New-York tribune., 1878-03-02

foN5 %IhH %
IYArr 4to, PIP 90 Chiswick Press, London Printed
for private circulation.
This essay opens with a severe but just
criticism upon previous methods Of using iron in 80
called frc-proof construction defective, because the
lower fanye the left naked and exposed
to fame while it is admitted that the hange ls the Tie
upon which the integrity Of the beam depends.
In the of a series OF experiments III
covering hauges, Mr. Hyatt found that the strength
and the frc-ressting property Of the beam could
be very largely increased 10y incloslng II con-
plctey III concrete; or rather, by substituting
beam Of concrete with The spaces between
these beams DO not need to be wholly hicd with con
crete; fact, owing to the greater security OF such
beams as well their ncrased strength other portions
Of "A fre-pIoof structure may he considerably ghtened
Further experiments showed that the composite beam
could be made OF surprising strength when only The bot
tom hange OF tie iron retained the rest Of the metal
being wholly removed. Peculiar devices were used 20
secure and tie the iron, both at the euds and at inter
vals so that the metal heated should not slip in the
concrete. Also peculiar Kind Portland cement
empoged, which formed more perfect union with the
iron than had hitherto been attained. The experiments
tested these composite by furnace heat and by
LOADING to a king strain. The results, detailed aud
tabulated, appear to prove that by such methods,
in a majority Of architectural structures, great
Improvement in strength, lightness aud fre-proOf
proppIties be secured without increased cost.
The book IS freey illustrated with diagrams showing the
methods Of using tho composite beams in different
strucureF but all the principle is adhered TO- Of
surrounding the iron with enough fgeprooi material TO
protect 1t.
The saving tiat may be attained in the amount
of IRON by using the composite beam, is remark
able The following is Of the comparisons: it was
shown that wrOuglt-rOn Deam ten inches deep with
bottom Gsnge of two by one-quarter inches, and
encasnd in concrete beneath. sustain breaking
strain OF only s272 pounds. On the other hand Mr..
Hyatt uses only the bottom ange OF the iron puts row
vertical 1t 10 keep It's place in the concrete
covers with concrete 10 protect the iron entirely,
aud finds this composite beam. in an average OF experl
meDts strong enough for breaking strain Of 1882
pounds besides bearing its additional weight OF con-
crete About hfty composite beams weighing from 200
10 pounds apiece broken in the testing press
Further trials also made by heating in furnace
slaD containing composite beams arranged rep
resent the section a ioor The kept at glow
ing reduess for five hours and then "a Of cold
water WAS Immediately turned upon 1t. This severe
experiment left the slab unDjured The detection dur
ing firing was three-cighths Of inch. but the slab
Strengthened when cold and in second experiment
found capable OF bearing its original load The thick
ness Of cement above the iron, well as below IT, was
three inches Mr. Hyatt not 10 be aware that the
ordinary Portland been superseded at least
IN this country by re-proof cement formed OF lime
Of Tell plaster Of Paris and other ingredients which