Friday, April 14, 2017

Archimedes Back To Life

Outside the rural English village of Anderton, two navigable waterways pass within touching distance of each other. At least, they would, were it not for a fifteen-metre altitude difference. The higher of the two is the Trent and Mersey Canal, which opened in 1777, and enabled goods to be transported, via a basic chute system, down to the lower-lying River Weaver, and vice versa. The principal commodity for export was salt, which had been extracted from beneath the Cheshire Plain for centuries; whereas imports included copper and tobacco.

In 1793, the waterways’ respective owners concluded that the transfer mechanism was grossly inefficient. Consequently, Chief Engineer Edward Leader Williams (1828-1910) began to design a boat lift, using twin caissons (water baths), suspended by chains, to transport cargo boats. As one caisson descended, the other would, in perfect counterbalance, move upward. As with any application of hydrodynamics, Williams’s design had the name Archimedes engraved throughout. Imagine a salt-laden boat, weighing sixty tons, down on the riverbank. Now consider the two vast metal caissons, each holding an identical mass of water. As the boat enters the lower caisson, it necessarily displaces its own weight – whatever that might be – and always retains counterbalance with the higher caisson, whose water load never, therefore, requires adjustment. In a word: ingenious.

Williams employed hydraulic engineer Edwin Clark (1814-1894) to design the structure. It was initially powered by a steam engine, 10 horsepower (7.5 kW) being sufficient to raise a caisson in just three minutes. Construction was approved in 1872, and the first cargo transported three years later.

Thereafter, design faults soon became apparent. Cast iron structures were susceptible to bulk fracture; displaced salt caused rapid corrosion; and freezing temperatures would bring work to a standstill. In 1904, another hydraulic engineer, Colonel John Arthur Saner (1864-1952) redesigned the lift, replacing steam with a modern electric motor, which trebled the available power.

The lift operated successfully until the 1960s, when canal commerce was superseded by the superior logistics of road and rail. In 1983, the lift was finally closed, owing ultimately to severe structural corrosion and general neglect.

But for the tireless campaigning of local trusts and heritage associations, the lift would probably have been demolished, and its glorious history forgotten in time. Funds were raised, remedial work began in 2000, and the lift reopened, against substantial odds, in 2002 (Figures 105.1, 105.2 & 105.3). Anderton’s showpiece remains the only working boat lift in England – and the oldest.

Figure 105.1: Today, the lift is fully functional and computer-controlled.

Copyright © 2017 Paul Spradbery

Figure 105.2: The entire site has been rejuvenated, with tasteful landscaping, outdoor picnic areas and viewing platforms on both levels.

Copyright © 2017 Paul Spradbery

Figure 105.3: The twin caissons, photographed from the canal basin

Copyright © 2017 Paul Spradbery

I took my youngsters for a visit last weekend. There is a spacious twin-level visitor centre, both indoor and out, with a range of interactive exhibits and a smart café. Best of all, there are commentary-assisted narrowboat rides (Figures 105.4 & 105.5) along the river to the nearby town of Northwich, ending with a smooth ascent inside a water-filled caisson (Figure 105.6) to the restored aqueduct above (Figure 105.7).

Figure 105.4: Who needs a Mississippi paddle steamer?

Copyright © 2017 Paul Spradbery

Figure 105.5: Introducing Mel, the impressively knowledgeable tour guide. Here, she is explaining the lift’s history, despite appearing to be singing karaoke.
‘Don’t rock the boat, baby … don’t tip the boat over …’

Copyright © 2017 Paul Spradbery

Figure 105.6: The boat entering one of the caissons at the lower (river) level …

Copyright © 2017 Paul Spradbery

Figure 105.7: … and emerging at the higher (canal) level

Copyright © 2017 Paul Spradbery

As the boat sailed leisurely into town, I looked upward, through the glass roof, and noticed a lone buzzard, riding the thermals, its wings outstretched and motionless in the afternoon April air. It was simply utilizing the natural dynamics of the physical world. The Anderton Boat Lift does likewise, and all because a group of brilliant British brains, led by Williams, Clark and Saner (Figure 105.8), stood on the shoulders of a Greek giant – and got their sums right.

Figure 105.8: This striking outdoor mural, courtesy of artist Diana Bernice Tackley, depicts Sir Edward Leader Williams (left), Edwin Clark (centre) and Colonel J A Saner (right).

Copyright © 2017 Paul Spradbery

Copyright © 2017 Paul Spradbery

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