New-York tribune., 1868-02-15
FDUNDATION5.

The Hon. William j. McAlpine addressed
large ana nppreciatiyc audience ON Thursday evening"
In the LecturcRoom OF the American Institute, on the
subject OF Foundations" lie commenced by quoting
the words Of an eminent engineer and author; The per
manence q engineering structures depends almost en-
trely on the In which their foundations are la
when these are properly made the superstrucure is
more a matter " aste than OF skill" foundation
which gives uniform support proooroned to Its weight
imposed. Ia valuable an nnyeldng one and Is gen
ernly very much cheapr Nheh on r0ck ~ rr,nrs m
the unequal cOmpacNg 81 the foundaion-whu' nnu
hard earfn. when saturated may n-o ye1u ~ n9r a1ada
and when this cannot be Effected Win the mas3rfy
snbstrntum Is very soft bearing gplles driven
not. rs Is popularity believed. TO extend the sup sup
around them; next 10 rock. they furnish the
most Trustworthy support when pLoperB Nv H'Issh pon
showed that the effect 81 Increasing tho weight oI me
hammer was to increase tns "mec' ol ~, .ne a~a yt
and that the sustaining power OF piles oi duecnt Hle
asn Wh W me 'S OF te sp@es These rules en-
able the constructor TO proportion me nze or "
wooden piles alternately VET and dIy; in seawatsr.
ought to he used In these eases hollow iron ples
1sed viii IN not eorrode even IN The most exposed places
Ia centuries Such piles are now standing ~ many
places Europe, which. after the lapse OF nearly hall
century care "a sound when they left the ioundory
when cor0sion In such places II Is wholly due 10
roson often times witnessed In waterplpes Il owing to
the fact that they frequently made OF the worst
quality OF iron. A vast number OF bridges aud other
Structures In Europe are supported upon Iron piles some
Of which but few inches la diameter ana
from that sire up TO twenty feet. They nave hech
made cylindrical eptcal. aud rectangular. and have
been driven by the pneumatic aud hydrosate processes
aud Oftentimes by direct excavation within ~ thls
country the former has alone been used Du the
Others when practicable are much the cheapest when
rocks or logs encountered the pneumatic process be-
comes necessary and columns OF not less than 80 Inches
must 6e used In these cases they are
iutO speces OF diving bell In Europe they have been
driven TO nearly hundred feet below the water ana IN
country with pressure equiyaeDt 10 uept OF -
feet water The wOrknen peTence 10 Inconvenience
al these great depths and really perform more labor than
ln open air. consequence OF the exharaton Produced
by breathing such highly condensed arr inese colnns
are usuay uIade Of castrOn but are sometimes male Ot
iron, and maybe Of wood. In the former the
weight OF the structures IA usually carried on the iron
shell In the latter I"C ney a earpr the load The
shell being used as Golfer Dam or eassoh
These iron piles or columns allow the engineer 20
found his works with safety. ease, anu economy,
in places where wooden plesare nadmlssaDe In wafer
waya with strong currents wooden piles afe usae Tor
liable 10 be destroyed by the teredo For bridge piers
iron columns offer much ess obstruction than those of
masonry. Unlike the wooden piles they derive their
chief support from the OF their bases ana modern
permits these TO he rebled at an i-
expense, and, consequently enhples the u
ameter 70 be reduced that merely OF q column OF
rail way tracks 10 supported on Two columns ior ec
pier eight feet diameter and the Chepstow bridge with
double track three columns of sx feet diameter ana
ilO feet high and IN number OF bridges In Europe and
our country the draw piers eonsists 0i cluster OF
such columns The pers consisting OF par % Vt e1o @
pact heavy vessels and very large masses OF Ice and
drftwoOd resistance TO the Influence OF the mos.
and the high latitndss NJ Northern Russia In different
places piles piers be built much cheaper than
stone piers wooden piles In many places with no more
expense and In others they aord the only safe fouda
ton AT tile close Of Mr. MoApnes address, many OF tho
points alluded 20 we're discussed briefly.