Arizona republican., 1905-10-19
BIGGEST DAN ON EARTH
A Technical Description Of the Tonic
Project.

The most complete and readable
story Of the building of the Tonic re-
servoir appears in the current num-
Der of the Technical World Magazine.
The author is Crittenden Marriott of
the staff of the United States geolo-
gicaI survey. The story is copiously IL
Illustrated including first a general view
of Salt river, the diamond drill work
in boring at the dam site, an elevation
of the dam. a horizontal plan of 1t and
a section of the plan and elevation of
spilIway and power house. There are
photographs of Mr.. Newell and Mr..
Davis at work in the field, view of
the abutment wall of the dam and then
an example of furrow irrigation near
Phoenix There is one picture which
either indicates that Mr.. Marriott did
not understand a familiar scene III
Phoenix or else that he was inclined
to be facetious There is a group Of
squaws each bearing an ola on her
mead. This aggregation is described
as the Phoenix water works"
The actual beginning of construction
work in June of this year on the dam
described by Mr.. Marriott as the
Greatest Dam on Earth is regarded
by him as a peculiarly fitting celebra-
ton of the third anniversary of the
adoption of the reclamation act. He
says there are other great reclamation
works in various stages of preparation
but no other of such a stupendous
character is in actual progress. Mr..
Marriott describes the three years ar
duous work of preparation and then
gives the following comparison Of the
size of the Tonic dam with other great
retaining structures: Fifteen years
ago the highest dam in existence was
height of which was 10 feet. Since
then three very mucn larger dams have
been built in the United States. These
are the Croton dam in New York, the
Clinton waterwOrks dam at Boston and
the water works dam at Denver on the
south fork of the South Platte river.
Each of these at present holds the re-
cord in one respect or another; the
Denver dam is the highest in
the world; the Clinton i'm
pounds the most water and the Croton
dam contains the largest mass of ma
sorry. But the Salt River dam will
exceed each of these in its own spe-
ciaIty. It will be higher than the dam
at Denver; it viii exceed the CrOtOn
dam in masonry and will impound
twice as much water as all three dams
put together. It will be 27O feet high
from foundation to parapet, win con-
tain 300 900 cubic yards of masonry
and will impOund more than a million
acre feet of water-that is more than
enough to cover a million acres G,5OO
square miIes) to a depth of one foot"
Mr.. Marriott mentions the interesting
fact that the real work Of preparation
for the building of this great structure
began thirty years ago for though the
government appropriation for the mea-
surement of the river was made only
four or five years ago reliable mea-
surements extending back for thirty
years mad been made and the records
were available for the later work of
measurement.
On the subject of measurements Mr..
Marriott says: This exactly right
dam could be fixed only by an init
mate knowledge of, not only of the
quantity of water each height of dam
would hold but also a close approxima-
ton of the quantity of water that
would be available to fill it. To learn
this, measurements of the flow of Salt
River and Tonic creek extending over
several years were necessary. Guess
work based on the mere eye is worse
than useless in the case of arid land
rivers. During one year the river viii
be flooded one month and bone dry an
other; in a second year there Will be
plenty of water all the twelve months
while on a third the supply will be
limited even in the rainy season. The
danger of guessing was illustrated by
a dam built without proper measure
ment in Mexico a few years ago The
engineer was assured that the supply
was ample and was asked to rush the