1 1105.5 5 1145.1 9 1184.6 160O 987.7 4 1027.2 8 1066.T 2 1106.2 6 1145.7 192O 1185.2 170 PBINCIPLES AND PRACTICE OF AUXILIARY TO TABLE IV. WHEN THE AREAS CONTAIN DECIMAL PARTS. Decimal of Areas. Decimal Cubic Yards Corresponding. .00 .0 .17 .1 .60 .3 .66 .4 .83 .5 1.00 .6 N.B. When the square area consists of a whole number and of decimal parts of a whole number, the cubic yards corresponding to those decimal parts, as given in the subjoined Auxiliary Table, are to be added to the cubic yards corresponding to the whole number as set forth in Table IV. EMBANKING LANDS FROM RIVER-FLOODS. TABLE IV< (Continued.) Table of Cubic Yards corresponding to Areas in square feet. 1 is i ^ Cubic yards corresponding. J s| *l if It ^S Areas in square feet. Cubic yards corresponding. li 3 Cubic yards corresponding. !i Cubic yards corresponding. i J |j Cubic yards corresponding. i 1185.8 2 1217.3 ! 1248. i 1280. 1811. g 1848.2 2 1186.4 8 1217.9 i 1249. { 1280. | 1812. ' 1848.8 8 1187.0 4 1218.5 5 1250. ^ 1281. > { 1818. 1844.4 4 1187.T 5 1219.1 6 1250. f ( 1282. 8 1818. | 1845.1 5 1188.3 6 1219.8 \ 1251.2 8 1282. < 1314. 218< 1845.7 6 1188.9 7 1220.4 8 1251.8 9 1283.8 213< 1314, 1846.3 7 11S9.5 8 1221.0 9 1252.5 208O 1283. 1315.4 f 1346.9 8 1190.1 9 1221.6 2030 1253.1 1 1284.6 5 1316.0 1 1347.5 9 1190.7 198O 1222.2 1 1253.7 2 1285.2 8 1316.7 4 1348.1 193O 1191.4 1 1222.8 2 1254.8 3 1285.8 4 1817.8 5 1848.8 1 1192.0 2 1223.5 8 1254.9 4 1286.4 5 1317.9 6 1849.4 2 1192.6 8 1224.1 4 1255.6 5 1287.0 6 1818.5 7 1350.0 3 1193.2 4 1224.7 5 1256.2 6 1287.7 7 1819.1 8 1350.6 4 1193.8 6 1225.8 6 1256.8 7 1288.8 8 1319.8 9 1351.2 6 1194.4 6 1225.9 7 1257.4 8 1288.9 9 1320.4 219O 1351.8 6 1195.1 7 1226.5 8 1258.0 9 1289.5 2I4O 1321.0 1 1352.5 T 1195.7 8 1227.2 9 1258.6 2090 1290.1 1 1321.6 2 1353.1 8 1196.3 9 1227.8 204 O 1259.3 1 1290.7 2 1822.2 8 1353.7 9 1196.9 1990 1228.4 1 1259.9 2 1291.4 3 1822. J 4 1354.3 194O 1197.5 1 1229.0 2 1260.5 8 1292.0 4 5 1354.9 1 1198.1 2 1229.6 3 1261.1 4 1292.6 5 I824.'l 6 1355.6 2 1198.8 8 1230.2 4 1261.7 5 1293.2 6 1324.7 7 1856.2 8 1199.4 4 1280.9 5 1262.3 6 293.8 7 1825.8 8 1856.8 4 1200.0 5 1281.5 6 1268.0 7 294.4 8 1825.9 9 1857.4 5 1200.6 6 1232.1 7 1263.6 8 295.1 9 1826.5 220O 1358.0 6 1201.2 7 1232.7 8 1264.2 9 295.7 215O 1327.2 1 358.6 7 1201.8 8 123? .8 9 1264.8 too 296.8 1 327.8 2 859.3 8 1202.5 9 1233.9 205O 1265.4 1 296.9 2 828.4 3 359.9 9 1203.1 1234.6 1 266.0 2 297.5 8 829.0 4 860.5 1950 1203.7 1 1235.2 2 266.7 8 298.1 4 829.6 5 861.1 1 1204.3 2 1235.8 8 267.8 4 298.8 5 830.2 6 861.7 1 2 1204.9 3 236.4 4 267.9 6 299.4 6 330.9 7 362.3 8 1205.6 4 237.0 5 268 5 6 300.0 7 831.5 8 868.0 4 1200.2 5 237.7 6 269.'l 7 300.6 8 832.1 9 368.6 5 1206.8 6 123S.8 7 269.8 8 801.2 9 832.7 21O 364.2 6 1207.4 7 238. 9 8 270.4 9 801.8 160 883.3 1 364.8 T 1208.0 8 239.5 9 271.0 110 802.5 1 883.9 2 365.4 8 1208.6 9 240.1 oco 271.6 1 303.1 2 834.6 8 866.0 9 1209.3 01O 240.7 1 272.2 2 303.7 3 835.2 4 866.7 I960 209.9 1 241.4 2 272.8 3 804.8 4 835.8 5 367.3 1 210.5 2 242.0 3 -'73..-> 4 804.9 5 836.4 6 367.9 2 211.1 8 -ML-.*; 4 2741 6 805.6 6 337.0 7 868.5 8 211.7 4 243.2 5 274.7 6 306.2 7 387.7 8 369.1 4 212.3 5 -'4:5. s 6 275.3 7 806.8 8 838.3 9 869.8 5 213.0 6 244.4 7 275.9 8 807.4 9 838.9 22O 870.4 6 213.6 7 245.1 8 276.5 9 308.0 17O 889.5 1 371.0 T 214.2 8 245.7 9 277.2 120 308.6 1 840.1 2 871.6 8 214.8 9 2-ilLS 07O 277.8 1 309.8 2 840.7 8 372.2 9 215.4 020 246.9 1 278.4 2 809.9 8 341.4 4 372.8 197O 216.0 1 247.9 2 279.0 8 810.5 4 842.0 5 378.5 1 216.7 2 248.1 8 279.6 4 811.1 5 842.6 6 874.1 D. 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