14 Holiday specials The Economist December 18th 2021
ture, the 2,200 squarefoot (204 squaremetre) Tur
pentine Shed. It was the world’s first corrugatediron
building. Its halfbarrel roof soon became emblematic
of building with the material. Admirers had no doubt
of its radical nature. One, in the “Register of the Arts
and Sciences”, deemed the Turpentine Shed’s roof to
be “the lightest and strongest roof (for its weight), that
has been constructed by man, since the days of Adam”.
Palmer’s largespan roofs found ready use on naval
slipways, where ships had hitherto been constructed
in the open. Corrugated iron also enabled the grand
new termini of the burgeoning railways. None was
more impressive than Paddington station, built in 1854
by Isambard Kingdom Brunel. It remains unchanged,
in essence, even today.
Rust was corrugated iron’s first problem. Galvani
sation—coating it with corrosionresistant zinc—was
the solution. By the mid19th century Britain’s galva
nising industry was using 10,000 tonnes of zinc a year.
When, in 1856, Henry Bessemer created a revolution
ary furnace that blew air through molten iron to drive
out impurities and create steel, the demand for galva
nising grew further. Steel is more formable and ductile
than iron, and stronger. It is also more prone to rust.
Around the middle of the 19th century, a more
democratic impulse came to embody corrugated iron.
It emerged, oddly, with a royal nudge at the Great Exhi
bition of the Works of Industry of All Nations. One of
the defining events of the time, it was held in 1851 in
Crystal Palace in London’s Hyde Park. A third of Brit
ain’s population flocked to it. The exhibition was in
tended to showcase the wonders of the industrial age.
Queen Victoria’s consort, Prince Albert, was the ex
hibition’s chief patron. Among all the exhibits, homely
Albert was struck most by an emigrant’s corrugated
iron cottage. He ordered something similar for Bal
moral, the royal residence in Scotland. Just weeks later
it had been fabricated, shipped and erected. Today, it
serves the estate as a carpenter's shop.
Albert’s blessing spurred the trade in portable, tim
berframed, corrugatedclad buildings. Also helping
were the early gold rushes of California (1848) and Aus
tralia (1851)—where this “universal material” really
came into its own. Within a year of gold being found in
New South Wales and neighbouring Victoria, 500,000
immigrants were scouring the land for new finds. Brit
ish manufacturers rushed to provide shelter. Shipping
firms exporting wool from Australia to Europe gladly
took cargoes of corrugated iron on the return trip. Im
migrants to Australia often shipped their own prefab
homes with them. South Melbourne’s “Canvas Town”,
a shanty encampment of prospectors and traders, ac
quired a more permanent air thanks to corrugated
iron kits for cottages and shops arriving on the quay.
Land dealings on the new frontiers of Australia and
New Zealand were notoriously dodgy. In case of evic
tion, having a portable house was a distinct advan
tage—you did not lose everything. Thanks also to
cheapness, portability and a relatively rustfree cli
mate, “wrinkly tin” blazed across the frontier land
scape of the Antipodes. From kennels to post offices
and even the outdoor dunny, there seemed nothing tin
could not do. In urban settings, tin cottages gave way
to bungalows with verandahs, and then structures of
two or more storeys. In New Zealand tin was given a
new lease on life in 1936, with the fixing of a 40hour
week and two days out of every seven for leisure. Thewrite Adam Mornement and Simon Holloway in their
terrific book on the stuff, “a material of the frontier”.
Consider its ubiquity. Water butts, bird hides, out
side latrines, aircraft hangars, aircraft themselves, wa
ter towers, lighthouses, the abandoned whaling sta
tion of Grytviken on South Georgia and, most haunt
ingly, places of human internment, be they for refu
gees, prisonersofwar or the persecuted: corrugated
iron has loomed large. In Mawsynram in northeast In
dia, which receives the highest rainfall on Earth, build
ings cannot be of wood, for they quickly rot; the sound
of the Mawsynram climate, then, is the ratatattat of
huge raindrops falling on “tin”, as the material is wide
ly referred to. Tennessee Williams knew what meta
phor he wanted for the enervated sexuality and jittery
frustrations of Maggie, one of his bestknown protago
nists, in a doomed marriage—“Cat on a Hot Tin Roof”.
Corrugated iron is a child of the Industrial Revolu
tion. The bestknown origin story starts at the Phoenix
ironworksnear Birmingham, when a sheet of metal
serving as a guard protecting workers making rails
worked loose and got pulled into the gears of the
machine. While the workers fabricated a new guard,
John Spencer, master of the ironworks, picked up the
crumpled sheet. It did not flop around or bend under
pressure as sheet metal usually did.
Spencer had stumbled upon how a linear pattern of
ridges and furrows renders a sheet stiffer perpendicu
lar to the axis of the corrugation. The scientific expla
nation for this lies in the, to laymen, nearly inscrut
able Theorema Egregium(Remarkable Theorem) of Carl
Friedrich Gauss, published in 1827 and concerning the
curvature of surfaces. More intuitively, consider a
common pizzaeating strategy: gently bending your
slice before bringing it to your mouth obviates the risk
of buckling and consequent mess.
Spencer envisaged a machine in which sheets were
fed through a pair of grooved rollers. Thus was the bar
rel corrugator born, a thundering machine that served
as the chief way to make corrugated iron until the sec
ond world war. But the earliest patent was registered in
1829 by Henry Palmer, an architect and engineer with
the London Dock Company. Palmer's insight was that
while possessing transverse strength, corrugated
sheets can still be curved lengthways and then lapped
and riveted to form a selfsupporting arch. Such a roof
would be light. But in the same way that the shell of an
egg represents impressive structural strength, it
would be capable of bearing compressive forces pre
sent in all roofs as their weight bears down with grav
ity on whatever is holding them up. Up to a certain
span a corrugated roof of selfsupporting sheets can
arch across a given space with little or no recourse to
the usual supports used to hold up roofs clad in slate or
other heavy materials. Suddenly, sheds far larger than
had previously existed became imaginable.the world’s entrepot
Towards the end of the 18th century, London was the
victim of its own success. The River Thames was
choked with vessels from around the world waiting for
a limited number of wharves. Work on a new London
Dock began in 1800. But by the time the 32yearold
Palmer was hired in 1827, the London Dock was burst
ing. A new basin, locks and warehousing were needed.
Palmer would oversee the work.
In 1829 he proposed a large and new type of strucCorrugated
iron is a
child of the
Industrial
Revolution