December 31, 1868, the number of arrivals and departures, and the number of vessels built." GEO. THOM, Lieut. Col. Corps of Engineers, Bvt. Brig. Gen. U. S. A. UNITED STATES ENGINEER OFFICE, Portland, Maine, July 1, 1869. Statement of exports and imports at the port of Calais during the year ending December 31, 1868, the number of arrivals and departures, and number and tonnage of vessels built. Barks. Schooners Tons... NUMBER AND TONNAGE OF VESSELS BUILT. 3 1 6 3,499 Repaired on railways and dry-docks, 107 vessels. B. M. FLINT, Deputy Collector. GENERAL: I have the honor to acknowledge the receipt of letter from headquarters, dated the 31st ultimo, asking my attention to the matter of dredging a channel through the Middle Ground of this harbor, and instructing me to communicate my views as to the expediency of building a dredging machine, and prosecuting the work by hired labor, instead of by contract, and to furnish estimates for the same. I have deferred making this report, in compliance with former instructions, as I have not been able to fully make up my mind as to the kind of machine which is best adapted to this work. The depth to which it is proposed to dredge the bar is twenty feet below mean low water, or twenty-nine feet below ordinary high water; and the material to be excavated appears to be generally soft mud, more or less tenacious by its admixture with clay, not, however, difficult of excavation. At times the ocean-swells upon this bar create the greatest difficulty in the prosecution of the work. It was this difficulty which the contractors (Messrs. A. B. Cooley & Co., of Philadelphia) encountered, and they were not provided with sufficient and suitable machinery for overcoming it and for completing their contract in the required time, and with satisfactory advantage to themselves; and for this last reason they doubtless abandoned the work. Of the various kinds of dredging machines now in use, the following are some to which I have directed my attention: 1. The new "plough and bucket" machine recently built at this place for Mr. Boschke, of Boston, for operations in that harbor. This machine is expensive, costing, with its requisite screws, more than twice as much as the machines and screws in ordinary use. Its capacity and advantage appear to be, and are believed to be, greatly superior to those of all other machines now in use in this country, and especially in deep water and in hard material. The capacity of this machine is claimed as six thousand cubic yards per day. The experiments thus far made with it, however, have furnished no positive information as to its great capacity and other superior advantages. I learn that in the course of the present month, it is to be fully tested in Boston Harbor. 2. The ordinary "endless chain and bucket" machine will not, in my opinion, answer the purpose in this harbor, except in very soft digging. 3. The single-dipper machine (known as Osgood's patent) is in general use, and is well adapted to digging in any material, especially in shallow water; while in deep water it loses proportionally its power and capacity for work. 4. The double-dipper machine (Morris & Cummings's patent) is much used in the harbors of New York, Buffalo, and elsewhere; and in soft material and deep water it has many advantages over most other machines in use, especially in the quantity of work it can perform, it being claimed for it that it can excavate from one thousand five hundred to two thousand cubic yards per day. I am not fully satisfied, however, as to its suitableness for the material to be dredged in this harbor. The cost of this machine and the expense of working it is about the same as that of the Osgood machine. 5. "Taggart's machine," also a double-dipper machine, is still different, though similar in its operations to Morris & Cummings's patent, and it appears to have some advantages over some others in deep water; but I know of none now in use in this section of the country, nor am I fully informed as to its merits. In my present state of uncertainty as to the advantages and merits of the Boschke machine, and the double-dipper machine, I submit the following estimates for operating with the Osgood machine, which is now in general use for work similar to that to be done in this harbor. Supposing the Osgood machine capable of excavating in this harbor two hundred cubic yards per day, and that eighty thousand cubic yards is the quantity to be excavated, four hundred actual days will be required for the work; or, adding twenty-five per cent. for Sundays, impracticable weather, and other unavoidable delays, say five hundred days, for a single machine. So that it will require more than two seasons to complete the work with but one machine, as it would generally be impracticable to work more than seven months in the year, (from the middle of May to the middle of December,) or, say, two hundred days. 1. Estimate for doing the work with one Osgood machine and hiring a steam-tug for towing off and dumping the material: Cost of one machine, (with latest improvements) Cost of four scows, at $1,250 each Repairs for two or more seasons, say.. Wages of engineer and craneman, per day. $13,500 00 5,000 00 1,500 00 20, 000 00 $7.00 10 00 8.00 Total, per day 25 00 Expense of working machine 500 days... Towing and dumping 80,000 cubic yards, at 10 cents. 12,500 00 8, 000 00 2. Estimate for two Osgood machines and hiring a tug as above: Expenses of working both machines 250 days, at $50 per day.. Towing and dumping 80,000 cubic yards, at 10 cents.. Deduct probable amount that the two machines and scows would sell for after one season's use, say... Actual cost for 80,000 cubic yards or for one cubic yard 45.62 cents. 3. Estimate for two Osgood machines and one steam-tug purchased for the work: Cost of two machines, six scows, and repairs as above.... Expense for working both machines 250 days, at $50 per day, as above... Expenses of working one tug 250 days, at $25 per day....... 8, 000 00 36,000 00 12, 500 00 6, 250 00 Deducting probable amount that the two machines, six scows, and tug would sell for after one season's use, say. 62, 750 00 26, 250 00 Nine scows, at $1,250.. Cost of excavating 80,000 cubic yards. or for one cubic yard 45.62 cents. 4. Estimate for three Osgood machines and one steam tug, purchased: Three machines.... 36, 500 00 $40, 500 00 One steam tug, say. 11, 250 00 Repairs on above, in one season 8,000 00 2,250 00 Expense of running one tug 1663 days, at $25 per day... Expense of working three machines 1663 days, at $75 per day... Deducting probable amount that the three machines, nine scows and tug would sell for after one season's use, say.. 78, 666 66 38, 666 66 Cost of excavating 80,000 cubic yards.... or of one cubic yard 50 cents. 5. Estimate for dredging middle ground bar with one Boschke machine, six scows, and one tug, purchased for the work: Expense of working machine (supposing it capable of excavating 1,000 cubic yards per day) for 100 days, at $40 per 48, 500 00 Expense of tug 100 days, at $25 per day 4,000 00 2,500 00 Total..... 55, 000 00 Deducting probable amount that the machine, scows, and tug would sell for at close of operations, say Cost of excavating 80,000 cubic yards.. Cost of excavating one cubic yard, say 30 cents. $31,000 00 24,000 00 6. Estimate for dredging middle ground bar with one single Boschke machine and eight scows, purchased for the work, and one steam-tug hired for it. Cost of machine.... Cost of eight scows, at $1,500 each. Expense for operating machine (supposing it capable of excavating 1,000 cubic yards per day) for 100 days, at $40 per day.. $27,000 00 12, 000 00 1,500 00 40, 500 00 Total... Hire of tug, running same and keeping it in repair 100 days, at $50... 4,000 00 5,000 00 49,500 00 25, 500 00 24, 000 00 Deducting probable amount that machine and scows would sell for at close of operations, say Cost of excavating 80,000 cubic yards.. or of one cubic yard 30 cents. 7. Estimate for doing the work with one Morris and Cummings machine, (double dipper,) six scows, and a steam-tug for towing and dumping the material-all purchased: Expense of working machine (supposing it to excavate 500 cubic yards per day) for 200 days, at $25 per day.. Expense of running tug for 200 days, at $25 per day Total Deduct probable amount that the machine, scows and tug would sell for, say. Cost of excavating 80,000 cubic yards.. or of one cubic yard 30 cents. From the foregoing estimates it appears: $14,000 00 7,500 00 8, 000 00 1,500 00 31, 000 00 5, 000 00 5,000 00 41, 000 00 17,000 00 24, 000 00 1. That with a single Osgood machine and four scows purchased, and with hired tug, the work can be done for thirty-seven and one-half cents per cubic yard; but that more than two seasons will be required to complete the work. 2. That with two Osgood machines and six scows purchased, and a tug hired for towage and dumping, the work can be done for forty-five and one-half cents per cubic yard, and probably in one season. 3. That with two Osgood machines, six scows and one tug purchased, |