introduced . At the start of the 19th century, mechanically powered rail transport had started
to develop, initially by modification and transfer onto wheels of stationary steam engines, which had by
that time become commonplace. Engine design was initially derived from that of stationary steam engines,
with the driving cylinders placed inside the boiler . However, over time, the designs evolved
to satisfy more completely the requirements of a railway engine. Over a similar time
period, passenger vehicle design also evolved, having initially been based almost entirely on stagecoach
design .