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20 MARINE REVIEW AND MARINE RECORD. where it connects by a Y to two pipes, also 18 in. in diameter, going to the two vacuum chambers. From each of these an 18-in. pipe leads aft to a Y, whence an 18-in. discharge pipe passes out from the stern of the boat. There are four 18-in. "valves, one in each branch of each Y. These valves are sepa- rately operated by steam pistons controlled at the pilot house. In the hopper at the entrance to the suction pipe is a cutter with four 2%%4-in. blades. This cutter is run by a separate double-cylinder engine. A high-pressure Blake pump, 1Io-in. suction and 8-in. discharge, supplies water to the hopper. A heavy A frame, 26 ft. from the bow, carries a cable passing from the engine drum to the other end of a boom 4o ft. long. This frame also carries the cables for operating the dredger bucket. This bucket is suspended from two sheaves, 30 in. in diameter, near the end of the boom. The bucket has a capac- ity of 4 cu. yds. It is of the form known as the Hayward orange-peel type, so-called from its resemblance to the peel of an orange. when cut into quarter pieces. It has four triangular curved blades, which, when closed, form a tight semi-spherical bowl. When open the blades resemble sharp spades, and are so: adjusted to steel arms, connecting rods and cables, that the maximum downward digging effect is produced with but slight tendency to lift the bucket until closed. The dredging is done by the main engine placed at the back of the pilot house. This has cylinders 14x18 in. and two drums 30 in. in diameter car- rying the hoisting cables. A 4-in. high-pressure Blake pump supplies water to the vacuum chambers and is regulated by pres- sure valves, so that it will stop acting when the chambers have the requisite pressure. A direct current generator supplies electric light. All machinery is controlled by levers placed in the pilot house at the bow of the boat. The dredging is done by the orange-peel bucket in the ordi- nary manner. This lifts the material from the bottom or sides of the excavation and drops it into the hopper, which is sup- plied with water by the large pump. The cutter is revolving in order to disintegrate the mass of excavated material. Steam is turned into one of the vacuum chambers, and then cold water is pumped in through a spray, condensing the steam and forming a vacuum. The forward valve is then opened and the water and excavated material drawn from the hopper into the chamber. The valve is then closed, the rear valve opened, steam turned into the chamber, forcing the water and excavated material into and through the discharge pipe; Whijle one vacuum chamber is dischareing the other should be filling, their work alternating and the discharge made practically continuous. An orange-peel bucket with a capacity of 1 cu. yd. had been suc- cessfully operated in excavating the soft clay from the canal near the Grasse river. 'This was supported on a moveable plat- form on land. The clay was wet but not under water. It was expected that this large floating dredger would be more advan- tageous. It was found, however, that this large bucket was quite incapable of excavating the indurated material. It could not move sufficient to pay for its maintenance. It could exca- vate the soft material, but the hopper, the cutter and the vacuum method of transmission failed to transport the material with economy. It formed into balls and lumps in the hopper and did not: flow with the water as suspended material. but rather as small separate masses carried through the pipes. The steam capacity, though large was not sufficient to operate the vacuums alternately with continuity, and thus, instead of a steady flow through the discharge pipe, there was an intermittent series of impulses. The attempt to use these vacuum orange-peel dredg- ers for this excavation was abandoned, and one of them was rebuilt as the centrifugal pump dredger with 18-in. discharge pipe, described above. The other vacuum dredger was sent to the vicinity of New York, and is working on material quite dif- ferent from any encountered in the canal. No ladder of continuous scoop dredgers were used on this - work. Experience on the St. Lawrence river not very far from. this locality had shown good results from such dredgers, and it is regretted by the writer that the contractors did not place at least one such in operation. _ SUMMARY OF RESULTS WITH DIFFERENT MACHINES. Now let us summarize the statements above made: The total amount excavated by dredgers in this canal was. 1,436,000 cu. yds. There were in addition excavated by other means 4,433,000 cu. yds. : The vacuum pump dredgers with orange-peel buckets and pipe transmission lines were not serviceable in excavating and transmitting either the indurated or the softer material. The centrifugal pump dredger. excavating by revolving cut- ter to depths under water not exceeding 22 ft., lifting the mate. rial to a height of 30 ft. above water and depositing it through a pipe of 12 in. diameter, 1,200 ft. distant from the canal, could.. not excavate the indurated material but worked with success in the softer material. It excavated and deposited in three sea- sons 459,800 cu. yds. of this material at an average cost of 8,507 cents per cubic yard, this cost including labor, supplies, coal, repairs, renewals and. care during the winter seasons. The centrifugal pump dredger, generally similar to the one last mentioned but with a discharge pipe 18 in. in diameter, working in the softer material, excavated and deposited in two seasons 290,780 cu.; yds. at an average cost of 9.399 cents per : WEEE Sen 4 [Oct. 2, cubic yard. The centrifugal pump dredgers worked twenty- two hours of each twenty-four hours. _ The dipper dredgers excavated during three seasons 525,306 cu. yds, This was indurated material. It was deposited in scows and towed by tugs and deposited in water about 5,500 ft. from the dredgers. One of these dredgers with a dipper of 2% cu. yds. capacity, working ten hours each day and excavating to a depth of 20 ft. below the water surface, lifted and delivered 138,001 cu. yds. in 183 working days of ten hours, at an average cost of 8.004 cents per cubic yard, this cost including labor, sup- plies, coal, repairs, renewals and care in winter, for the dredger, scows and tug for towing. Coal is included in these statements at a cost of $3 per ton; the modification for a different price of coal can be readily found. In latitudes where dredging can be done during all seasons of the year the modification required can be easily made from the data above given; the cost per unit will be reduced provided also there is continuous work for the dredger throughout the year. MANCHESTER OIL INDUSTRY. London, Sept. 20--American ship builders are naturally in- terested in the building of ships specially put together for the transport of petroleum. The latest of its kind is the steamship Pectan, built by William Gray & Co. of West Hartlepool, to the order of M. Samuel & Co.,-for the Shell Transportation & Trad- ing Co. 'The vessel is the largest bulk oil steamer afloat, and is the ninth built by Gray & Co. for the Shell company. Her dimen- sions are 483 ft. over all, extreme breadth 55 ft. and depth 34 ft.; the registered tonnage is 7,300 tons, deadweight capacity 10,100 tons, and capacity for measurement of goods 14,000 tons. The bunker spaces are constructed to carry either coal or oil for fuel, and there are eighteen separate cargo compartments in addition to cofferdams and other spaces. Oil pipes, fitted with controlling valves, are carried throughout the oil compartments, and shore connections fitted to each side amidships and over the stern. Two pumps are placed in the pump room capable of discharging 300 tons of oil per hour. The Shell company is certainly a won- derfully go-ahead concern. In ten years it has brought together thirty-eight vessels with a deadweight capacity of 152,000 tons, and they are now the fourth largest company sending ships through the Suez canal. The enterprise has been built up without a shilling subsidy from any government. The board of trade has now passed a vessel using liquid fuel for passenger traffic, and this is a most important step in advance; it is indeed a landmark in the progress of this special kind of enterprise. At the dinner cele- brating the launch of this vessel Mr. Melrose of the admiralty said they had not adopted liquid fuel for consumption in the British fleet at present, but he was free to confess that the time was not far distant when the strategical value of it alone would make it the fuel for war service. The present difficulty was the price. This gentleman is by way of being a prophet, for he told the company that the time would come when the British people would recognize that there would be a clear and tangible return for any money outlay upon liquid fuel. MANCHESTER AND OIL IMPORTS. Mention of the transit of petroleum reminds me of a point I did not sufficiently develop last week in my comments upon the port of Manchester. With the single exception of London, which remains without a British rival in the magnitude of its petroleum imports, Manchester has now a larger share of the oil trade than any other port in the United Kingdom. Liverpool, which follows it closely, is falling behind on account of its greater dis- tance from the most important centers of consumption, and be- cause the Mersey docks and harbor board does not permit the election of oil storage tanks on the Liverpool side of the river. For these reasons petroleum companies seeking sites for storage and distributing plants in Lancashire have recognized that on the banks of the Manchester ship-canal, where there is plenty of cheap land and direct communication with the railway and inland canal systems of the north and midlands, the trade can be conducted with the greatest economy and advantage. Since 1897, when the first petroleum tanks were erected by a Russian company, there has been a rapid and almost uninterrupted increase in the annual imports of oil to Manchester. Before that date all the oil im- ported was in barrels, but although the barrel trade has been maintained and even increased, it is in the imports by tank steam- ers that the most remarkable development has-taken place. Im- ports in barrels have averaged about 25,000 tons annually for five years past. 'The bulk imports in round numbers aggregated 21,000 "tons in 1897; 57,000 tons in 1898; 90,000 tons in 1899; IOI,000 tons in 1900, and 81,000 tons in 1901. The imports during the first eight months of the current year were at the rate of nearly 9,400 tons a month, or 112,400 tons per annum. All the oil storage tanks along the canal, with the exception of the Manchester corporation gas committee's depot near Mode Wheel locks, have been erected by private enterprise, and are privately owned. At Eccles the Consolidated Petroleum Co., (which represents the Rothschild Russian interests) has five tanks, with a capacity of 22,000 tons, or about 5,750,000 gallons: The twelve tanks at Mode Wheel, owned by the Anglo-American Oij