Just a piece of trivia for people that are fascinated by Trivia - all
rail carriages were built on a scale of 4 feet eight and half inches wheel gauge and still are.
This was because the people who made the carriages
for the railway were the same ones that made the coaches that travelled on
the roads - and that was the gauge all their tools were designed for.
There was no variation in this scale, you see all the coachbuilders had
developed tools at that gauge because they had to build coaches that would
run on the terrible European roads. These roads up until the beginning of the nineteenth century
were really dirt and mud with little or not surface so they were badly rutted. In a never ending circle all the ruts
were 4 feet eight and a half inches apart, because all coaches were built on
that scale. Carriages were made to that specication because if they didn't fit the ruts in the road they might become
damaged.
That gauge was first developed because the Romans who built the first major roads (and also created the first
major ruts. All roman chariots were built,
you guessed it, at 4 feet eight and half inches wide. And why was that? Because
that was the ideal distance to cover the two horses rears that drew their
chariots. So four feet eight and half inches is basically two horse ass
lengths.
This has been taken from This great web site - so
visit it to find out more about early steam engines
"Every steam engine needs a boiler to make steam from water. In order to generate steam fast enough to supply the engine, most boilers have tubes, either fire tubes or water tubes. These provide a large area of heating surface.
Early boilers and engines had to change about 30 pounds of water to steam every hour to supply one horsepower.
Modern types do better, altough efficiency varies widely according to type.
Fuel consumption can be reduced by preheating water, and air for the fire, with heat from exhaust steam.
Considerable advantage is obtained from superheat. Since increased temperature is needed to produce steam when the overlying pressure is high, early boilers could barely keep high-pressure steam saturated, that is, free from condensed water vapor, as it expanded and cooled while working trought the engine. By passing steam trought tubes surrounded by fire, it can be superheated several hundred degrees. Then its expansion while working the engine will not cause condensation ad loss of power.
Since most water contains minerals which form scale in or around boiler tubes, a water purifier may be needed.
A boiler alsoneeds an "injector" of some kind to force water in agianst back pressure from steam.
Finally every boiler need a "water gauge", to warn when water falls below a safe level, and a "safety valve". This usually has a spring which holds a valve closed tightly against normal steam pressure.
If pressure rise unduly, it force the valve open, releasing steam and relieving the excess pressure.
Modern boilers and engines use steam pressures of hundreds, of ever thousands, of pounds to the square inch.
Railroad locomotives and low-speed ship engines commonly use pressures from 250 pounds upward.
Large turbines, suche as those in electric-power generating stations, use pressures of from 1,400 to 2,000 pounds or more."