́ations for the completion of the work were based upon the deductions derived from the sources reported by Mr. Townsend, and are, therefore, unreliable, and others must be made. Colonel Houston designed to remove the southwest ledge itself, and for all these works he thought $65,000 would be sufficient. (See Ann. Doc. for 1868.) Captain Dutton's estimate for the removing of Middle Rock, and the two adjacent to it, to a depth of 17 feet below mean low water, was as follows: (See Annual Report of November 8, 1853; President's Annual Message for 1853, pp. 291-295.) Middle Rock, 1,330 cubic yards, (at about $18). $36,000 12,000 30,000 78,000 Captain Dutton gives no reasons for such different rates per cubic yard for Middle Rock and the others. According to our measurements in 1870, after stopping work, there were 728 cubic yards yet to be removed to get a depth of 17 feet on it at mean low water. As we know that a quantity so great as the difference between our measurement and Captain Dutton's had never been removed, we made calculations of the amount from his survey of 1853, and cannot make the amount to be removed at that time greater than 768 cubic yards. There has evidently been a mistake made somehow. Captain Dutton, it seems to me, reported the amount much too large; but there is a compensation in the cost of removing by his taking it at so much less than the others. I see no reason why there should not have been the same cost per yard estimated for Middle Rock as for the others. The amount of rock removed from Middle Rock, under my direction the past season, was 23 cubie yards. For this I paid Mr. Townsend $2,210; besides this, I paid $250 for powder-fuses, exploders, cartridge-cans, &c., not counting superintendence. This is an expenditure of $2,460, or at about the rate of $107 per cubic yard. The season was unusually favorable, and I do not think that, with the preparation which the little appropriation afforded, we could do better hereafter. Applying this to the quantity of rock yet to be removed, we have the following: For Middle Rock, 728 cubic yards, at $107. $77,896 25, 573 64, 200 167,669 I have no measurement of Luddington's Rock. With ample prepararation, we might be able to remove these rocks at a rate of $50 per cubic yard, which would make the above estimate become $78,350. I would therefore recommend that an appropriation be made of that amount, and if this cannot be afforded, that the work be for the present abandoned. The history of the removal of the Middle Rock, which I have given in the preceding parts of this report, shows that Mr. Maillefert expended upon it.. $1,975 Captain Dutton and Colonel Houston, (for the United States)... 6,000 Myself, (for the United States)...... 6,000 Total... 13,975 Comparing our survey with Captain Dutton's, we have all together removed 40 cubic yards of the rock, costing on the average $349 371 per cubic yard. If we go on in this way, there is no way of judging what amount of money might be expended in a long time before the work would be accomplished. I do not care to estimate on such a basis. The only way to do the work of improving the entrance to New Haven Harbor is to take the full measurement of what is to be accomplished, suppose that sufficient means will be granted, and make such estimates as the magnitude of the work to be done requires, and the preparation for the work made proportionately. The business of New Haven requires that there should be a channel dredged 200 feet wide and to a depth of 14 feet at mean low water, up to the wharves. At present there is not more than 7 feet at mean low water. The mean rise of tides is 5.8 feet. To make the required channel would require the removal of 259,260 cubic yards of ordinary dredging material, at a cost of 25 cents per cubic yard, requiring $64,815. This dredging is in many respects more important to New Haven than the removal of the rocks at the entrance to the harbor. New Haven harbor is a fine harbor of refuge for coasters. Immense fleets anchor here in unfavorable winds. It deserves all the consideration due to an important harbor of refuge against disasters and loss of life that attaches to such places. . New Haven is in the collection district of New Haven; it is its own port of entry. The amount of revenue collected during the last fiscal year was $234,773 38. The harbor is in the third light-house district, and there is a lighthouse on the east side of the entrance. There is a fort constructed for its defense. In view of the importance of the harbor, I would recommend that Congress regard the complete improvement as an object worthy of the consideration of the Government, and that a liberal appropriation toward the end be made, so that preparation can be made adequate to its full attainment. With this view, it is therefore recommended that an appropriation be made for improving New Haven Harbor of $75,000. Accompanying this report is a sketch showing the general position of the rock at the entrance to New Haven Harbor. A tracing of the survey of Middle Rock, made by Captain Dutton in 1853, in black. A tracing of the survey made by Benjamin Maillefert in 1853, in blue. A tracing of the survey made by ourselves in 1870, in red. The tracings of Middle Rock are so arranged that they can be readily compared by superposition. I send also the report of Mr. George H. Mann, civil engineer, who superintended the operations at Middle Rock the past season. Yours, respectfully, G. K. WARREN, Major of Engineers, Brt. Maj. Gen., U. S. A. Brigadier General A. A. HUMPHREYS, Chief of Engineers, U. S. A. ENGINEER OFFICE UNITED STATES ARMY, Newport, Rhode Island, January 20, 1871. GENERAL: I have the honor to submit the report of operations at Middle Rock, New Haven Harbor, Connecticut, together with the information in regard to other obstructions in the harbor, and the deductions drawn from a careful survey of the rock. Operations were commenced at the rock on the 6th of September, and were continued until the 13th of October, when, in accordance with your orders, the work was stopped. During the time the weather was unusually favorable, but nine days being lost on account of bad weather, out of a total of thirty-two and a half, and most of this was owing to comparatively light winds, which, on account of the exposed position of the rock, prevented operations, the progress of the work was not at all satisfactory, but 50 tons being removed in twenty-three and a half working days, or less than two tons a day. I consider the failure of the operation due to the following causes, which could in future attempts be obviated: 1st. Insufficient numbers and bad form of drills. 2d. Improper placing of the drill-holes, causing them, when blasted out, to form simply a crater, owing to the line of least resistance being too great for the explosive energy of the powder. 3d. Defective hoisting-apparatus, much time being lost in chaining rock, which would have been saved by improved apparatus. 4th. No means of sharpening drills, which, owing to the exceeding hard character of the rock, became very rapidly dull, especially when the drilling-machine is run at a velocity sufficient to secure rapid progress. 5th. Too much reliance on face and surface blasts. Experience here and elsewhere has demonstrated the waste of time and powder in attempting to blast granitic rock by this method; the resistance of the water is inadequate to cause anything like enough concussion to shatter the rock; and in order to remove rocks of this character, drilling must be resorted to. 6th. Non-adaptability of the drilling-machine to the character of the rock. This will be evident when the record of the progress is stated. The best duty done was at the rate of 5 inches an hour, the hole being 4 inches in diameter. The average duty is not over 4 inches per hour. The average number of strokes per minute was about fifty, when at least one hundred is necessary for rapid drilling. The machine is liable to derangement, and though well enough adapted for soft rock, does not strike a heavy enough blow to produce much effect on a rock as hard as Middle Rock, the stroke being but 8 inches, and the weight striking only 125 pounds. Middle Rock is marked by a red spar-buoy placed by the Light-House Board, and is about one and one-fourth miles from the New Haven light, in a south-by-southwest direction. It is about 75 feet by 90 feet, running in a northeast and southwest direction. The composition is that of a coarse-grained, yellow, granitic rock, the quartz being largely in excess, thus rendering it very difficult to drill. After the conclusion of the blasting operation, a survey was made by anchoring two vessels in parallel lines 60 feet apart. The sides of the vessels were marked off in distances of five feet. A nine-thread line, with strips of red bunting inserted into a distance of 10 feet, was employed to sound along, the soundings being therefore taken at the corners of rectangles 5 feet by 10 feet. The soundings were reduced to mean low water, and give, as the least depth on the rock, 10 feet. The rock is abrupt on the northwest side, running up to a peak, and sloping quite gradually on the southeast side. The water about the rock has a depth of 22 feet at mean low water. I am unable to see that Mr. Townsend accomplished anything of importance in 1867, the survey failing to show not only that the depth of water over the rock had been increased, but also soundings taken about the edges of the rock give no evidence of the large quantities of rock asserted to have been tumbled into deep water by Mr. Townsend. In case it should hereafter be determined to remove the rock, I would recommend that a vessel and working-party be hired directly by the Engineer Department, and that either nitro-glycerine or gun-cotton be used in connection with powder. Nitroglycerine could be readily made on shore and taken out when required. Also, that some investigations be made in regard to the working of drilling-machines, run by compressed air, for submarine working. Whatever form of drilling-machine is employed, a row of holes should be drilled along one face of the rock and exploded simultaneously. For hoisting small fragments, I would suggest a tub of boiler-iron, with a grated bottom, opening about a hinge. Middle Rock is not as formidable an obstruction to navigation as Luddington's Rock, about three-fourths of a mile to the southwest, and directly in the channel of the west entrance to the harbor. From the statements of the harbor pilots, I would conclude that the rock has over it about 104 feet of water at low water. The form is that of a frustum of a coue, about 15 feet across at the top, and running down abruptly for a short distance, and then sloping off gradually into water 25 feet deep at low water. There is, I believe, no buoy upon it at present, although one is represented on the United States Coast Survey chart. In the inner harbor Middle Bar obstructs the channel to a great extent, and should be dredged through. Until a thorough survey is made of the harbor, it is impossible to state with any degree of certainty the points at which dredging would be most advantageously done, as many changes have taken place since the last survey was made. I am, general, yours, very respectfully, General G. K. WARREN, Corps of Engineers, U. S. A. GEORGE H. MANN, Civil Engineer. T 13. SURVEY AND IMPROVEMENT OF THE HOUSATONIC RIVER, CONNECTICUT. This survey was finished and reported January 23, 1871, and printed in H. Ex. Doc. No. 95, third session Forty-first Congress. The amount estimated therein for improving the river, exclusive of the bar at the mouth, was $24,886. The amount appropriated by the act approved March 3, 1871, was $15,000. Advertisements for proposals to do the work were duly made, and the following is an abstract of those received: |