Corner. | High. | East. | South. | High. | East or West.|North or South.|
-----------------------------------------------------------------------------
Northeast|0.23 ft.|0.74 ft.|0.38 ft.|0.00 ft.|0.06 ft. east.|0.04 ft. south.|
Northwest|0.00 " |0.74 " |0.22 " |0.08 " |0.06 " " |0.13 " north.|
Southwest|0.11 " |0.31 " |0.22 " |0.21 " |0.45 " west.|0.13 " " |
Southeast|0.46 " |0.31 " |0.38 " |0.04 " |0.45 " " |0.04 " south.|
=============================================================================

The cost of labor in compressed air chargeable to concreting was $3.40
per cu. yd.

After the roof of each working chamber had been removed, the shield was
erected on a timber cradle in the bottom of the shaft, in position to be
shoved out of the opening in the west side of the caisson. Temporary
rings of iron lining were erected across the shaft in order to furnish
something for the shield jacks to shove against.

The roof of the working chamber was then re-erected about 35 ft. above
its original position and about 8 ft. above the tunnel openings. This
time, instead of the two small shafts which were in use during the
sinking of the caisson, a large steel shaft with a T-head lock was
built. This is illustrated in Fig. 2, Plate LXIV. The shaft was 8 ft. in
diameter. Inside there was a ladder and an elevator cage for lowering
and hoisting men and the standard 1-yd. tunnel cars. At the top, forming
the head of the T, there were two standard tunnel locks.


MANHATTAN SHAFTS.

A permanent shaft, similar to the river shafts in Long Island City, was