Avenue. The number
of teams was not sufficient, therefore, to keep the three shovels busy
when they were all in good digging, but the dumping board was taxed to
accommodate that number, and little would have been gained by increasing
it. The digging was very good during this period, practically no rock
being encountered, and the building foundations were too light to
present any obstacle to such powerful shovels. The capacity of their
dippers was 31/2 cu. yd., so that one dipperful meant one truck loaded and
running over. The output from August to November, inclusive, averaged
40,000 cu. yd. per month; one shift only was worked per day, and
although the quantity was not large for three such powerful shovels, it
was large to truck through the streets, and required that one team pass
a given point every 18 sec. At the end of November the opening up of
the pit had been accomplished, considerable rock had been stripped
near Ninth Avenue, and the streets had become so icy that the cost of
transportation was practically doubled; work in the pit, therefore, was
much curtailed, and amounted to continuous work for one shovel from that
time until the end of the period, May 22d, 1905, when Pier No. 72 was
put in service and transportation by train began. Figs. 2 and 3, Plate
LVI, show the condition of the pit east and west of Eighth Avenue,
respectively, on that date.

[Illustration:
Fig. 9.
SKETCH SHOWING TYPICAL BENT OF TRESTLE SUPPORTING EIGHTH AVENUE]

The work of excavating for and building the temporary street bridge,
a typical bent and bracing for which are shown on Fig. 9, and the
cast-iron sewer and water mains in Eighth Avenue, was commenced on
September 3d, 1904. The trestle was a double-decked structure of yellow
pine, with 10 by 10-in. posts and sills, 10 by 14-in. intermediate and
top caps, and 2 by 10-in. longitudinal and cross-braces. The trestle was
further stiffened longitudinally by four lines of 8 by 10-in. struts,
butted between the intermediate caps, and held in position by 2 by 8-in.
splice-plates resting on top of them. The intermediate caps were at an
elevation of 15 ft. below the surface of the street, and above that line
the longitudinal bracing was continuous, while below it the bents were
braced in pairs, the bracing being omitted from every second bay. Below
the intermediate cap the bents were uniform for the entire width of the
trestle, but the top cap was not continuous, being 5 ft. below th