of the East River Division. The borings had shown a great variety of
materials to be passed through, embracing quicksand, coarse sand,
gravel, boulders, and bed-rock, as well as some clayey materials. (See
Plate XIII.) The rock was usually covered by a few feet of sand, gravel,
and boulders intermixed, but, in some places, where the rock surface was
at some distance below the tunnel grade, the material met in tunneling
was all quicksand; the nearest parallels in work previously done were
some of the tunnels under the Thames, particularly the Blackwall tunnel,
where open gravel was passed through. Before the plans for the East
River tunnels were completed, work had been resumed, after many years'
interruption, in the old Hudson River tunnels between 15th Street,
Jersey City, and Morton Street, Manhattan, and sand materials were
passed through for a short distance. These experiences satisfied nearly
all the engineers in any way connected with the work that the shield
method was the most suitable for the East River tunnels, and the plans
for the work were based on its adoption. (See Plate XII for
cross-sections, etc.) Other methods, as stated by General Raymond in the
introductory paper, were advocated, particularly caisson constructions
and the freezing process, the latter being urged very strongly, and,
when proposals were invited, in October, 1903, bidders were informed
that alternative methods would be taken into consideration.

Bids were received and opened on December 15th, 1903. Only one bidder
proposed to carry out the work on the basis of unit prices, but the
prices were so low that the acceptance of the proposal was deemed
inadmissible; no bid based on caisson methods was received; several
offers were made to perform the work by the shield method, in accordance
with the plans, for a percentage of its cost, and one was submitted, on
a similar basis, covering the use of the freezing method. The firm of S.
Pearson and Son, Limited, of London, England, submitted a proposal for