If building the railway between Cobourg and Peterborough was the most important event of Cobourg's history — as I, for one, would be prepared to argue — then the faulty construction of the bridge is the most important element in that history's sorry outcome. I would hold that, in the end, Cobourg impoverished itself and remained a relatively sleepy, if elegant, backwater, for the next hundred years because of that bridge.
Had the bridge not been proposed, Cobourg would not have sunk so much money into its town hall (see current photo), which it didn't manage to pay off until the 1930s. Had the bridge not failed so spectacularly and expensively, Cobourg may actually have gotten a good few years of profit out of its railroad.
That profit may in turn have accrued to Cobourg, rather than disappearing into the coffers of American steel barons, who paid Cobourg back by building magnificent summer homes here while avoiding paying those taxes which would have strengthened the town's infrastructure.
But we are ahead of ourselves here.
It was a very costly bridge.
We must remember, though, how justly proud of it the Cobourgers were.
Let us listen, briefly, to Catherine Parr Traill (photo
below). In an essay called, A
Walk to Railway Point she writes (probably viewing the work
from the current road just west of Harwood):
"The eye follows the line of posts, four abreast, which stretches in leviathan length far, far across the rippling waters of the lake. There... is the mighty machine that looks in the distance like a tall gibbet (the pile driver)."
She then describes the honest yankee who is the foreman and proceeds
"It is curious to see the log of timber, some twenty-five or thirty feet in length emerge from the depth of the lake... it seems to come up like a huge monster of the deep, and rearing itself by degrees, climbs up the side of the frame like a living thing;"

The log is positioned and
" ... clack clack clack goes the little engine on the scow:
slowly aloft mounts the great weight, down down down it comes - the
first blow fixing the timber in its place - and sends a shower of bark
flying from the pile...."
The weight is borne up again and again descends upon the pile
"with unerring aim — lower it sinks, and every fresh blow comes
with accelerated force, 'til it is brought to the level of the others. From
a quarter of an hour to twenty minutes is the time employed in sinking each
of these posts."
Like anyone who had emigrated to Upper Canada in the 1830s and had experienced the almost non-existent roads and the terrible hardships of the endless forest, she was fascinated, even mesmerized, by this example of how the new age of machinery could conquer such a wilderness. There did seem no limit to what these Canadians could do. Yet, as in all railway stories, there is a price to pay and 14 German laborers paid it with their lives, probably of cholera. Their monument can be seen a mile outside Harwood on the main road.
By mid-May of 1854 the track had been sufficiently laid to Harwood that a delegation of Peterborough worthies were invited down by steamer to meet the train at the ferry docks there. From there they traveled the road down to Cobourg for a grand celebratory dinner at the North American Hotel.
The railroad was still in the hands of the contractor (he would turn
the road over to the company only when it was complete) but the company
began using it anyway on an ad hoc or as needed basis. Proudly they proclaimed
that 1,970,000 feet of lumber passed through Cobourg harbour in one month
that summer, to say nothing of receiving some $600 in passenger traffic.
By the end of the year the bridge and track to Ashburnham, just outside
Peterborough, were finished to the extent that Zimmerman let the company
have nominal control for a week in order to stage a gala celebration
in Peterborough. On the twenty-ninth of December the railroad offered
a free ride from Cobourg to Peterborough for the party. Twelve flatbed
cars had benches nailed to the floors to provide transport for the guests
and little else — except perhaps whiskey for warmth. One can imagine
the first reactions on the part of the passengers to the smoke, the lurching
back and forth and the cold of the apparently swift travel. Probably
more apparent than real, as one guest is known to have wished them well
and then set off on foot to ensure himself a good seat at the banquet
hall in Peterborough.
The banquet was a success. William Weller, past-president of the company,
made a terrible pun on his name:
"You know I get my living running stages, and
now you are taking the bit out of my mouth, as well as my horses' mouths.
All here tonight can recall having to carry a rail, instead of riding
one, to help my coaches out of the mud. But, after all, I am rejoiced
to see old things done away, and new things becoming Weller."
The president Thomas Scott, with by now predictable hubris, declared that they wouldn't rest until "... we have driven the iron horse to the town of Peterboro' on the west side of the river and stabled him there; and even then Sir, he will not, he cannot, he must not rest easy until he has reached..." Chemong Lake — with the usual implication that they could cross that as well if they felt like it.
Three days later the bridge collapsed.