information as can be obtained of special cases like those that have been noted as requiring further explanation, will give the engineer at least a basis from which to make a fair estimate of what his lock will do. In case any of the observations were to be repeated or a closer study of the form of the curve near the origin was to be made, the following method of observation is suggested: In the place of a gauge use the rise or fall of a barge, as in the case of the Soo Lock. This could probably be most conveniently done by reading the changes with a level from a tape suspended at the center and plumbed to a vertical. It would be best in this case to call even intervals of time-say every ten secondsand at each call of time have the tape read and recorded. This would practically eliminate all error in the time observation and give a simultaneous observation of the stage in the lock, so far as the average of the area covered by the barge would represent it. The calling of time might begin approximately at the beginning of opening the valves (exact coincidence in the beginning is of no importance here), while at the end, as soon as motion had stopped, the man at the level should call this to the timekeeper, and the fraction of an interval there be recorded. In case there was a restricted waterway, a gauge above or below the lock should be read at intervals to give the coincident variation of head, as in the data of the Soo Lock. With data so taken, the intervals of time reduced to the standard, and in case of any variation further corrected to a constant head of pool, as in the Soo data, when summed for total time and platted to the corresponding observed elevations, would give, in comparison with the group of curves on Pl. I, the value and the character of the actual coefficient of efflux in the lock with great accuracy, and could hardly fail to develop, in its comparison with other data, a fairly definite series of values for the coefficients corresponding to different types of design. Since the plates were made up, several sets of observations have been received that are not included in this study, and in the process a number of locks where there was but a small lift were not considered, since between the opening of the valves and the final level there was but little data from which to determine a regular coefficient. Very respectfully, your obedient servant, Capt. HIRAM M. CHITTENDEN, Corps of Engineers, U. S. A., JAMES A. SEDDON, Assistant Engineer. Secretary Missouri River Commission. APPENDIX M. CEMENT TESTS BY MR. F. B. MALTBY, ASSISTANT ENGINEER. ST. LOUIS, May 30, 1897. CAPTAIN: I have the honor to submit the following report of the results of experiments made with cement to determine the adhesion of Portland and natural to each other when mixed at the same time; also the results of some experiments made with concrete bars. Neat cement of the two different kinds was mixed separately and placed in the opposite ends of the same briquet mold. The two cements were kept apart by a knife blade placed as near the center of the mold as possible, until the mold was filled. The knife was then withdrawn and the cement firmly pressed and rammed into the mold. Thirty-six briquets of various combinations of cement were made. They were allowed to stand in air twenty-four hours and in water six days, and then broken. Not a single specimen broke through the joint, but in every instance the break was in the natural cement, sometimes as much as one-fourth inch from the joint, showing that the adhesion of the two cements was greater than the strength of the weaker cement. By the kind permission of Mr. M. L. Holman, water commissioner of St. Louis, the experiments were made at the city testing laboratory, at 2322 Clark avenue, by Mr. A. S. Ferguson, who is in direct charge. The appliances and methods used are those of the best modern practice, and as all the cements used by the city in the water, sewer, and street departments are tested here, the assistants are thoroughly experienced in the necessary manipulations for making accurate tests. For these reasons I have great confidence in the reliability of the results attained. The following table shows the breaking strain per square inch of the various specimens: All the Louisville was from the same mill (J. Hulme). A number of concrete bars were made in molds by 6 by 27 inches long, and kept for various lengths of time. The concrete was made of cement (weighed), Osage River sand, and Osage River gravel. The sand is a very good one, being perfectly clean and sharp, but contains possibly a little more than the ordinary proportion of fine particles; it contains 37 per cent of voids. The gravel is a very clean, hard, water-worn flint, containing 37 per cent of voids. An inspection showed the concrete made of natural cement to be very unsatisfactory for use in constructing lock walls. To determine the adhesion of the two kinds of concrete, several bars were made with one-half made of Portland and one-half of natural cement. The joint was made as near the center of the mold as possible, but no smooth joint was made. On the other hand, care was taken that the two kinds of concrete should interlock, and were thoroughly rammed together. All concrete was mixed with as much water as it would hold without quaking, and was thoroughly rammed with an iron rammer weighing about 10 pounds. The molds were thoroughly soaked in water before being used. They were put together with screws so that they could be taken away from the bars without disturbing them. The bars were kept moderately moist for about a week after making them, and were kept under cover from the sun for the entire time. The attached table gives the results of 15 bars which were broken. Nos. 5, 6, 10, and 13 were combination bars; none of them broke through the joint, showing that the joint was stronger than the weaker concrete. Nos. 4, 7, 11, and 12 were Louisville bars, made respectively at the same time as above combination bars, and, with the exception of Nos. 4 and 5, the combination bars were the strongest. Nos. 1, 2, and 3 are bars of Portland concrete made in theoretical proportions necessary to just fill the voids in the sand and gravel. Nos. 1 to 8, inclusive, were made of unscreened Osage sand; Nos. 9, 12, 13, and 15 of unscreened Meramec River sand, which is considerably finer than Osage sand. Some question having been raised as to the effect of fine sand, Nos. 10, 11, and 14 were made of sand screened to pass a No. 20 and be retained on a No. 30 screen. No. 15 is a bar made of Portland cement in proportion of 1-4-9.5. The proportions given are for parts of packed cement weighing, for natural, 75 pounds, and for Portland, 104 pounds per cubic foot, and for parts of loose sand and gravel. It is realized that a much larger number of tests should be made in order to draw any definite conclusions as to the relative strength of various cement concretes, but it is hoped that the list attached may be of some value. Very respectfully, your obedient servant, Capt. HIRAM M. CHITTENDEN, F. B. MALTBY, Assistant Engineer. Corps of Engineers, U. S. A., Upper half of briquets imported Portland; lower half of briquets native natural. Nos. 1 to 10, inclusive, Alsen imported Portland] and Utica, Ill. [natural]. Nos. 11 to 18, inclusive, Alsen [imported Portland] and Louisville, Ky. [natural]. Tabular statement of strength of various concrete bars. [All bars were made 27 inches long, supported 24 inches apart, load applied at center.] ANNUAL REPORT OF MR. L. P. BUTLER, ASSISTANT ENGINEER. ST. LOUIS, MO., December 5, 1896. CAPTAIN: I have the honor to report on the work of improving the Gasconade River during the fall of 1896. In the office there were platted thirteen sheets and an index sheet from the notes of the survey of the Gasconade River in 1895. These sheets represent 29.5 miles of river between Indian Head and Arlington, Mo. They are platted with soundings and profiles, and are all inked with the exception of hachures and cultivated land, which are indicated in pencil. The accumulation of materials at the mouth of the river was begun October 31. The construction of a barge was begun September 1 and completed September 19. The barge built is 50 feet long, 15 feet 10 inches beam, and 19 inches deep. The deck, bottom planking, and gunwales are of yellow pine; the frames, bracing, and all inside work of white pine; and the end blocks and nosing of oak. It was designed for carrying rock over shoal water, and for that reason was built shallow, which necessitated a longitudinal bulkhead. It was only required in loading that the greatest weight be put at the ends. It was fitted with one Providence hand capstan. While the barge was being built a force was put to work quarrying rock and getting out logs at Bocks Bar. This work was completed when the barge was ready for use, and the quarry force was sent to Woodpecker Island while a separate force was engaged in the construction work at Bocks Bar. The season's field work consisted in the construction of dikes to direct the water at shoals and in the removal of snags. The dikes are built of cribs filled with rock and backed with rock on either side. The backing on the pocket side of dike is laid on willows. The cribs are built of 20-foot logs with cross pieces 3 feet from each end, notched in. The width of cribs |