SI'IIMAIMM-: TTXXEL1XG 235 



It was finally decided that the old plan of deflecting the 

 line toward the north and upward so as to pass over the under- 

 ground stream should be tried. A hole was therefore cut 

 through the tunnel lining 1,433 ft. from the shore, and work 

 was begun on a detour of 20 toward the north and an upward 

 grade of 10 %. Fair progress was made on this new line, 

 gradually ascending into solid rock, until May 10, when the 

 test borings, which were constantly made in every direction 

 from the face, showed that sand was being approached. A 

 brick bulkhead was therefore built into the masonry as a safe- 

 guard, should it happen that water was encountered in large 

 quantities. As the borings seemed to indicate that the top 

 surface of the rock underlying the sand was nearly level, the 

 lower half of the tunnel was first excavated, leaving about 18 

 ins. of the rock to serve as a roof (Sketch a, Fig. 121), and the 

 brick invert was built for a distance of 52 ft. The rock roof 

 was then carefully broken through for short distances at a time, 

 and short sheeting driven ahead into the sand, which proved to 

 be a very fine quicksand flowing through the smallest openings. 

 Extreme care had to be taken in this work, but little by little 

 the brickwork was pushed ahead until at a distance of 90 ft 

 from the point where the sand was first met, and 208 ft. from 

 the old tunnel, the sand stopped and the heading entered a 

 hard clay. 



All this work had been done on an ascending grade, and the 

 ascent was continued about 40 ft. farther in tin- clay. My this 

 time a sufficient elevation was gained to pass over the under- 

 ground stream, and the tunnel line was changed to head toward 

 tin- bike shaft, and the grade reduced to a level. The under- 

 ground stream was passed without trouble and the tunnel 

 continued for a distance of 54 ft. without difficulty. On July 

 10 the clay in the heading suddenly softened, and before the 

 miners could secure it by bra'-iui,'. the water rushed in, followed 

 by gravel, filling up solidly some 34 ft. of the tunnel before it 

 was stopjK'd by a ti:uln.T bulkhead hastily built 



