Morning journal and courier., 1890-11-25
THE HIsToRIoAL SOCIETY.

THE HISTORICAL SOCIETY.
An Able Paper ON Bridge Construc-
ton by Professor w. r. Trow-
bridge-InterestinS sketch OF the
Covered Bridge Over Lake whitney
The Society,s Annual Meeting.
The New Haven Historical society held
its annual meeting last evening in the
court Of common pleas room and listened
to an able paper read by Professor William
R. Trowbridge Of Columbia college, on
Historical Notes on the Development Of
Bridge Construction. The attendance
was unusually large; and interest in the
words Of the speaker was marked. The
paper in brisf read as follows:
There are few subjects connected with
the science of engineering that can be pre-
scented to popular audience without the
accompanying risk that the introduction
of technical details may prove uninterest
ing and perhaps wearisome, especially when
topic 80 commonplace as bridge building
Is the subject of treatment. The only
treatment that would at first seem attrac-
| tive would appear to be mere descriptions
of noted or famous structures which have
| from time to time been erected and which
have signalized the worlds progress in this
branch of mechanic arts and the achieve
ments of professional engineers But there
is much besides that is interesting
when we trace the development Of
| this art, which in our times,
more than in any other period
| in history il. felt to be essential to the very
existence of modern, commercial and So
cial intercourse, and without which the
material progress Of the present day would
have been impossible. Many of US can
| toward the sgreat west" could be. accom-
pEshed only by fording the principal
smaller rivers; now we are carried in rail-
way trains across great rivers and deep
chasms with rapidity and safety. The
iron bridge now holds place of common
Importance with the railway, the locomo-
tive and the steamship all linked together
in the modern developments Of CONNER
cial and social movements. We find that
nearly all great bridges Of both type, the
| arch and the suspension bridge, construct
| ed in ancient as well as in modern times
have been regarded with pleasure as en-
| bodying pleasing elements OF architecture.
Another point of view, and one which it
| is the object of this paper to point out
more definitely, relates to the mechanical
| principles involved in bridge construction
and the introduction Of new forms as the
demand has become more imperative for
| larger spans and the rapid transit of
heavier loads.
The history of the development of the
art of bridge construction is thus marked
to certain extent by periods and eras
/ coincident with either the introduction of
new materials in the arts or the necessities
which have arisen for composing greater
spans under the conditions of heavier
1 %,.oA &C. cfr t,,riI onfr
ancient origin has held it's place, though to
| a limited extent to our own times The
reverse of the suspension bridge, the arch,
has held the most universal sway of all
systems until the long spans met with
in the routes of railroad communication
and the difficulties of establishing piers in
swift currents and on tIeacherous founda-
tions brought about first the long span
timber bridge and subsequently the modern
structure in wrought iron. The history of
the arch in bridge construction extends
much further back than the beginning of
the Christian era. Cast iron bridges were
first introduced q little over one hundred
years ago in England and for time met
with marked public favor. It is claimed
that Thomas Paine was the inventor of the
cast iron arch, but this claim is not well
founded, inasmuch as this kind of bridge
was already in use in England before Paine
sailed from America with the object of
carrying hisplans abroad, where he thought
they might be favorably considered. The
cast iron bridge has had, however, but a
brief historical record on account of the
want of sufficient elasticity, imperfection
of castings, and the liability to rupture I'M
der sudden strains or blows.
Of timber bridges, it may also be said
that they have had their day and have full
| filed their temporary uses.
The name destined to the most substan-
tial and enduring fame in connection with
timber bridges is that of Ithiel Towne, for
many years before his death an architect
of New Haven, Connecticut. Two or three
miles out of New Haven there is a covered
bridge spanning narrow part of Lake
| Whitney which, in connection with the
subject which we are discussing, has an
interesting history. The bridge, although
presenting in itself no pleasing artistic
feature, being entirely covered in by
weather boarding, is the central feature OF
ono Of the beautiful but limited little land.
scapes on Lake Whitney; and to the PEG
pie of New Haven, who know its history,
is tho chief object of interest in this par
! ticular spot. Few persons, however, are
, | aware of the fact that the mechanical de
sign of this bridge was the first departure
from the principle Of the arch and the sus
t pension principle ever attempted, and thai
0 It is, although constructed entirely of tim
! Der, without nail or spike except thos,
used in the board covering, the anti-typ'
5 of nearly all modern constructions il
9 iron which have of late years become 8,
numerous, and which are classified as bracet
4 girders. The bridge was devised ana
. erected by Ithiel Towne about the year 1872;
? for the New Haven and Hartford Turnpike
!, company, across the Mill river. 1t is on
4 - L., Co. 10
q twelve feet high, and is built on the prin
q ciple of straight top and bottom chords
! connected by diagonal bracing, principl
a invented by Mr.. Towne, and never befor
a introduced into bridga construction.
I About the year 1850 Mr.. Eli Whitney
. who is now vice president of the Historica
3 society of New Haven, and who was thel
s constructing dam and reservoir on Nil
o river, which now supplies New Havel
2 with water, removed this bridge bodily o.
n skids from the point where it was frs
: erected to the place it now occupies abou
v one-third of q mile distant-a difficult fea
= of engineering at that time, but accom-
e plished without removing or displacing
v single timber of the bridge. The bridg
!. is thus probably one of the Oldest timbe
bridges of any considerable span in thi
or any other country, having fortunatel
escaped the fate of nearly all large timbe
70 Observation-Disclosures by fire.
n The principal parts have never been re
d nswed, and, to the board covering, thes
!. parts are still sound and service
h able But its age is matte
: comparatively unimportant when W
" consider its historic significance at til
4 present time The entirely new principl
4 embodied in its construction was destine
4 to work a complete revolution in the Al
1 of bridge building throughout the worlG
= In but few instances in the history of gres
! inventions do we find the far-reaching n
r. suits anticipated by an inventor more con
% pletely verified by subsequent events. MI
a Towne's bridge was patented in 1890 and i
y 1881, several years after this first bride
was constructed, description of the il
vention prepared by Mr.. Towne himself ws
published in New York.
RI The latest advance in what some woul
10 prefer to call the evolution of the bridge
4 the cantilever system. This system hs
spread with great rapidity during tina pas
l. five years, the great railway bridge acros
o the Firth of Forth in Scotland recentl
constructed on this principle having tn
= extraordinary span of seventeen hundre
e feet, one hundred feet greater than that {
u u the New York suspension bridge.
FL The most ancient bridges of which "
have any precise knowledge were built b
the Romans, all those of permanent cha
acter having been arched masonry bridges
1t is certain, however, that such bridge
- were built in China many centuries agt
.. but of their history little is definitel
"a known. In England tho Oldest bridge +,