No. 6

Excavation Completed. ]

Temporary raker braces were placed against the structure to prevent lateral
movement. Four sets of these temporary shoring girders were used in this
manner, two sets starting at the north end and two sets at about the middle
of the work, and these sets were moved south as they were released.

The columns being thus supported on temporary shoring girders, the old
foundations were removed and the excavation was taken down to a level about
16 ft. below the surface.

Two sets of three of the girders "C" were then put in place under the
avenue at each column, each set being placed on four concrete piers 6 ft.
square with spaces of 4 ft. between them, so that the outside of the
outside pier would be 18 ft. from the center of the avenue and 32 ft. from
the house line. This is shown on Fig. 5 and on Fig. 3, Plate XLVII. Four
small piers were used, as they could be more easily removed than one
continuous pier. The girders "C" were set to line and grade, and the piers
were built under them, great care being taken to get the concrete well
under the girders so as to give a firm bearing.

After these girders "C" were in place it was necessary to remove the
temporary shoring girders before the bents could be erected on girders "C"
to support girders "B," being in the same plane; and provision had to be
made to support the structure while this was being done. Therefore, double
bents were erected directly beneath the columns, as shown by Figs. 2, 4,
and 5, and by Fig. 3, Plate XLVII. These were built with their sills
resting on the girders "C," and blocking was put in between the sills and