The supply of water will in this case, also, be obtained from a reservoir, to be constructed on Anthony's Creek, a tributary of the Greepbrier, whence it will pass through a tunnel two and one-half miles long, and a feeder-canal of six and one-half miles to the summit-level. The distinguishing features of the low level is the long tunnel, longer even than that of Mount Cenis, just now reaching completion; differing from that work, however, in one important particular, that while the Mount Cenis Tunnel was excavated exclusively from the two ends, the one now in consideration can be worked from six shafts as well as from the ends, forming fourteen faces upon which simultaneous progress can be made. The section recommended and adopted for the estimate is 52 feet wide and 34 feet high, the water-way being 7 by 46 feet, with a tow-path of· 6 feet and semicircular roof. I have no doubt that steam in some form will be used as the motive power in this tunnel, but have thought it necessary to provide a narrow tow-path, rather as an assistance in case of accident, than as an auxiliary to navigation. This narrow tow-path is extended through the rock-cuttings of the approaches to the tunnel, in which also the width at water-surface is somewhat reduced, while retaining an equal section. The extreme length of tunnel is 40,380 feet, and, for the purpose of diminishing the depth of shafts, has been located upon a curve of nearly thirty miles radius, although in construction the tunnel would be made straight from shaft to shaft. The shafts vary in depth from 333 to 693 feet, and the greatest distance between any two of them is 7,500 feet. The cost of the tunnel varies with its width. Being of great length, it must afford room for the passage of loaded boats moving in opposite directions, and, for the same reason, the resistances to traction, which are directly dependent on the width of water-way, must not be too largely increased. The dimensions. given allow 6 feet for guard-timbers and for space between passing boats, and the resistances will be about 25 per cent. greater than on the 70-foot canal. The rock through which the excavation will be made is slate and sandstone, of variable quality, from a sandstone shale to the most solid character of rock. Lying below the summit crossed at a depth of 1,000 to 1,300 feet, it is reasonable to suppose that a large portion of the rock will be sufficiently firm and solid to stand without a lining arch. I have, however, included in the estimate the cost of arching one-half of the whole length of the tunnel. The cost, as estimated, of this line from the mouth of Fork Run to the Greenbrier is .... And by the high-level route... Difference against the low level... $15, 636, 757 7,959, 564 7,677, 193 Before comparing these two routes as to the relative cost of transportation over them, we must determine as the elements of computation the probable tonnage and the cost of transportation, per ton, per mile. On the Erie Canal 198 boats have actually been passed through a single lock in one day; we may then safely assume a capacity for 180 boats. The tonnage of the boats which will be used will be about 280 tons, but as the freight going west will not be more than one-fourth of that from the west, we will average them at 180 tons, which will show a trade of 9,720,000 tons per annum or for a season of three hundred days. The actual excess in length of the high-level route is about three and one-half miles; the whole amount of lockage is 432 feet. This being equated by the rule deduced from observations on the Erie, is equal to thirty-seven miles of level canal, making the equivalent difference in length equal to forty and one-half miles of level canal. The cost of transportation on canals of these dimensions is stated by McAlpine, in his report of 1854, to be four mills per ton per mile. The officers of the Erie have found it to vary from 2.16 to 2.25 mills per ton per mile up to 1866, and in 1868 to have reached 4.6 mills. I make the cost on present work, reduced to a level, 2.3 mills. Applying then this price we have 9,720,000 tons by 403 mills by 2,3 mills $905,418. Which, at 7 per cent., is the interest on. We have seen the excess of cost of the low level over the higher route to be........... But this result shows that the actual saving in cost of transportation by the lower line represents a capital of.. $12,934, 542 7, 677, 193 5, 257, 349 On the flat ground adjacent to the river it is proposed to construct a basin, in which cargoes can be transferred from the large barges navigating the rivers to those proper for use in the canal. WATER-SUPPLY. We have assumed a trade of 180 boats per day, but it will be prudent to provide a supply of water for 200. Allowing them one and one-half locks full of water to each boat passing the summit level, we will require three hundred locks full of water per day for a maximum trade. The greatest lift between Greenbrier and Covington, the portion of the line to be supplied from the summit level, is 14 feet, and the locks being 120 feet by 20, we have 300 locks by 120 by 20 by 14, equal to cubic feet, per day, 10,080,000. Evaporation on 21.9 miles, (the tunnel being excluded,) inch per mile per day, cubic feet. Filtration, cubic feet... Waste at structures, cubic feet. Leakage at lock gates, cubic feet Total. The minimum flow of the Greenbrier, as gauged by Cap- And we have available for the canal.. 225, 264 5, 240, 400 43, 200 1, 728, 000 17, 316, 864 8, 380, 800 8,936, 064 1,072, 327, 680 5, 484, 229, 000 899, 405, 100 4, 584, 823, 900 3, 512, 496, 220 As fears have been expressed by some persons not familiar with the subject, that a reservoir supplied chiefly from rain-fall might fail to furnish the anticipated supply, it is well to observe that the valley of the Greenbrier River is extremely favorable for the construction of reservoirs, with which it might be filled throughout its length of sixty miles; in which any desired amount of water from the spring and winter floods might be stored up for use in time of drought. At the mouth of Howard's Creek the canal, having passed the Alleghany summit, is terminated. The means of its ultimate connection with the Ohio is next to be considered. The valley of the Greenbrier River is narrow, limited on one or both sides by steep bluffs or cliffs. The flat land is small in quantity, and in no place continues for any considerable distance. The improvement recommended by Mr. Gill, partly canal and partly slackwater, would be the more economical for a work of the dimensions proposed by him, but the larger canal now under consideration would not find room in many places along the river bluffs without too serious a reduction of the water-way of the river itself. I therefore recommend a continuous slackwater, (broken at two points only by short sections of canal,) which would be extended to the mouth of the river by nineteen dams of heights varying from 10 to 35 feet. At Alderson's, and again a short distance below the falls of Greenbrier, short canals of large dimensions are introduced to avoid very expensive locations for dams, which would otherwise be required. The length of the river is 49.086 miles, and the total fall 316 feet. New River is, particularly in its lower portions, of a different character, the banks being composed almost entirely of boulders, among or over which the construction of a canal presents formidable difficulties. These, however, are not in the way of a slackwater improvement, as is now recommended. The river and its valley are remarkably favorable for a work of this character, except in one single particular, and that is the difficulty (on a hurried reconnaissance) of determining rock sites for dams. The river is in many places filled with boulders of every size, sometimes immensely large, and it is not possible, generally, to estimate their depths. At such points the · cost of foundations cannot be determined in advance. I have therefore deemed it necessary to locate dams at those places only where the ledgerock can be discovered. In consequence, some of them are higher than I could have wished, and the estimate proportionately greater. It is probable that better sites will be found by a more detailed survey, and that the cost will thereby be reduced. Indeed, I expect a thorough survey greatly to diminish the estimate. It was not possible, in the time and with the force at my disposal, to undertake an examination in detail of the pools and shoals, with a view to make a final location. A height was therefore taken for each dam sufficient to raise the water 7 feet at the foot of the one next above, without regard to its present depth. The length of New River from the mouth of Greenbrier is 67.433 miles; the fall in this distance, 756 feet. The upper portion of the Kanawha from the mouth of Gauley River to the foot of Lyken's Shoals requires the same kind of improvement as the Greenbrier and New Rivers; the fall being too great for any open navigation, its cost is included with those rivers. The whole number of dams required is 55, varying from 12 to 41 feet in height, and in length from 200 to 600 feet. They are to be constructed of heavy rubble masonry, laid in bydraulie cement, and covered on top with timber and plank. DIMENSIONS AND PLAN OF SLACK-WATER. The locks are designed to be 200 feet in length between the gates, and 40 feet in width at the lower water-line, with 7 feet depth of water. These dimensions will admit a barge of 700 tons, or two canal boats for the enlarged canal. The locks as well as the dams are to be constructed of heavy masonry, with guard walls from 10 to 20 feet above the coping of the dams, the head walls and upper gates of the locks being carried up to the same height as a protection during floods. On the Greenbrier the maximum freshet-rise is about 20 feet. It varies on different portions of New River, rarely exceeding 8 feet at Richman's Falls; 30 to 35 feet from Stretcher's Neck to Bowyer's, or, perhaps, to Miller's Ferry, and for a few miles below the latter point from 40 to 50 feet. At the Blue Hole, where the river, having fallen 62 feet among precipitous cliffs in the preceding two miles, turns at a right angle and meets a lighter grade, the engineers of the Chesapeake and Ohio Railroad have found unmistakable signs of high water, 69 feet above the ordinary surface. At these points the locks will be, of course, submerged, but their construction will be such as to preserve them from injury. The lock gates will be made of iron frame, and covered with plank, and furnished with suitable gearing for maneuvering them. By reason of the necessary height of the upper gates, they will rest on breast walls, and the influx-valves will be placed in culverts communicating directly with the pool. The efflux-valves will be placed in the lower gates. The large locks on the slack-water will transmit the daily tonnage estimated for the canal in 120 lockages, requiring for a maximum lift of 15.5 feet, (on the Greenbrier,) with 25 per cent. added for waste, 120 by 200 by 40 by 15.5 by 1.25, cubic feet. Which being supposed necessary for 120 days, the re- But Anthony's Creek reservoir will furnish, beyond the 18, 600,000 2, 232, 000, 000 3, 512, 496, 220 1, 280, 496, 220 During the last summer and early fall the Greenbrier was very low, said to be lower, indeed, than ever before observed by persons living at Greenbrier Bridge, but was swollen by rains before an opportunity offered to gauge it. I rely, therefore, for the low-water flow at the bridge upon Captain McNeil, who found it, as stated above, 97 feet per second, at the mouth of Howard's Creek, just below Greenbrier Bridge. A gauge made by myself, some 16 miles lower down, gave 1,000 feet per second. The river had been much higher, but had fallen to within 8 to 10 inches of its lowest period at the point where the gauge was made, and was very slowly falling. Any calculation of the relative discharge at its lowest stage, based only upon the relative section and perimeter, must, in my judgment, be speculative when applied to a river formed, like the Greenbrier, of alternate pools and rapids. The application of the formula gives as the low-water discharge at the point 603 feet per second, which must be far in excess of the truth. Not many streams empty into the river between Howard's Creek and this point, but I am of opinion that considerable quantities of water are furnished from the limestone beds which are here underlaid at a slight depth by the sandstone. The discharge of New River, when said to be at a low stage, though not its lowest, was found to be 2,000 feet per second. Besides the Gauley, several streams of considerable importance empty into the New River below the place where the gauge was made, yet the ordinary low-water of the Kanawha, which unites the discharge of New River with that of the Gauley, is but 1,300 feet per second, and has been as low as 1,100 feet at Buffalo Shoals, thirty-five miles below Charleston. If, therefore, the water of New River sinks, as has been supposed, it does not come out at the Salines or any other point of the upper Kanawha, but the fact is, as before stated, that the minimum flow of a stream of these varying characteristics cannot be directly deduced from the observation made at any other stage. From Lyken's Shoals to the Ohio, at Point Pleasant, the distance is 85.1 miles, and the average fall about .873 foot per mile, and as with this fall an open navigation is practicable it is also highly desirable. Among the plans proposed, that of sluice dams, by Mr. Fisk, is the most simple of application and certain in its results. His theory is to grade the river by means of dams at the shoals, to be spaced about onequarter of a mile, containing sluices of uniform dimensions. (I would fix them at 100 by 7 feet,) and with but 6 inches fall at each dam, thus lengthening the steep grade of the shoal, and lightening it by extending the fall over more distance. The resistance to a tow of loaded boats passing these sluices up stream will be greater than has been supposed, (for the tow will completely fill the sluice,) and will require some modifi cations of the present method of towing. The low-water flow of the Kanawha, being but 1,100 to 1,300 feet per second, is not sufficient to fill such a sluice, but will require from 800 to 1,000 feet more. To obtain this we must have recourse to a reservoir, and I therefore include in the estimate the cost of one surveyed by Mr. Ellet for this purpose, described by him as Meadow Reservoir. His estimate, as revised, amounts to $529,080, but as one with a tenth of its capacity will be sufficient, I have placed it at $250,000. To this is added the estimate for dams, &c., by Mr. Byers, increased by 80 per cent., to allow of more permanent constructions than those proposed by him, as well as a greater depth of water, $723,900, making a total of $973,900. The mean velocity of current in the sluices will be 3 feet per second, or about two miles per hour, which will be encountered for a short dis tance only, and the wide pools between the dams will offer every facility for the passage of boats moving in opposite directions. In case the system of towing cannot be changed to occupy less width than is now usual, (I see no reason why it should not be,) then recourse must be had to locks and dams, for which the conditions are peculiarly favorable if any obstructed navigation can be tolerated. An approximate estimate shows the cost of such an improvement to be about $1,000,000. TIME OF COMPLETION. A material question is the time which will be required for the comple tion of this work. Provided funds are supplied to keep pace with their economical expenditure, the opening of the line will be governed by the time necessary to complete the long or Lorraine tunnel. If we suppose a progress of 30 feet per month to be made in each shaft, and 100 feet per month in each heading, (and double this has been made in the Mont Cenis Tunnel,) then the longest time will be consumed in the west heading of shaft No. 4, and the east heading of shaft No. 5, which will require five years and two months from the date of commencement. Ten months may be consumed in preparation and in trimming up after the opening is made through; we may therefore safely say that the work |