THE MYSTIC RIVER TUNNEL.

THE MYSTIC RIVER TUNNEL.

The tunnel under the Mystic river, Mass., and the Tufts mill pond at the bridge to Everett and Malden, in the Charlestown district, one of the most difficult tasksin connection with the construction of the Boston metropolitan sewerage system, and the pumping on the opposite shore, are now completed. Owing to the nature of the river bed, a system of tunneling known as the compressed air system, introduced for the first time and operated under the personal supervision of the inventor, was employed. This system entirely did away with the necessity and consequent impediment of a temporary wooden structure and bracing to support the excavation until the masonry work was put in place. A railroad track, with cars running thereon, was constructed in the tube as the work progressed, and carried out the mud and brought the supplies of steel, brick, mortar, etc., directly to the point where the men were at work. The tunnel proper under the river bed is nearly 1,500 feet in length, 7 feet in diameter outside, and 5 feet clear on the interior, and descends by an easy grade to a point under the channel, and then ascends to the Everett shore on the side of the pumping station, adjacent to the bridge, where it connects directly with three mammoth caverns, styled pump wells, directly under the engine room. The tunnel shaft under the old mill pond was started October 2, 1888, and the works progressed without any great difficulties being encountered until its entire length of 861 feet was completed. It Is 6 feet 7 1-2 inches in inside diameter, and the tunneling was done by meanB of the ordinary timber methods, and the headings closely followed by the brickwork. It is connected with the main tunnel by a reducer 50 feet in length, the diameter of which gradually decreases from 6 feet 7 1-2 inches to the 5 feet diameter of the river tunnel at the point of connection, designed to give additional and sufficient force to the flow through the tunnel, so as to overcome any possible clogging by giving a rapid movement under the river bed. Work on the pumping plant was begun early in January, 1894, and although now practically completed, workmen, as previously stated, are still engaged in putting on the finishing touches for the trials of the pumps, the test of the tunnel and mammoth pump wells, and making all ready for occupancy. The pumping plant consists of three engines and pumps,similar in design and type to those to be used at the Deer Island station. The total cost of the work at Charlestown Neck exceeds $500,000, every detail being considered; and the wait for completion has delayed the using of the important branch in Somerville, Cambridge, and the Charlestown district.

The tunnel under the Mystic river, Mass., and the Tufts mill pond at the bridge to Everett and Malden, in the Charlestown district, one of the most difficult tasksin connection with the construction of the Boston metropolitan sewerage system, and the pumping on the opposite shore, are now completed. Owing to the nature of the river bed, a system of tunneling known as the compressed air system, introduced for the first time and operated under the personal supervision of the inventor, was employed. This system entirely did away with the necessity and consequent impediment of a temporary wooden structure and bracing to support the excavation until the masonry work was put in place. A railroad track, with cars running thereon, was constructed in the tube as the work progressed, and carried out the mud and brought the supplies of steel, brick, mortar, etc., directly to the point where the men were at work. The tunnel proper under the river bed is nearly 1,500 feet in length, 7 feet in diameter outside, and 5 feet clear on the interior, and descends by an easy grade to a point under the channel, and then ascends to the Everett shore on the side of the pumping station, adjacent to the bridge, where it connects directly with three mammoth caverns, styled pump wells, directly under the engine room. The tunnel shaft under the old mill pond was started October 2, 1888, and the works progressed without any great difficulties being encountered until its entire length of 861 feet was completed. It Is 6 feet 7 1-2 inches in inside diameter, and the tunneling was done by meanB of the ordinary timber methods, and the headings closely followed by the brickwork. It is connected with the main tunnel by a reducer 50 feet in length, the diameter of which gradually decreases from 6 feet 7 1-2 inches to the 5 feet diameter of the river tunnel at the point of connection, designed to give additional and sufficient force to the flow through the tunnel, so as to overcome any possible clogging by giving a rapid movement under the river bed. Work on the pumping plant was begun early in January, 1894, and although now practically completed, workmen, as previously stated, are still engaged in putting on the finishing touches for the trials of the pumps, the test of the tunnel and mammoth pump wells, and making all ready for occupancy. The pumping plant consists of three engines and pumps,similar in design and type to those to be used at the Deer Island station. The total cost of the work at Charlestown Neck exceeds $500,000, every detail being considered; and the wait for completion has delayed the using of the important branch in Somerville, Cambridge, and the Charlestown district.