grade of the projected tunnels, these depressions being
separated by a rock reef which extends down stream from Blackwell's
Island. In 32d and 33d Streets in Manhattan, borings were made from the
river to the station site at intervals of about 100 ft., wash-borings
and core-borings alternating. In Long Island City, where the tunnel
lines were to pass diagonally under the passenger station building and
passenger yard of the Long Island Railroad and under streets and private
property, the arrangement of borings was less regular, although the
alternation of wash-borings and core-borings was carried out as far as
practicable. After the final location of the work, additional borings
were made, particularly on shaft sites and also along the approaches and
in the Sunnyside Yard, Long Island City.

A triangulation was carried across the river with a measured base on
each side. It was impossible to measure directly between the extremities
of either base. The bases were measured with 100-ft. steel tapes,
supported every 20 ft., stretched with a uniform pull, and frequently
compared with standardized tapes. On account of the crowded condition of
the streets during the hours of daylight and evening, most of the work
was done between 10 P. M. and 5 A. M. Similar measurements were made in
the streets along the tunnel lines. Angle readings were repeated many
times, as is usual in such work. Fig. 1 shows the triangulation, the
street measurements being omitted.

Levels were first transmitted across the river by simultaneous
observations of the river surface; then by several repetitions, across
Blackwell's Island and the narrow channels on each side, where the
longest sights were about 1100 ft.; and, finally, by several lines
through the tunnel of the East River Gas Company at 71st Street.

The franchise granted by the City of New York provided for the sale to
the Railroad Company of the portions of 32d Street between Seventh and
Eighth Avenues, and between Eighth and Ninth Avenues. Later, the Company
acquired by purchase the portion of 32d Street between Ninth and Tenth
Avenues. The franchise granted sub-surface rights under streets around
the station site to within 19 ft. of the street surface under Seventh,
Eighth, and Ninth Avenues; to within 30 in. of the street surface under
31st and 33d Streets, except that, under the sidewalks opposite the
station, that is to say, the south sidewalk in 31st Street and the north
sidewalk in 33