What was the singlemost damaging invention that hurt the railroads?

[Overmod]

Coal gas is not necessarily the same thing as "illuminating gas" which is what I remember being used for the Lenoir motor (and for the early hot-bulb Otto experiments before it was commonly understood that liquid fuels would gasify and carburete just fine!) I always have assumed that coal gas is the gaseous fraction of what distills off when coking coal. Some of this is CO, of course, but I'd expect more of the practical constituents to be hydrocarbons...

I would strongly opine that methane, rather than CO, would be the fuel gas of choice for experimental IC motors using gas fuel, for heat-content and safety reasons just at the start. Although a 'definitive' answer would require knowing just what kind of gas the local lighting authority circa 1860 or so would have been using... and that might be an interesting project for someone to research.

With respect to Diesel, coal dust is what I said, and coal dust is what I meant. Pulverized coal (of the kind now used in boiler firing) is much too slow-burning, completely outside of problems with ashing, handling, erosion, "injection", etc. (Note that pulverized coal wasn't used extensively even in boilers for decades after Diesel's original efforts!)

Remember that the point of compression ignition is to remove any need for a point source of ignition -- be that a spark, glow plug, hot chamber or whatever. And in the late 1800s, one reason to build a much bigger, much heavier, much more precisely-machined engine would be to use a fuel that had some advantage over liquid or gas fuels. High-carbon solids have the heat-content advantage, and compression ignition at least promises to give reasonable percentage of heat release from "slow" combustion and high transition temps. The question then turns to economics: What's a good, cheap engine fuel with high carbon *that has low cost, and preferably is viewed as waste?*

Can anyone say "slack"...

When you hear someone talking about Diesels and "pulverized coal" -- think very, very, very, very finely "pulverized" coal...

I don't remember where the primary sources for the gunpowder engine are now, but they're fairly extensive, and date back IIRC all the way to the 14th Century. Reasoning was that you had a piston (read "cannonball") in a cylinder (read "gun barrel") and you wanted to put high force on that piston via burning something.

There are sketches of engines that use mechanical linkage to recover the force from the "projectile" that date back fairly early in the Renaissance period. Interestingly enough, the pistons are often spherical, with "wadding" serving the purpose of piston rings and 'finish machining', and the tops of the cylinders are made similar to light gun barrels, complete with touchhole, pan, etc. for ignition. I had some fun a few years back, at Columbia, determining how small and practical you could get a gunpowder engine to be using only contemporary technology -- some of the results look markedly peculiar to eyes that have become accustomed to carbureted-liquid-fuel practice!

I believe Denis Papin -- the real inventor of the high-pressure steam engine -- first looked at gunpowder engines, and extrapolated from them to get to the idea of HP steam in the first place. Gunpowder is, in fact, a fuel rather than an explosive, albeit one with very high released energy per gram; the comparatively small feed rate can compensate for the difficulty in feeding a solid or slurried fuel and then touching it off appropriately. It's a long, and seemingly less efficient, way down and away from this to consider critical-mixture or near-critical-mixture combinations of gas and carbureted liquids, solely because they're easier to form and ignite... and in a sense this development required quite a bit of parallel mechanical evolution, both in enabling technology and in perceived need.

[Junctionfan]

Greed-lets face it, alot of the times it is easier and safer to use rail; but is it cheaper than say trucks.

Impatients-it is alot quicker to use truck, car and airplanes than the railways

Politicians-those without vision are the ones who advocate the widening and addition construction of highways rather than spending the same money on rail investment of freight and Amtrak as well as the commuter trains.