27

seating national societies shall be selected by
the said societies in such manner as they may
determine; the
secretary shall be advised of
this selection.’
“5. Members of the Executive Board
repre-
senting local, state and regional organizations
and affiliations shall be nominated and elected
from each of the several districts
by the
rep-
resentatives therefrom on the CouncT, at a
meeting duly called for the
purpose, provided
three fourths of all
representatives of said dis-
trict are present or represented; the selection
sha’l be reported to the Secretary.’’
Making Concrete
Pipe.
In the Hume centrifugal process of manufactur-
ing concrete pipe, as described by W. Wolstenholme
to the South African Institution of Engineers, the
cement is mixed with crushed stone from the Wit-
watersrand mines, and material from the large quan-
tities of discarded mining ropes is added for rein-
forcement. The
ropes, slowly rotated, are cut into
suitable lengths, annealed, unstranded, and then
woven into
cages which are inserted into the moulds
as the skeleton of the pipe. The necessary amount
of concrete being- then poured into the moulds, the
machine is
speeded up, and the centrifugal force
both
packs the solid material evenly and dries out
the water. Six pipes 4to 6 inches in diameter can
be completed in 8 or 9 minutes, four of 15 to 18
inches in 15 minutes, and single specimens of larger
sizes
up
to 60 inches in about 20 minutes. In the
tests made, the pipes below 9 inches in diameter
withstood
pressures of 300 to 350 pounds per square
inch, the larger sizes resisting 210 pounds. At ex-
cessive pressures the pipes do not give way
sudden-
ly, but develop pores and cracks.
Concrete Institute Meeting.
The American Concrete Institute held a sectional
meeting July 16 in New York City, which was called
by President H. C. Turner. W. A. Slater of the U. S.
Bureau of Standards gave a talk in which he des-
cribed a number of the tests on especially designed
beams for the concrete ship section of the Emergency
Fleet Corporation, in which
special attention was
paid to the investigation of shear strength.
27
1' II i; CONCR ET E AG E
October, 1920.
SNEAD ARCHITECTURAL IRON WORKS
LOUISVILLE, KY.
Structural Steel and Ornamental Iron. Large
Stock of Standard and Bethlehem Shapes.
Immediate Shipments Plain or Fabricated Materials.
MARTIN SEMI TRAILER
METHOD OF HAULING
A well-built motor truck can easily PULL from two to three times the weight it can
CARRY. 1 heielore a one-ton truck can easily pull a two or three-ton load; a two-ton
truck a four or six-ton load, etc. The Martin Semi-trailer method of hauling enables
motor truck owners to utilize the entire tractive
power of a motor truck, much of which
•!-'
ordinarily wasted.
ROCKING
ItII
ill
m
wrmm as
Si
ill:
, mm
SEND FOR 32 PAGE
CATALOG GIVING
FULL DETAILS.
ROCKING FIFTH
WHEELS
FLOATING BEAR-
ING AXLES
CASTOR JACKS
REAR END
ASSEMBLIES
SEMITRAILERS
SEMI-TRAILER
PARTS
Note that the Martin Fifth Wheel and Fear End Assembly together constitute a chassis.
MARTIN ROCKING FIFTH WHEEL COMPANY
SPRINGFIELD MASSACHUSETTS