This disaster delayed the work for some time, but in June the contractors erected a new building and new machinery, and resumed work. Very little progress was made; and the air escaped so rapidly that it loosened the sand surrounding the shaft and reduced the friction to such an extent that on July 28 the entire cylinder lifted bodily about 6 ft., and sand rushed in, filling the lower part of the cylinder to within 45 ft. of the lake surface. No further work was done by the contractors although they submitted a proposition to sink a steel cylinder inside the cast-iron cylinder and extending from 5 ft. above datum to 100 ft. below datum for $300 per ft. This proposition was refused by the city; and since work on the tunnel proper had been abandoned by the contractors some time before, as had already been described, the city suspended their contract on Oct. 19. On Oct. 30 a contract was made with Mr. Thos. Murphy of Milwaukee, Wis., to sink a steel cylinder inside the old iron cylinder. The water was first pumped out of the old cylinder, and a timber bulkhead built at the bottom. On this the steel cylinder was built, and then the bulkhead was removed. Air pressure was put on, and the excavation proceeded successfully until the bottom layer of clay was met with, when all chances for trouble ceased. The cylinder, as it was completed, penetrated 9 ft. into the hard clay, and was underpinned with brickwork for a depth of 29 ft. or more, to a point 4 ft. below the grade line of the tunnel. At the lower end, the section of the shaft was changed from a circle to a square. Later the steel cylinder was lined with brick. On March 28, 1894, an agreement was made with Mr. Thos. Murphy to construct the tunnel from the lake shaft toward the shore. Except that considerable water was encountered, which, owing to inadequate pumping machinery, filled the tunnel and shaft at two different times, and had to be removed, no very great difficulty was had with this part of the work. On July 28, 1895, the headings from the lake and shore shafts met. Meanwhile the cast-iron pipe intake, the intake crib, etc., had been completed, and practically all that remained to be done was to clean the tunnel and lift the pumping machinery at the shore shaft. During the cleaning, the air pressure had been kept up on account of the leakage through the brick lining, and, indeed, the pressure was kept up until the last possible moment, and everything made ready for removing the air-locks, bulkheads, pumps, etc., in the least possible time. The pumps were the last to come out. CHAPTER XIX. SUBMARINE TUNNELING (Continued). THE SHIELD SYSTEM.