intervals, and there was no clogging of the drains whatever. This method
of keeping the drains open was adopted and used successfully for the entire
work. The abutments were built of concrete, and the mixture was 1 part of
cement, 3 parts of sand, and 6 parts of broken stone.

The concrete was mixed in a No. 3 Ransome mixer, and was placed very wet.
No facing mixture or facing diaphragms were used, but the stone was spaded
away from the face of the wall as the concrete was laid. Chutes were used
inside the form, if the concrete had to drop some distance. Work was
continued day and night, without any intermission, from the time of
commencement to the time of completion of each section.

The face of the concrete wall was rubbed and finished in a manner similar
to that used on the walls between Ninth and Tenth Avenues, as described
later.

Fig. 2, Plate LII, shows the east and central portions of the south
abutment, completed and carrying the permanent viaduct, and the excavation
completed for the west portion.


WORK BETWEEN NINTH AND TENTH AVENUES.

_General Description._--The work involved the excavation of about 5.4
acres, between the west house line of Ninth Avenue and the east house line
of Tenth Avenue, to an average depth of about 50 ft., the construction of a
stone masonry portal at Tenth Avenue leading to the River Tunnels, and the
construction around the site of the concrete retaining and face walls.

The following estimated quantities appear in the contract: Excavation of