November 1861: Chalmers' under Channel railway | Hacker News Reader

November 1861: Chalmers' under Channel railway

theengineer.co.uk

23 pointstimthorn9 comments

> Tunnels and bridges have been proposed and in 1880 work started on experimental tunnels in Folkstone that were dug by hand and an early tunnel boring machine.

The extent of this work from 1880 and 1881 is shown on OpenStreetMap[0].

[0] https://www.openstreetmap.org/#map=16/51.10884/1.29304

Not mentioned is what to do with the smoke from the locomotive. I expect all the passengers would asphyxiate before they emerged from the other end.

They have another article about a more conventional tunnel idea that addresses that issue. They were well aware of the issue. The only way to make this work at that time would have been something like Brunel's atmospheric railway. That was plagued by issues when in the open, goodness knows what it would have been like to run underground for such a long distance.

https://www.theengineer.co.uk/content/in-depth/this-week-in-...

The big problem with atmospheric railways was sealing the slot in the tube where the piston inside the tube connects to the load. Early atmospheric railways used oiled leather, beeswax, and tallow. Those were not really good enough materials for the job.

There are solutions for this today. They're widely used in rodless pneumatic cylinders.[1] The seal is flexible metal strip to metal, forced closed by the interior pressure of the cylinder. In the 1980s, there was a brief revival of the technology by Aeromovel, which built a few theme park and airport systems. None seem to be still running.

[1] https://tameson.com/pages/rodless-cylinder

In the original (1861) article (big red link halfway down that page), Figure 2 (the tower reaching above the surface) is described primarily as a ventilator to draw away “smoke and foul air”. He had thought about it.

Atmospheric/pneumatic railways were still a popular idea in the mid 19th century. The Dalkey and Paris – St Germain atmospheric railways had each had over a decade of service before closure in the 20 years before Chalmers’ patent. They obviously had their own, considerable issues, but would have reduced the ventilation requirement.

We simply run the trains backwards, emitting exhaust behind us!

(ofc the trouble is how to handle the next train coming in 15 minutes)

OTOH there are such a thing as 'fireless locomotives' which just load up on steam pressure from a stationary boiler and then operate for some miles without need for fuel or any exhaust more noxious than water vapor. But this scheme didn't come for some decades after 1861. I wonder if a cable car would have been feasible.

> I wonder if a cable car would have been feasible.

I would think no reasonably usable cable of that total length would work. But what if you could break it up into segments, with a car releasing the cable of one segment and coasting to grasp the cable of the next segment, and some other system (possibly massively thick cables, possibly some mechanism) underlying it and supplying power to the smaller loops.

That's how SF's cable cars work, where lines cross or there are switches.

What's its max-length run for power transmission ? (It can't be anything close to the English Channel. Can it?)

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