Brunel’s failed invention

One of the greatest inventions of the 19th century, and of all man’s time, has yet to be developed. It failed initially for a trivial reason which, today, could be easily overcome. When it is finally embarked upon, it will change the physical infrastructure of many countries to such an enormous extent that we can’t possibly imagine all its ramifications. Its development may still lie a century in the future, though there’s no reason why a particularly enterprising culture such as Singapore or Switzerland or Israel shouldn’t start planning it tomorrow.

I’m reminded of the invention every day as I sit at my keyboard and look out of the window. Yet, to my complete surprise this morning, I realize that I have never written about it before now. A group of trees about 100 yards ahead of me is the prompt. This at is the beginning of one of the first tunnels of the Great Western Railway built by the engineering genius, Isambard Kingdom Brunel in 1833. It’s still in use today. If I listen carefully at various times in the day I can hear the low rumble of a London-destined train approaching along a deep tree-lined cutting. The sound then vanishes. If I walk to my back garden quickly I can hear the sound again as the train emerges from the tunnel about 200 yards away to the east. (My house doesn’t actually sit over the tunnel, thank goodness!)

Brunel’s first idea was that his Great Western Railway should be pneumatic — that is, driven by air pressure. It would be so much more efficient than the locomotive system than was then being used to pull carriages and freight trucks along. Instead, in Brunel’s experimental version, the leading carriage or truck had a short downward extension on which there was a circular piston which snugly fitted inside a 12 inch wide tube with a slit along the top to allow forward motion. A steam-driven pumping engine a mile or two ahead pumped out the air ahead of the train. The air pressure behind the train would then push the piston forward — and at very high speed, too. The slit in the tube was was covered by a continuous leather strap which slid aside briefly as the piston-arm moved along the tube and then sealed over again when the train was past. Brunel tried it out. He demonstrated conclusively that a pneumatic railway was, indeed, much more efficient than a locomotive driven railway (in which heavy steam engines) have to travel almong as well as the freight.

The problem with this experimental model — which Brunel hadn’t foreseen — emerged within weeks. This was that countryside rats took a liking to the leather valve, nibbled away at it and thus rendered the tube less than air-tight. This dashed the whole project. There were no rubber-like or plastic materials available in those days which were rat-proof and could have been used instead of leather. Thus, Brunel had to revert to the conventional method of mobile steam-engines pulling the train for his Great Western Railway. Another way of overcoming the problem was theoretically possible. This was to construct a much larger tube so that it fitted snugly around the whole front of the leading carriage or truck. This would be even more efficient. But the cost of building a tunnel for the whole distance of 110 miles between Bristol and London was far beyond the pockets of the GWR Board of Directors.

However, to show that this method was feasible, a full-tunnel short-length fun version was built in the grounds of Crystal Palace in 1864 to the delight of hundreds of people who tried it. Also a short-length passenger railway (with serious intent this time!) was constructed under Broadway in New York. Once again, however, this proved to be unfeasible because of lack of suitable sealing materials. In the 1960s, some Lockheed engineers designed a pneumatic system for a Boston-Washington commuter route. At the same time, the Swiss were considering a pneumatic metro system between their major cities. But in both cases it was cost, not method, that stopped further consideration.

However, the cost could be much further reduced by a cut-and-cover method of construction whereby, for most of its length, the top soil is replaced over the top of the tube and the normal amenity or agricultural value of the countryside is resumed. The overall cost would also be reduced substantially if large factories and warehouses (both increasingly automated with smaller numbers of personnel) were integrated with pneumatic railways with countryside above them all. Freight containers could be rolled on and off vessels at the ports and imports delivered at regional warehouses within an hour or two even in large countries. The cost of land-freight could be reduced to levels scarcely more than those of sea transport today. Countries without coastlines would not be as disbenefited as they are now. As for commuters, the time spent every day could be reduced to a fraction of that by car or existing railways.

I gave a talk about this to the Bath Royal Literary and Scientific Society about 20 years ago. A friend told me afterwards that I’d given the talk in a flat, unexciting way. That surprised me but perhaps I did. If so, the reason was probably due to the fact that I then still considered Brunel’s invention to be premature. If the Swiss had decided against it for cost reasons in the 1960s then it was still probably not the time for it to be taken up in the 1990s. But there is a difference today which is beginning to be discernible as part of our credit-crunch problem and forthcoming recession. This is that there is no great chain of new consumer products ahead of us which existed all through the past 300 years and served stimuli for economic growth. If there is to be economic development (measure in conventional terms) then it’s going to come via new efficiencies on the production side and not new consumer gew-gaws. Also, if we add in the desirable restoration of a great deal of our countryside, then Brunel’s invention is surely going to be one of the answers one day.

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