LETTER OF TRANSMITTAL.

MISSOURI RIVER COMMISSION,

Saint Louis, Mo., February 23, 1888.

SIR: I have the honor to forward herewith the report of the Board of Engineer Officers convened by Special Orders, No. 1, Headquarters Corps of Engineers, dated Washington, D. C., January 10, 1888.

Very respectfully, your obedient servant,

CHAS. R. SUTER, Lieut. Col. of Engineers.

The CHIEF OF ENGINEERS, U. S. A.

REPORT OF BOARD OF ENGINEERS.

SAINT LOUIS, Mo., February 23, 1888. SIR: The Board of Engineer Officers convened by "Special Orders, No. 1," dated "Headquarters Corps of Engineers, United States Army, Washington, D. C., January 10, 1888," to consider and report upon Senate bill No. 275, Fiftieth Congress, first session, met in this city on January 16, 1888, and remained in session till and including January 21. They then adjourned to allow of the collection of further information. The Board met again on the 27th of January and remained in session till and including January 30, when they adjourned sine die. During this time the Board have gone very carefully over the bill submitted to them for consideration, and have sought from all available sources information to guide them in their final conclusions. The bill under consideration was prepared, in essentially its present shape, in 1882, and during the period which has elapsed since that date much information and experience have been obtained, not then available, and a good deal of general and special legislation bearing on the general subject has been enacted. The Board have felt that in a general bill, affecting such wide-spread and important interests as the one under consideration, all such matter as experience has shown to be of value should be included. They have, therefore, felt it their duty to recommend many changes in the bill and also to recommend new sections covering points of importance not embraced in the original draught.

The great majority of these changes, at least in the sections noted as "general," are based upon recent general or special laws affecting bridges, notably the general law for bridges over the Ohio River. In all other cases the changes recommended are such as experience has shown to be desirable or necessary. The number of changes and additions recommended has been so great that the Board have rewritten the entire bill, and recommend the inclosed copy as a substitute for the original. In order that the whole matter may be clearly understood, the changes recommended will be noted and explained, section by section, the numbers given referring to the modified bill.

In title. The upper limit on the Mississippi River, designated as the "port of Saint Paul, in the State of Minnesota," is changed to "mouth of Minnesota River, in the State of Minnesota." This gives a more definite limit and includes the Government landing at Fort Snelling, about 4 miles above the steamboat landing at Saint Paul. It is not thought that this extends the limit beyond the port of Saint Paul, and in any case, the 4 miles of river referred to are as navigable in their

natural condition, and as susceptible of improvement, as many portions of the river below Saint Paul.

"Across the Illinois River, between its mouth and La Salle, in the State of Illinois," is changed to "across the Illinois and Des Plaines rivers, between the mouth of the Illinois and the city of Joliet, in the State of Illinois." The present project for the improvement of the Illinois River, upon which the United States Government and the State of Illinois have for many years been engaged, contemplates a system of slackwater navigation with locks 350 feet by 75 feet, as high up as Joliet, thence by canal along the most feasible route yet to be determined on to Lake Michigan. The requirements for navigation will, therefore, be the same from La Salle to Joliet as for the other portions of the Illinois River.

In this connection the Board desires to call attention to the fact that the upper limit for the application of this bill on the Missouri River is fixed at the mouth of the Dakota or James River, in Dakota, and near the town of Yankton, while the lower limit on the Mississippi is fixed at the port of Natchez, Miss. The reason for selecting these limits is not apparent. So far as the Missouri River is concerned there is no change of importance in its physical characteristics until the rocky portion of the stream above Fort Carroll is reached, and the Board are decidedly of the opinion that the provisions laid down for that portion of the stream above the mouth of the Platte should be made applicable as far up as Fort Benton, the head of navigation. With regard to the southern limit on the Mississippi, the Board consider that there is no physical change in the stream of consequence until after Red River is passed, and that the conditions governing bridge construction for the Lower Mississippi would not need modification, at least as far down as Baton Rouge, where the bluffs end, possibly not until New Orleans is reached and ocean shipping met with. Here it is possible that some modification might be necessary or desirable.

Section 1.-In this section has been added, "when public necessity so demands." The Board consider that all bridges, no matter how care. fully located or planned, are more or less obstructions to navigation and while it is doubtless proper that the latter interest should give way to a certain extent when a bridge is a public necessity, yet it does not seem right that this hardship should be imposed unless the general interests imperatively require it. This consideration is of especial importance in case of the duplication of bridges at any locality. It is a known fact that in several cases the construction of bridges has been contemplated where such construction was not a public necessity, and where the additional obstruction to the interests of navigation would have been serious, without any compensating advantage to the general public.

There has also been added, "at points where said construction will not materially affect the interests of navigation." This clause is found in all the recent bridge acts for the Upper Mississippi River, and is an important one. There are some points where the construction of a bridge would be almost a bar to successful navigation, whereas at other points in the vicinity a bridge would not be so serious an obstruction as to prohibit its construction. In such cases it seems proper that the authority to construct shall only apply to the localities where regard for the navigation interest will best justify the construction. An addition has also been made to the description of the portions of the rivers over which the authority under the bill extends by repeating the limits as given in the title of the bill.

Another addition is as follows, viz, "and hereafter no bridges shall be built over said rivers within said limits, except under said provisions and requirements." Heretofore a number of bridges within the limits contemplated by this act have been erected without the authority of Congress, and no law exists for the prevention of such construction. Many of these bridges have proved serious obstructions to navigation. As the object of the present act is to prevent the unnecessary obstruction of navigation by bridges improperly located or constructed, it would seem proper that such unnecessary obstruction be prevented by pro hibiting the construction of all bridges which do not conform to the requirements of this act. Without this requirement it would result that those who obtain authority for their action will be subject to more restrictions than those who do not, and the act will be practically valueless.

Section 2.-Only such changes are made here as were necessary to make the numbers correspond to the sections of the bill as amended by the Board.

Section 3. Some few changes have been made in the definitions of terms of frequent occurrence in the bill, which were considered neces sary for a better understanding of the ideas they were intended to express, or where it was thought the language used might give rise to misunderstanding or controversy. Throughout the bill, as now submitted, many changes have been made in the wording in order to have the phraseology correspond with the definitions given in this section.

Section 4.-This section is section 7 of the original bill. The principal change to be noted is that the provision requiring through-spans is left out, as being unnecessary and sufficiently covered by other provisions in the bill.

Section 5 in the original bill is omitted as unnecessary, as the Board consider draw-spans in high bridges undesirable and generally impracticable. This subject is fully discussed in the special sections where it occurs.

Section 5.-This section is section 6 of the original bill. The principal change to be noted is that the Board have attempted to do away with the idea of prescribing how the opening or openings through low bridges shall be made. It is sufficient for navigation purposes to know that an opening or openings of the prescribed width will be available when required for the passage of river craft, and the method of effecting such openings should be left, as far as possible, to the judgment of the builders of the bridge, subject to the revision provided for in this act.

The amended section also requires that draw-openings shall be visible for a distance of not less than one mile above the bridge. Safety requires that descending boats or other craft should be able to know certainly whether the draw is open or shut a sufficient time before reaching it, to admit of stopping or landing, should either be necessary. It also requires that so far as practicable, and when in the interests of navigation, all bridges should be located above important landings. The reason for this lies in the fact that, with a bridge located just below a landing, boats coming to or leaving the same would be in great danger of being injured.

It is further provided, that in certain cases where river craft might obstruct the passage through or under the bridge by landing in too close proximity thereto, the right to do so should be extinguished by the owners of the bridge. This provision occurs in the general bridge law for the Ohio River, and seems to the Board a proper one to intro

duce here. The additional draws provided for in the bill to accomplish this object would probably be much more expensive and generally im practicable.

Section 6.-In line 11, section 6, of the original bill, for "bridge" has been substituted "span or spans," as there can be no objection to the movement of trains over any portion of the bridge other than the drawopening. Lines 12 and 13, "or of boats through said draw," is omitted as unnecessary, such delay being considered of extremely improbable occurrence. The rest of the section is unchanged.

Section 7.-This is section 8 of original bill. An additional requirement is introduced to the effect that the axis of the bridge shall be as nearly as may be at right angles to the current. This is deemed important, to prevent the construction of bridges very oblique to the direction of the current, which are not considered safe for navigation. The prohibition of riprap in channel or draw spans is extended to all spans, as experience has shown that its use is never necessary, except as a remedy for improper construction, and its presence always affects the waterway and may unduly increase the velocity of the current at the site of the bridge. This section also requires the removal of this and all other obstructions, under the Secretary of War's direction, by and at the expense of the company or persons owning, controlling, or operating the bridge.

Section 8.-This is a new section intended to regulate the character of the approaches and other parts of the bridge with especial reference to their bearing on the flood discharge of the river.

Section 9.-Is new and covers the case of any bridge erected in the near vicinity of an existing bridge. In this case, if the general requirements were strictly followed, there might result a very serious obstruction to navigation.

Section 10.-This is section 9 of the original bill somewhat amended and enlarged, so as to require the building and maintenance of all such accessory works as may be necessary to overcome, to as great a degree as possible, the obstruction to navigation caused by the construction of bridges. In its present shape the section conforms more closely to existing laws on the subject which it covers.

Sections 11, 12 and 13.-These sections replace numbers 10 and 11 of the original bill. The divisions introduced are the mouths of the Kaw and Platte rivers, instead of the Union Pacific Bridge at Omaha. At the points mentioned the influx of large tributaries modifies very materially the size and volume of the river, and will undoubtedly in the future affect considerably the character of its navigation. Above the Platte River the clear channel-way called for is as small as is considered compatible with the free discharge of the river at high stages, and the height is the same as is required by all recent bridge acts. Between the Platte and the Kaw there is an additional requirement of at least one channel-span of not less than 400 feet clear water-way, the height remaining as above. Below the Kaw all spans are to give at least 400 feet clear channel-way, owing to the much greater volume and commercial importance of the river, and the required height is increased 5 feet as the detentions at high stages, due to insufficient height, will be longer, more frequent, and more injurious to navigation than above the Kaw. The lengths of span called for are moderate; in fact, they have been adopted voluntarily in nearly all of the ten bridges which have been built since 1874, owing, it is said, to the saving in cost effected by reducing the number of piers with their costly and difficult foundations.

The Board have omittea the provisions for draw-bridges, as they consider that such structures, dangerous and undesirable in all cases, are entirely inadmissible on the Missouri, where the shifting channels and fierce current require that all possible precautions be taken to prevent bridges from becoming an absolute bar to navigation. This view has been consistently held and urged by the officers in charge of the improvement of this river, and also by the Missouri River Commission. The Board holds that all spans over the water-way should be available for the passage of boats when necessary or desirable, and that these spans should be as long as possible, both for the safety of navigation and for the free discharge of the river at high stages. These conditions can not be complied with in a low bridge. Out of seventeen, the tota1 number of bridges, either built or building over the Missouri, but fou are low bridges, and all these were constructed prior to 1875. All four are difficult and dangerous of passage, two in fact being well-nigh impassable at high stages, while at the two others navigation has been several times entirely suspended, owing to the shifting of the channel from under the draw-spans at low water. Since their construction, ten other bridges have been built, all high, although the alternative of a low bridge was allowed. The motive for this is said to have been economy. It would seem, therefore, altogether unjustifiable to authorize a class of bridges, which, if built, would be a constant menace to navigation and which seem to be rarely demanded even on the score of economy.

Section 14.-This section is a substitute for numbers 12, 13, and 18 of the original bill. The general character of the boats to be accommodated on the Mississippi River above the mouth of the Missouri and on the Illinois River is essentially the same, and the requirements for safe navigation would seem to be about identical. The clear headway required of 55 feet is such as is given by existing high bridges over the Upper Mississippi and is the least height that will accommodate the interests of navigation. The height of pilot houses and other portions of Upper Mississippi steamers have already been reduced to conform to present conditions, and further reduction is impracticable. In many of the bridges over the Upper Mississippi draw-openings of 160 feet and channel or raft spans of 250 feet are provided, but as each bridge furnishes its individual share of obstruction, dimensions heretofore used should not be taken as a guide for future construction. With a view to reducing the expenses of navigation to a minimum, and also owing to the fact that the improvement of navigation has made it possible, the size of rafts has been materially increased of late, and existing bridges are found to be much greater obstructions and to cause more delay and expense than formerly. As the advance in the science of bridge building renders the construction of draw-spans with 200 feet openings and other spans of 350 feet length simple matters, it is thought that the increased dimensions suggested are quite reasonable, and are the least that will properly accommodate present and prospective river traffic.

The section also permits the construction of such inclined highway bridges as are now in successful use at Dubuque and Saint Paul, and which will doubtless be desired elsewhere in the near future. The orig inal sections did not permit their construction.

Provision is also made for all cases in which a narrow river, or other causes, may permit a reduction of the requirements without injuring the interests of navigation.

For the Illinois River, where the difficulties of navigation are not so great and where the rafting interest has not to be considered, draw openings of 160 feet are permitted.